Resumo em Inglês:GABA (γ-aminobutyric acid) is a four carbon non-protein amino acid that is widely distributed in plants, animals and microorganisms. As a metabolic product of plants and microorganisms produced by the decarboxylation of glutamic acid, GABA functions as an inhibitory neurotransmitter in the brain that directly affects the personality and the stress management. A wide range of traditional foods produced by microbial fermentation contain GABA, in which GABA is safe and eco-friendly, and also has the possibility of providing new health-benefited products enriched with GABA. Synthesis of GABA is catalyzed by glutamate decarboxylase, therefore, the optimal fermentation condition is mainly based on the biochemical properties of the enzyme. Major GABA producing microorganisms are lactic acid bacteria (LAB), which make food spoilage pathogens unable to grow and act as probiotics in the gastrointestinal tract. The major factors affecting the production of GABA by microbial fermentation are temperature, pH, fermentation time and different media additives, therefore, these factors are summarized to provide the most up-dated information for effective GABA synthesis. There has been a huge accumulation of knowledge on GABA application for human health accompanying with a demand on natural GABA supply. Only the GABA production by microorganisms can fulfill the demand with GABA-enriched health beneficial foods.
Resumo em Inglês:The importance and protection of mangrove ecosystems has been recognized in Brazilian Federal law since 1965. Being protected in law, however, has not always guaranteed their protection in practice. Mangroves are found in coastal and estuarine locations, which are prime real estate for the growth of cities, ports and other economic activities important for Brazilian development. In this mini-review we introduce what mangroves are and why they are so important. We give a brief overview of the microbial diversity found in mangrove sediments and then focus on diversity studies from Brazilian mangroves. We highlight the breadth and depth of knowledge about mangrove microbial communities gained from studying Brazilian mangroves. We report on the exciting findings of molecular microbial ecology methods that have been very successfully applied to study bacterial communities. We note that there have been fewer studies that focus on fungal communities and that fungal diversity studies deserve more attention. The review ends with a look at how a combination of new molecular biology methods and isolation studies are being developed to monitor and conserve mangrove ecosystems and their associated microbial communities. These recent studies are having a global impact and we hope they will help to protect and re-establish mangrove ecosystems.
Resumo em Inglês:Clove essential oil, used as an antiseptic in oral infections, inhibits Gram-negative and Gram-positive bacteria as well as yeast. The influence of clove essential oil concentration, temperature and organic matter, in the antimicrobial activity of clove essential oil, was studied in this paper, through the determination of bacterial death kinetics. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were the microorganisms selected for a biological test. To determine the temperature effect, they were assayed at 21° and 37° C. The concentration coefficient was determined with 0.4%, and 0.2% of essential oil. The influence of the presence of organic matter was determined with 0.4% of essential oil. The results obtained demonstrated that Escherichia coli were more sensitive even though the essential oil exerted a satisfactory action in three cases. In the three microbial species, 0.4% of essential oil at 21º C have reduced the bacterial population in 5 logarithmic orders. Organic matter reduces the antibacterial activity even though the bactericide efficacy was not lost. Clove essential oil can be considered as a potential antimicrobial agent for external use
Resumo em Inglês:The adhesion of the solids presents in food can difficult the process of surface cleaning and promotes the bacterial adhesion process and can trigger health problems. In our study, we used UHT whole milk, chocolate based milk and infant formula to evaluate the adhesion of Enterobacter sakazakii on stainless steel coupons, and we determine the work of adhesion by measuring the contact angle as well as measured the interfacial tension of the samples. Inaddition we evaluated the hydrophobicity of stainless steel after pre-conditioning with milk samples mentioned. E. sakazakii was able to adhere to stainless steel in large numbers in the presence of dairy products. The chocolate based milk obtained the lower contact angle with stainless steel surface, higher interfacial tension and consequently higher adhesion work. It was verified a tendency of decreasing the interfacial tension as a function of the increasing of protein content. The pre-conditioning of the stainless steel coupons with milk samples changed the hydrophobic characteristics of the surfaces and became them hydrophilic. Therefore, variations in the composition of the milk products affect parameters important that can influence the procedure of hygiene in surface used in food industry.
Resumo em Inglês:Brucellosis is an endemic zoonosis in Syria, affecting large numbers of animals and there are an increasing number of cases in humans. The aim of this study is to investigate the in vitro efficacy of various traditional and new antibiotics against89 Brucella isolates (isolated from domestic animals) collected from different Syrian regions. Minimum inhibitory concentrations (MICs) of seventeen antibiotics were determined. Ciprofloxacin and ofloxacin were the most effective antibiotics, whereas sparfloxacin, levofloxacin, doxycycline and tetracycline had a moderate activity. In contrast, moxifloxacin and rifampicin had a low activity, while streptomycin, spiramycin and cephalosporines were ineffective. As a result, we come to the conclusion that a combination between one effective quinolone and doxycycline has a good efficacy against Brucella. Further in vivo studies are necessary to support this suggestion.
Resumo em Inglês:The purpose of this study was to identify the genes coding for resistance to ceftazidime and imipenem and describe the molecular epidemiology of A. baumannii strains isolated from a clinical center in Colombia. Twenty isolates of imipenem-resistant A. baumannii from an equal number of patients with nosocomial infections were obtained. Primers were used to amplify genes bla IMP, bla VIM, bla OXA-23, bla OXA-24, bla OXA-58, bla OXA-51 and bla ADC-7. To detect insertion sequences ISAba1/bla OXA-23, ISAba1/bla OXA-51 and ISAba1/bla ADC-7, mapping by PCR using combinations of reverse primers ISAba1 and reverse primers of bla OXA-23, bla OXA-51 and bla ADC-7 were used. The amplification products were purified and cloned into PCR 2.1-TOPO vector and transformed into chemically competent Escherichia coli TOP10. These amplicons were then sequenced. PFGE was performed on DNA of A. baumannii isolates digested with ApaI. Results. The DNA profiles obtained included 9 clusters with, four 2-7 isolates per profile, and 5 single-isolate profiles. Of the 20 isolates resistant to imipenem, 15 carried bla OXA-23 gene, 4 contained ISAba1 upstream of bla OXA-51 gene, and 6 contained ISAba1 upstream of bla OXA-23 gene. Eighteen of these isolates carried the bla ADC-7 gene, with 9 of the isolates having ISAba1 located upstream of this gene. This is the first report of the ISAba1 /ADC-7 associated with OXAs genes in A. baumannii isolates from Colombia.
Resumo em Inglês:Two-day-old specific pathogen-free (SPF) chickens were divided into two groups. Group I was inoculated orally with fowl adenovirus VIII (FAV-VIII). Group II served as a negative control. Chickens were investigated at various days post-inoculation (dpi) by flow cytometric analysis for changes in T lymphocyte subpopulations in immune system and blood. In the thymus, CD3+ T lymphocytes were increased at 25 dpi, with significant increases in the FAV infected noted at 1, 12, 20dpi (p<0.05). This was accompanied by a corresponding increase of CD4+ and CD8+ T lymphocytes. In the spleen, CD3+ and CD4+ T lymphocytes were increased significantly at 30 dpi (p<0.01) whereas CD8+ and TCR γ δ+ T lymphocytes were decreased at 1 (p<0.05), 30 dpi (p<0.01). An increase of CD3+, CD4+ and CD8+ T lymphocytes was noticed in peripheral blood, and accompanied by a decrease of TCR γ δ+ T lymphocytes. These results demonstrated that infection with FAV-VIII causes significant fluctuations in T lymphocyte subpopulations in thymus, blood and spleen. It can be concluded that an infection with FAV-VIII has profound effects on the immune system, especially on cell mediated immune competency.
Resumo em Inglês:The article presents a comparison between microbiological and high performance liquid chromatographic (HPLC) assays for quantification of moxifloxacin in tablets, ophthalmic solutions and human plasma. The microbiological method employed a cylinder-plate agar diffusion assay using a strain of Esherichia coli ATCC 25922 as the test organism and phosphate buffer (pH8) as the diluent. The calibration curves were linear (R²> 0.98) over a concentration range of 0.125 to 16 µgml-1. The within day and between days precisions were < 4.47% and < 6.39% respectively. Recovery values were between 89.4 and 110.2%. The HPLC assay used Hypersil® BDS C18 reversed phase column (250×4.6 mm, 5µm) with a mobile phase comprising 20 mM ammonium dihydrogen orthophosphate (pH3) and acetonitrile (75:25) and flowing at 1.5 ml/min. The detection was at 295nm. The calibration curves were linear (R²> 0.999) over the range of 0.125 to 16 µg ml-1. The within day and between days precisions were < 4.07% and < 5.09% respectively. Recovery values were between 97.7 and 107.6%. Similar potencies were obtained after the analysis of moxifloxacin tablets and ophthalmic solutions by both methods. Also pharmacokinetic parameters were calculated after the analysis of plasma samples of six male healthhy volunteers by both validated methods.
Resumo em Inglês:Ethanol extracts from six selected species from the Cerrado of the Central-Western region of Brazil, which are used in traditional medicine for the treatment of infectious diseases and other medical conditions, namely Erythroxylum suberosum St. Hil. (Erythroxylaceae), Hyptis crenata Pohl. ex Benth. (Lamiaceae), Roupala brasiliensis Klotz. (Proteaceae), Simarouba versicolor St. Hil. (Simaroubaceae), Guazuma ulmifolia Lam. (Sterculiaceae) and Protium heptaphyllum (Aubl.) March. (Burseraceae), as well as fractions resulting from partition of these crude extracts, were screened in vitro for their antifungal and antibacterial properties. The antimicrobial activities were assessed by the broth microdilution assay against six control fungal strains, Candida albicans, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis and Cryptococcus neoformans, and five control Gram-positive and negative bacterial strains, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. Toxicity of the extracts and fractions against Artemia salina was also evaluated in this work. All plants investigated showed antimicrobial properties against at least one microorganism and two species were also significantly toxic to brine shrimp larvae. The results tend to support the traditional use of these plants for the treatment of respiratory and gastrointestinal disorders and/or skin diseases, opening the possibility of finding new antimicrobial agents from these natural sources.Among the species investigated, Hyptis crenata, Erythroxylum suberosum and Roupala brasiliensis were considered the most promising candidates for developing of future bioactivity-guided phytochemical investigations.
Resumo em Inglês:Mutations in the quinolone resistance-determining regions (QRDR) in chromosomal gyrA and parC genes and fluoroquinolone susceptibility profiles were investigated in quinolone-resistant Enterobacteriaceae isolated from community and hospitalized patientsin the Brazilian Southeast region. A total of 112 nalidixic acid-resistant enterobacterial isolates collected from 2000 to 2005 were investigated for mutations in the topoisomerases genes gyrA and parC by amplifying and sequencing the QRDR regions. Susceptibility to fluoroquinolones was tested by the agar dilution method. Amongst the 112 enterobacterial isolates, 81 (72.3%) were resistant to ciprofloxacin and 5 (4.5%) showed reduced susceptibility. Twenty-six (23.2%) were susceptible to ciprofloxacin. Several alterations were detected in gyrA and parC genes. Escherichia coli isolates (47.7%) showed double mutations in the gyrA gene and a single one in the parC gene. Two unusual aminoacid substitutions are reported, an Asp87-Asn in a Citrobacter freundii isolate with reduced susceptibility to fluoroquinolones and a Glu84-Ala in one E. coli isolate.Only a parC gene mutation was found in fluoroquinolone-susceptible Enterobacter aerogenes. None of the isolates susceptible to ciprofloxacin presented mutations in topoisomerase genes. This comprehensive analysis of QRDRs in gyrA and parC genes, covering commonly isolated Enterobacteriaceae in Brazil is the largest reported up to now.
Resumo em Inglês:The "In vitro" antifungal activity of ozonized sunflower oil (Bioperoxoil®) was tested on 101 samples of yeasts originating from onychomycosis using the disk diffusion method. The oil was efficacious against several clinical fungal strains: Candida parapsilosis, Candida albicans, Trichosporonasahii, Candida tropicalis and Candida guilliermondii.
Resumo em Inglês:The availability of a useful tool for simple and timely detection of the most important virulent varieties of Escherichia coli is indispensable. To this end, bacterial DNA pools which had previously been categorized were obtained from isolated colonies as well as selected in terms of utilized phenotype; the pools were assessed by two PCR Multiplex for the detection of virulent E. coli eaeA, bfpA, stx1, stx2, ipaH, ST, LT, and aatA genes, with the 16S gene used as DNA control. The system was validated with 66 fecal samples and 44 wastewater samples. At least one positive isolate was detected by a virulent gene among the 20 that were screened. The analysis of fecal samples from children younger than 6 years of age detected frequencies of 25% LT positive strains, 8.3% eae, 8.3% bfpA, 16.7% ipaH, as well as 12.5 % aatA and ST. On the other hand, wastewater samples revealed frequencies of 25.7% eaeA positive, 30.3% stx1, 15.1% LT and 19.7% aatA. This study is an initial step toward carrying out epidemiological field research that will reveal the presence of these bacterial varieties.
Resumo em Inglês:To review the bacteriological features of infectious spondylodiscitis and provide recommendations for the initial therapy which remains empirical in our context. Retrospective study including patients diagnosed with spondylodiscitis over a period of 4 years (2006-2009) at the Rabat Military Teaching Hospital. During the study period, we analysed 30 cases: the mean age was 49.9 years and 21 cases (70%) were male. The patients were predominantly hospitalized in neurosurgery department (15/30) followed by rheumatology department (10/30). The site of infection was lumbar in 21 cases (21/30), dorsal in 7 cases (7/30). 26 cultures were positive of which 19 (19/26) were monomicrobial. Tuberculosis (TB) was implicated in 10 cases (10/30) including 4 cases in association with common organisms (Propionibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, Corynebacterium species). Brucella melitensis was isolated in 1 case. Infections caused by pyogenic bacteria were isolated in 15 cases of which 12 (12/15) revealed simple organisms including Gram-positive cocci in 9 cases (9/12) with 3 cases of S. aureus and Gram-negative bacilli in 3 cases (3/12) with 2 cases of P. aeruginosa. Blood cultures carried out for 16 patients were positive in 7 cases. The anatomopathologic exams carried out for 20 patients found in 6 cases epithelioid granulomata and giants cells with caseous necrosis in total concordance with TB culture. TB is the most frequent cause of spondylodiscitis in Morocco. Our study found the same frequency for non-specific and specific germs. Empirical treatment must take into account S. aureus and M. tuberculosis.
Resumo em Inglês:There is not much information available regarding the prevalence of the genotypes of Helicobacter pylori isolates in Turkey, particularly in eastern Turkey. The aims of this study were to detect the prevalence of different genotypes of H. pylori in Turkish patients with gastrointestinal complaints and to determine the relationship of these genotypes with clinical outcome and sex. One hundred forty H. pylori isolates were examined for the presence of its genotypes by the PCR. We found that the prevalence of vacA s1, vacA s2, cagA, cagE, iceA1, iceA2 and babA2 genes were 88.6%, 11.4%, 71.4%, 35.7%, 41.4%, 58.6%, and 62.1%, respectively. The most predominant vacA subtype was s1a (81.4%). The most vacA allelic combination detected were vacA s1m1 (65.2%)and s1m2 (53.9%) in patients with peptic ulcer and gastritis, respectively. The only vacA s1 isolate was significantly associated with gastritis and peptic ulcer (p<0.05). The vacA s1a, ml, slml and babA2 genes were significantly associated with peptic ulcer (p<0.05), whereas m2 gene was significantly associated with only gastritis (p<0.05). The difference between sex and genotypes was statistically significant among the cagA, vacA s1, iceA2 and babA2 genes. This study reported for the first time the prevalence of H. pylori genotypes in patients with gastrointestinal complaints in eastern Turkey. Further studies are needed to understand epidemiological importance of the genotypes of H. pylori isolates in this region and the association between the virulence genes and clinical outcome in different regions.
Resumo em Inglês:A total of 112 soil samples were taken from differents areas of district D.I.Khan and Kohat (KPK) Pakistan and screened for production of antibiotics against the Micrococcus luteus and Staphylococcus aureus. Widest zone of inhibition (18mm) was produced by microorganism isolated from saline soil. The strain was later identified as Bacillus GU057 by standard biochemical assays. Maximum activity (18mm inhibition zone) was observed against Staphylococcus aureus after 48 hours of incubation at pH 8 and 4% concentration of glucose. The antibiotic was identified by autobiography as bacitracin. The Bacillus strain GU057 was confirmed as good peptide antibiotic producer and can effectively be indulged as biocontrol agent.
Resumo em Inglês:Piedra, is an asymptomatic fungal infection of the hair shaft, resulting in the formation of nodules of different hardness on the infected hair. The infection also known as Trichomycosis nodularis is a superficial fungal infection arising from the pathogen being restricted to the stratum corneum with little or no tissue reaction. The nodules are a concretion of hyphae and fruiting bodies of the fungus. Two varieties of Piedra may be seen, Black Piedra and White Piedra. The fungus Trichosporon ovoides is involved in the occurrence of both types of Piedras. The purpose of this study was to examine the effectiveness of selected essential oils for the control of growth of the fungus and to determine whether the antifungal effect was due to the major compounds of the oils. Two screening methods viz. Agar well diffusion assay and Minimum Inhibitory Concentration were adopted for the study. MIC and MFC were determined by tube dilution method. Essential oils from Eucalyptus, Ocimum basilicum, Mentha piperita, Cymbopogon flexuosus, Cymbopogon winterians, Trachyspermum ammi, Zingiber officinalis, Citrus limon, Cinnamomon zeylanicum, Salvia sclarea, Citrus aurantifolia, Melaleuca alternifolia, Citrus aurantium, Citrus bergamia, Pogostemon pathchouli, Cedrus atlantica, Jasminum officinale, Juniperus communis, Abelmoschus moschatus, Cyperus scariosus, Palargonium graveolens, Boswellia carterii, Rosa damascene, Veteveria zizanoides and Commiphora myrrha were evaluated. The essential oils of Cymbopogon winterians, Mentha piperita, Cinnamomum zeylanicum, Melaleuca alternifolia and Eucalyptus globulus were proved to be most effective against the fungus Trichosporon ovoides.
Resumo em Inglês:By using agar well diffusion assay, antifungal activity of aqueous extract prepared from Egyptian garlic (Allium sativum L.) was evaluated in vitro against two strains of Aspergillus flavus (OC1 and OC10) causing human ocular infection. The recorded minimum inhibitory concentration (MIC) for growth inhibition of both strains was 3.60 mg/ml. Aqueous garlic extract (AGE) was used in successive in vivo tests as an attempt to cure rabbit's fungal keratitis caused by A. flavus OC1. Findings showed that diluted preparation of AGE was effective topical antifungal agent and succeeded to cure severe A. flavus keratitis in a time course less than 10 days without any observable side effects. Microscopic examination showed that AGE induced deleterious cyto-morphological aberrations inA. flavus target cells. AGE applied to Czapek's broth via contact method was more effective on growth, spores and aflatoxin B1 production than AGE applied to the same broth at the same concentration via fumigation method.
Resumo em Inglês:Vibrio harveyi is considered as a causative agent of the systemic disease, vibriosis, which occurs in many biological fields. The effects of temperatures (12.9-27.1 ºC) and water activity (NaCl% 0.6%-3.4%) on V. harveyi were investigated. The behavior and growth characteristics of V. harveyi was studied and modeled. Growth curves were fitted by using Gompertz and Baranyi models, and the Baranyi model showed a better fittness. Then, the maximum growth rates (µmax) and lag phase durations (LPD, λ) obtained from both Gompertz and Baranyi model were modeled as a combination function of temperature and water activity using the response surface and Arrhenius-Davey models for secondary model. The value of r², MSE, bias and accuracy factor suggest Baranyi model has better fitness than Gompertz model. Furthermore, validation of the developed models with independent data from ComBase also shown better interrelationship between observed and predicted growth parameter when using Baranyi model.
Resumo em Inglês:As lactobacilli possess an antagonistic growth property, these bacteria may be beneficial as bioprotective agents for infection control. However, whether the antagonistic growth effects are attributed to the lactobacilli themselves or their fermentative broth remains unclear. The antagonistic growth effects of Lactobacillus salivarius and Lactobacillus fermentum as well as their fermentative broth were thus tested using both disc agar diffusion test and broth dilution method, and their effects on periodontal pathogens, including Streptococcus mutans, Streptococcus sanguis, and Porphyromonas gingivalisin vitro at different concentrations and for different time periods were also compared. Both Lactobacillus salivarius and Lactobacillus fermentum and their concentrated fermentative broth were shown to inhibit significantly the growth of Streptococcus mutans, Streptococcus sanguis, and Porphyromonas gingivalis, althoughdifferent inhibitory effects were observed for different pathogens. The higher the counts of lactobacilli and the higher the folds of concentrated fermentative broth, the stronger the inhibitory effects are observed. The inhibitory effect is demonstrated to be dose-dependent. Moreover, for the lactobacilli themselves, Lactobacillus fermentum showed stronger inhibitory effects than Lactobacillus salivarius. However, the fermentative broth of Lactobacillus fermentum showed weaker inhibitory effects than that of Lactobacillus salivarius. These data suggested that lactobacilli and their fermentative broth exhibit antagonistic growth activity, and consumption of probiotics or their broth containing lactobacilli may benefit oral health.
Resumo em Inglês:In the present study the effects on shelf life and sensory acceptance of gamma-irradiated refrigerated poultry breast fillets subjected to modified atmosphere packaging (80% CO2/20% N2 or vacuum) were investigated. After irradiation with 2 kGy, sensory acceptance tests and monitoring of bacterial growth were performed in order to determine the sanitary quality of the samples. It has been found that irradiation, used in combination with modified atmosphere packaging, can double the shelf life of refrigerated poultry breast fillets by reducing the populations of aerobic mesophilic and psychrotrophic bacteria, enterobacteria, coliforms, Listeria spp. and Aeromonas spp., without significantly modifying its color or its overall appearance, the lactic acid bacteria being the most resistant to exposure to radiation and carbon dioxide.
Resumo em Inglês:The present paper evaluated the microbiology of salmon by quantifying mesophilic heterotrophic microorganisms, total and thermotolerant coliforms, and the presence of Vibrio parahaemolyticus, Staphylococcus aureus, Salmonella sp., Escherichia coli and Aeromonas sp. in the meat. This study can provide technical support for the suggestion of a new regulation of a Brazilian legislation through specific microbiological standards concerning the consumption of raw fish. A number of 31 (16 cooled and 15 frozen) samples of salmon were collected in the retail market network of a few cities in the State of São Paulo, Brazil. Results presented populations of mesophilic heterotrophic microorganisms ranging from 1.0 x 10 and 3.9 x 10(6) CFU/g, total and thermotolerant coliforms in 32.25% and 19.35% of the samples, respectively, and Aeromonas sp. in 41.95% of the samples with a populational variation ranging from 2.0 x 10² to 8.0 x 10³ CFU/g. Staphylococcus aureus was found in one sample whereas Vibrio parahaemolyticus, Salmonella sp. and Escherichia coli were not found. These results demonstrated the presence of potencially pathogenic microorganisms in fresh fish consumed in Brazil, highlighting the necessity of control measures to avoid public health problems related to the consumption of raw fish.
Resumo em Inglês:The behaviour of enterotoxin-producing Bacillus cereus in meat was investigated by inoculating spore suspensions of five cultures into meat substrate (pH 5.8) and incubating at 10ºC and 30ºC. The bacterial populations were evaluated after different times by plate counts in nutrient agar. All the cultures presented growth at 30ºC with the generation time varying from 28.8 to 36.0 minutes. Three cultures also presented growth at 10ºC with generation times between 10.16 and 28.38 h. Considering the results, it was concluded that meat kept at abusive temperatures would be subject to development of this microorganism.
Resumo em Inglês:The purpose of this study was to investigate the effect of different levels of Pseudomonas fluorescens (10² and 10(6)log10 cfu/ml)and Lactobacillus plantarum (10² and 10(4)log10 cfu/ml)on the growth of Escherichia coli O157:H7 on beef loins. Beef loins inoculated with E. coli O157:H7 and P. fluorescens were aerobically stored for 7 days at 4 ºC, while those inoculated with E. coli O157:H7 and L. plantarum were vacuum packaged and stored for 8 weeks at 4 ºC. Aerobic Plate Counts (APC), E. coli O157:H7 and either P. fluorescens or L. plantarum counts were determined at different storage intervals. For the aerobically packaged beef loins, E. coli O157:H7 was detected throughout the 7 day storage period regardless of the P. fluorescens level in the inoculum. For the vacuum packaged beef loins, similar inoculum levels of E. coli O157:H7 and L. plantarum allowed E. coli O157:H7 to survive until week 5 of storage, while a higher inoculum level of L. plantarum inhibited E. coli O157:H7 from week 3. Once fresh beef has been contaminated with E. coli O157:H7, the level of P. fluorescens in the background flora does not inhibit its survival and growth. However, under vacuum storage, the application of L. plantarum as a biopreservative inhibits the survival of E. coli O157:H7 on beef. The higher the level of L. plantarum in the system, the earlier the onset of the inhibition. Farmers and abattoirs have to strengthen preventive strategies to eliminate contamination of beef carcasses with E. coli O157:H7.
Resumo em Inglês:The effectiveness of free and nanovesicle-encapsulated nisin to control Listeria monocytogenes in Minas Frescal cheese was investigated. Commercial nisin was encapsulated into liposomes of partially purified soy lecithin. Free (0.1 mg/mL and 0.25 mg/mL) and nanovesicle-encapsulated nisin (0.25 mg/mL) were applied onto the surface of cheese samples, and L. monocytogenes was inoculated before incubation at 6-8°C for 28 days. A bactericidal effect was observed with 0.25 mg/mL free nisin; a bacteriostatic effect was observed for liposome-encapsulated nisin and 0.1 mg/mL free nisin. Free nisin was more efficient than nisin-loaded liposomes in controlling L. monocytogenes. Possible reasons for this behavior, and also the significance of nisin to soft cheeses are discussed. Nisin acted as a suitable barrier within hurdle technology, potentially extending the shelf-life and safety of fresh cheeses.
Resumo em Inglês:Antimicrobial active packaging delays or inhibits microorganism growth in packed products, and it can be used in a variety of food systems. The objective of the present research was to develop packaging incorporated with natural antimicrobial agents (active film). The effects of the active film on the spoilage, pathogenic microorganism counts, pH and color of the refrigerated chicken breast cuts were analyzed. Cellulose acetate-based active films incorporating two concentrations (20% and 50%, v/w) of rosemary (Rosmarinus officinalis L.) essential oil were manufactured and placed in contact with the chicken breast cuts for six days. An analysis of variance and mean comparison tests (Tukey's test, p<0.05) were performed on the results. The films that contained 20% essential oil and were intercalated with chicken breast samples did not demonstrate significant effects on the control of psychrotrophic or total coliform microorganisms during the storage period; however, the films incorporated with 50% essential oil demonstrated efficacy toward the control of coliforms during the storage of the samples (6 days, 2 ± 2ºC). The pH was related to the psychrotrophic microorganism count and was not influenced by the treatment. The color was not influenced by the time of storage or the treatment. The results demonstrate that active films incorporating 50% rosemary essential oil are effective at controlling certain microorganisms in chicken breast cuts.
Resumo em Inglês:The media claims for the consumption of natural resource-based food have gradually increased in both developing and developed countries. The interest in the safety of these products is partially due to the possible presence of toxigenic fungi acting as mycotoxin producers, such as aflatoxins produced during the secondary metabolism of Aspergillus flavus, A. parasiticus and A. nomius. Aflatoxins, mainly aflatoxin B1, are directly associated with liver cancer in human beings. This paper is aimed at evaluating the presence of aflatoxin B1 in a few vegetable drugs, dried plant extracts and industrialized products traded in 2010 in the city of Belo Horizonte, State of Minas Gerais, Brazil. The method used for the quantification of aflatoxin B1 was based on extraction through acetone:water (85:15), immunoaffinity column purification followed by separation and detection in high efficiency liquid chromatography. Under the conditions of analysis, the Limits of Detection and Quantification were 0.6 µg kg-1 and 1.0 µg kg-1respectively. The complete sets of analyses were carried out in duplicate. Aflatoxin B1 was noticed in a single sample (< 1.0 µg kg-1). The results revealed low aflatoxin B1contamination in the products under analysis. However, it is required to establish a broad monitoring program in order to obtain additional data and check up on the actual extension of contamination.
Resumo em Inglês:The purpose of this study was to determine the microbiological air quality (psychrotrophic bacteria and airborne fungi) and distribution of fungi in different types of ready-to-eat (RTE) food-storage refrigerators (n=48) at selected retail stores in the city of Edirne, Turkey. Refrigerators were categorized according to the type of RTE food-storage: meat products, vegetables, desserts, or a mix of food types. Microbiological quality of air samples was evaluated by using a Mas-100 Eco Air Sampler. Four refrigerators (all containing meat products, 8.3%) produced air samples with undetectable microorganisms. The highest detected mean value of airborne psychrotrophic bacteria and fungi was 82.3 CFU/m³ and 54.6 CFU/m³, respectively and were found in mixed-food refrigerators. The dominant airborne fungal genera found were Penicillium (29.0%), Aspergillus (12.0%), Mucor (9%), Cladosporium (8%), Botyrtis (7%), and Acremonium (6%). By definition, RTE food does not undergo a final treatment to ensure its safety prior to consumption. Therefore, ensuring a clean storage environment for these foods is important to prevent food-borne disease and other health risks.
Resumo em Inglês:The mycoflora of the environment: wheat conditioning, milling and screening, and filling zone, as well as, raw material -wheat-, intermediate product -grits- and end product -flour- on day 1, and after cleaning improvements -days 45 and 90- were studied in an Argentine wheat mill. Samples were incubated at 28°C for 5-7 days on Malt Extract Agar with chloramphenicol (100 mg L-1) and the results were expressed in colony forming units per cubic meter of air (CFU m-3) or per gram of sample (CFU g-1), respectively. Fungal genera and species were isolated and identified and the potential toxicogenic capacity of the Aspergillus flavus and Fusarium graminearum isolated was studied. Time-Place and Time-Product multifactorial ANOVA were carried out. After cleaning improvements, CFU m-3 of air decreased as a function of time. Cladosporium and Alternaria were abundant in every zone, Aspergillus predominated in the wheat conditioning zone and Penicillium and Eurotium decreased with time. Wheat was more contaminated than grits and flour; Aspergillus, Eurotium and Mucoraceae family were the most abundant. Deoxynivalenol was above the levels allowed in wheat, being acceptable in grits and flour. Aflatoxin and Zearalenone showed acceptable levels. When studied in vitro, 53% of Aspergillus flavus and 100% of Fusarium graminearum isolates, produced Total Aflatoxins, and Deoxynivalenol and Zearalenone, respectively.
Resumo em Inglês:A bacteriocin-like inhibitory substance producing Lactococcus lactis subsp lactis strain, ST1, isolated from goat milk of Iranian origin and with broad spectrum of activity and desirable technical properties was used for evaluating some futures of bacteriocin inhibitory activity. Cell growth and bacteriocin production studies were carried out in MRS medium incubated statically under uncontrolled pH condition. The antibacterial activity presented a primary metabolite pattern and showed a rapid decrease at the stationary phase. Microaerobiosis and capnophily growth conditions resulted in higher bacteriocin production while aerobiosis showed negative effect on both cell growth and bacteriocin production. Bacteriocin production, on the other hand, was favored in MRS broth (pH; 6.5) inoculated with 0.1 ml l-1 fresh culture when incubation was carried out at 30 °C. This indicated that the conditions resulted in higher levels of growth were frequently favoring bacteriocin production by ST1 as well. Decrease in activity, at the stationary growth phase, was much pronounced in favored growth condition. Nutrient depletion, deferent effect of low pH on bacteriocin production and/or protein degradation seemed more responsible for this phenomenon. The study also provided further data on new method for bacteriocin release from the cell wall of producer. It was clearly shown that both heating and ultrasound shock for 5 min at pH 2 could increase bacteriocin activity significantly. The release was more pronounced in the presence of 0.5% Tween80.
Resumo em Inglês:Microbiological analyses of chicken eggs in Recife and Salvador have shown a high occurrence of Salmonella in the egg shells and yolks. Likewise, the occurrence of Salmonella plus coagulase-positive staphylococci in Coalho cheese reached alarming levels. The data revealed a significant risk of infections and intoxications from consuming these foods in the cities.
Resumo em Inglês:The characteristics of an endoglucanase produced by a Trichoderma virens strain T9 newly isolated from a palm-fruit husk dump site, its physiological characteristics and enzyme production were studied. Whole cells of the depolymerizing-enzyme producing T. virens were applied to palm-fruit husk and bird performance characteristics when employed as poultry diet additive were considered. Endoglucanase activity in submerged fermentation was 1.6 nkat. Optimum activity was recorded at pH 6.0 and 55ºC. The enzyme retained 50% residual glucanase activity at 70ºC for 10 minutes. 1.0% Tween-80 and SDS yielded endoglucanase activity 2.15 times higher than the control. Activity wasboosted by 20mM Ca2+ (115.0%); 10mM K+ (106.5%); and was totally inhibited by 1mM Hg2+. The addition of T. virens -fermented palm-fruit husk with other layer feed components on the bird characteristics showed that change in bird weight between the control and test birds were not significantly different (p>0.05) but differed in terms of daily feed ingested (p<0.05). The feed to weight-gain ratio was best with the unmodified palm-fruit husk based diet (8.59). There was no significant difference in the egg weights from modified palm-fruit husk based diet and control (p>0.05). The shell thickness (0.64mm) and yolk content (23.61%) were highest in the microbially-modified husk diet. The alternative to maize based diets proffered by the application of T. virens -modified palm-fruit husk in poultry nutrition in terms of bird weight and feed to weight-gain ratio affords the poultry farmer an economic advantage and allows for a greater utilization of the maize in human diets.
Resumo em Inglês:We have established methodology for the isolation and characterization of a novel endophytic fungus from the inner bark of medicinal plant Nothapodytes foetida, which produced camptothecin in Sabouraud broth (SB) under shake flask conditions. Camptothecin and its related compounds are at present obtained by extraction from intact plants, but fungal endopytes may be an alternative source of production. In present study we have observed the effect of different nutrient combinations and precursors (tryptophan, tryptamine, geraniol, citral, mevalonic acid and leucine) on the accumulation of camptothecin by endophytic fungus Entrophospora infrequens. The precursors were fed either alone or in combinations (tryptophan and geraniol, tryptophan and citral, tryptophan and mevalonic acid, tryptophan and leucine). The highest camptothecin content was observed in the range of 503 ± 25µg/100g dry cell mass in Sabouraud medium. Camptothecin content in the medium was increased by 2.5 folds by the presence of tryptophan and leucine whereas the production with trytophan was also significantly different from other treatments. Furthermore, the effect of fungal camptothecin on the morphology of human cancer cell lines was also studied. The treated cells showed reduction in size, condensation of nucleus and the protoplasmic extensions were reduced. All these characteristics are found in apoptotic cells.
Resumo em Inglês:The lipase produced by a newly isolate Sporidiobolus pararoseus strain has potential catalysis ability for esterification reactions. In order to improve its synthetic activity, this work aimed at optimizing 'synthetic lipase' production by submerged fermentation of a conventional media based on peptone, yeast extract, NaCl and olive oil using experimental design technique. According to the results obtained in the first experimental design (2(4-1)), yeast extract and NaCl concentrations were tested to further optimization by response surface methodology. The maximum 'synthetic lipase' activity obtained was 26.9 U/mL in the optimized media (5.0, 6.8, 7.0 and 1.0% (wt/v) of peptone, yeast extract, NaCl and olive oil, respectively), representing a 6.36-fold increase compared to the initial medium. The time course of 'synthetic lipase' production in the optimized condition was evaluated in terms of synthetic activity, protease activity, biomass and total carbon and the maximum synthetic activity was observed during the stationary phase of growth.
Resumo em Inglês:Bio-ethanol production from cane molasses (diluted to 15 % sugar w/v) was studied using the bacterium, Zymomonas mobilis MTCC 92 entrapped in luffa (Luffa cylindrica L.) sponge discs and Ca-alginate gel beads as the immobilizing matrices. At the end of 96 h fermentation, the final ethanol concentrations were 58.7 ± 0.09 and 59.1 ± 0.08 g/l molasses with luffa and Ca-alginate entrapped Z. mobilis cells, respectively exhibiting 83.25 ± 0.03 and 84.6 ± 0.02 % sugar conversion. There was no statistical significant difference (Fischer's LSD) in sugar utilization (t = 0.254, p <0.801) and ethanol production (t =-0.663, p <0.513) between the two immobilization matrices used. Further, the immobilized cells in both the matrices were physiologically active for three more cycles of operation with less than 15 % decrease in ethanol yield in the 4th cycle, which was due to some leakage of cells. In conclusion, luffa sponge was found to be equally good as Ca-alginate as a carrier material for bacterial (Z. mobilis. cell immobilization for ethanol production. Further, it has added advantages such as it is cheap, non-corrosive and has no environmental hazard.
Resumo em Inglês:The mushroom Pleurotus ostreatus has nutritional and medicinal characteristics that depend on the growth substrate. In nature, this fungus grows on dead wood, but it can be artificially cultivated on agricultural wastes (coffee husks, eucalyptus sawdust, corncobs and sugar cane bagasse). The degradation of agricultural wastes involves some enzyme complexes made up of oxidative (laccase, manganese peroxidase and lignin peroxidase) and hydrolytic enzymes (cellulases, xylanases and tanases). Understanding how these enzymes work will help to improve the productivity of mushroom cultures and decrease the potential pollution that can be caused by inadequate discharge of the agroindustrial residues. The objective of this work was to assess the activity of the lignocellulolytic enzymes produced by two P. ostreatus strains (PLO 2 and PLO 6). These strains were used to inoculate samples of coffee husks, eucalyptus sawdust or eucalyptus bark add with or without 20 % rice bran. Every five days after substrate inoculation, the enzyme activity and soluble protein concentration were evaluated. The maximum activity of oxidative enzymes was observed at day 10 after inoculation, and the activity of the hydrolytic enzymes increased during the entire period of the experiment. The results show that substrate composition and colonization time influenced the activity of the lignocellulolytic enzymes.
Resumo em Inglês:The treatment of tuberculosis has become more difficult with the worldwide spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis. Moreover, the prevalence of human disease caused by atypical mycobacteria has also increased in the past two decades and has further complicated the problem of the treatment of mycobacterial infections. It is therefore urgent to develop new highly active molecules against these bacteria. The present study reports the isolation from a Moroccan soil of a Bacillus strain that exhibits an important antimycobacterial activity. The strain was identified as Brevibacillus laterosporus using DNA sequencing of the 16S ribosomal RNA gene. The antimycobacterial activity was assigned to a substance with a protein nature. This nature was revealed using a liquid-liquid extraction with organic solvents, precipitation with ammonium sulfate and treatment with a protease. This study suggested the identification and the characterization of this active metabolite enabling therapeutic investigations further.
Resumo em Inglês:This study was designed to evaluate selected chemical and microbiological treatments for the conversion of certain local agro-industrial wastes (rice straw, corn stalks, sawdust, sugar beet waste and sugarcane bagasse) to ethanol. The chemical composition of these feedstocks was determined. Conversion of wastes to free sugars by acid hydrolysis varied from one treatment to another. In single-stage dilute acid hydrolysis, increasing acid concentration from 1 % (v/v) to 5 % (v/v) decreased the conversion percentage of almost all treated agro-industrial wastes. Lower conversion percentages for some treatments were obtained when increasing the residence time from 90 to 120min. The two-stage dilute acid hydrolysis by phosphoric acid (1.0 % v/v) followed by sulphuric acid (1.0 % v/v) resulted in the highest conversion percentage (41.3 % w/w) on treated sugar beet waste. This treatment when neutralized, amended with some nutrients and inoculated with baker's yeast, achieved the highest ethanol concentration (1.0 % v/v). Formation of furfural and hydroxymethylfurfural (HMF) were functions of type of acid hydrolysis, acid concentration, residence time and feedstock type. The highest bioconversion of 5 % wastes (37.8 % w/w) was recorded on sugar beet waste by Trichoderma viride EMCC 107. This treatment when followed by baker's yeast fermentation, 0.41 % (v/v) ethanol and 8.2 % (v/w) conversion coefficient were obtained.
Resumo em Inglês:This work is aimed to produce endoglucanase through solid state fermentation in a packed bed bioreactor with the use of the fungus Myceliophtora sp. I-1D3busing a mixture of wheat bran (WB) and sugar cane bagasse (SCB) as culture medium. Preliminary tests were performed in polypropylene plastic bags, controlling the variables temperature (40, 45, and 50ºC), initial moisture content (75, 80, and 85%, w.b.), and weight proportion SCB/WB (1:1, 7:3, and 9:1). The highest enzyme activities in plastic bags were obtained using the substrate proportion of 7:3, 50ºC temperature, and 80% initial moisture content (878 U/grams of dry solid). High activities of filter-paper cellulase and xylanase were also obtained in plastic bags and some results are reported. For the packed bed experiments, the temperature (45 and 50ºC) and the air flow rate (80, 100 and 120L/h) were the controlled variables. Activity of endoglucanase was similar to plastic bag tests. A longitudinal gradient of moisture content, was observed increasing from the bottom to the top of the reactor, even though the longitudinal enzyme activity profile was flat for almost the whole bed. Air flow rate did not affect enzyme activity, while experiments carried out at 50ºC showed higher enzyme activities. The maximum temperature peak observed was at about 6ºC above the process temperature.
Resumo em Inglês:Agro-industrial wastes such as sugarcane bagasse, wheat bran, rice bran, corn cob and wheat straw are cheapest and abundantly available natural carbon sources. The present study was aimed to production of amylase and xylanase simultaneously using agro-industrial waste as the sole carbon source. Seven thermophilic strains of actinomycete were isolated from the mushroom compost. Among of these, strain designated MSC702 having high potential to utilize agro-industrial wastes for the production of amylase and xylanase. Strain MSC702 was identified as novel species of Streptomyces through morphological characterization and 16S rRNA gene sequence. Enzyme production was determined using 1% (w/v) of various agro-industrial waste in production medium containing (g/100mL): K2HPO4(0.1), (NH4)2SO4(0.1), NaCl (0.1), MgSO4(0.1) at pH 7.0 after incubation of 48 h at 50°C. The amylase activity (373.89 IU/mL) and xylanase activity (30.15 IU/mL) was maximum in rice bran. The decreasing order of amylase and xylanase activity in different type of agro-industrial wastes were found rice bran (RB) > corn cob (CC) > wheat bran (WB) > wheat straw (WS) > sugarcane bagasse (SB) and rice bran (RB) > wheat bran (WB) > wheat straw (WS) > sugarcane bagasse (SB) > corn cob (CC), respectively. Mixed effect of different agro-industrial wastes was examined in different ratios. Enzyme yield of amylase and xylanase was ~1.3 and ~2.0 fold higher with RB: WB in 1:2 ratio.
Resumo em Inglês:A mutant designated NC2168, which was selected from wild-type Streptococcus equisimilis CVCC55116by ultraviolet ray combined with60Co-γ ray treatment and does not produce streptolysin, was employed to produce hyaluronic acid (HA). In order to increase the output of HA in a flask, the culture medium and conditions for NC2168 were optimized in this study. The influence of culture medium ingredients including carbon sources, nitrogen sources and metal ions on HA production was evaluated using factional factorial design. The mathematical model, which represented the effect of each medium component and their interaction on the yield of HA, was established by the quadratic rotary combination design and response surface method. The model estimated that, a maximal yield of HA could be obtained when the concentrations of yeast extract, peptone, glucose, and MgSO4 were set at 3 g/100 mL, 2 g/100 mL, 0.5 g/100 mL and 0.15 g/100 mL, respectively. Compared with the values obtained by other runs in the experimental design, the optimized medium resulted in a remarkable increase in the output of HA and the maximum of the predicted HA production was 174.76 mg/L. The model developed was accurate and reliable for predicting the production of HA by NC2168.Cultivation conditions were optimized by an orthogonal experimental design and the optimal conditions were as follows: temperature 33ºC, pH 7.8, agitation speed 200 rpm, medium volume 20 mL.
Resumo em Inglês:The common bean is one of the most important legumes in the human diet, but little is known about the endophytic bacteria associated with the leaves of this plant. The objective of this study was to characterize the culturable endophytic bacteria of common bean (Phaseolus vulgaris. leaves from three different cultivars (Vermelhinho, Talismã, and Ouro Negro) grown under the same field conditions. The density of endophytic populations varied from 4.5 x 10² to 2.8 x 10³ CFU g-1 of fresh weight. Of the 158 total isolates, 36.7% belonged to the Proteobacteria, 32.9% to Firmicutes, 29.7% to Actinobacteria, and 0.6% to Bacteroidetes. The three P. vulgaris cultivars showed class distribution differences among Actinobacteria, Alphaproteobacteria and Bacilli. Based on 16S rDNA sequences, 23 different genera were isolated comprising bacteria commonly associated with soil and plants. The genera Bacillus, Delftia, Methylobacterium, Microbacterium, Paenibacillus, Staphylococcus and Stenotrophomonas were isolated from all three cultivars. To access and compare the community structure, diversity indices were calculated. The isolates from the Talismã cultivar were less diverse than the isolates derived from the other two cultivars. The results of this work indicate that the cultivar of the plant may contribute to the structure of the endophytic community associated with the common bean. This is the first report of endophytic bacteria from the leaves of P. vulgaris cultivars. Future studies will determine the potential application of these isolates in biological control, growth promotion and enzyme production for biotechnology.
Resumo em Inglês:Vegetable oils and their derivatives, like biodiesel, are used extensively throughout the world, thus posing an environmental risk when disposed. Toxicity testing using test organisms shows how these residues affect ecosystems. Toxicity tests using earthworms (Eisenia foetida. are widespread because they are a practical resource for analyzing terrestrial organisms. For phytotoxicological analysis, we used seeds of arugula (Eruca sativa and lettuce (Lactuca sativa. to analyze the germination of seeds in contaminated soil samples. The toxicological experiment was conducted with four different periods of biodegradation in soil: zero days, 60 days, 120 days and 180 days. The studied contaminants were soybean oil (new and used) and biodiesel (B100). An evaluation of the germination of both seeds showed an increased toxicity for all contaminants as the biodegradation occurred, biodiesel being the most toxic among the contaminants. On the other hand, for the tests using earthworms, the biodiesel was the only contaminant that proved to be toxic. Therefore, the higher toxicity of the sample containing these hydrocarbons over time can be attributed to the secondary compounds formed by microbial action. Thus, we conclude that the biodegradation in soil of the studied compounds requires longer periods for the sample toxicity to be decreased with the action of microorganisms.
Resumo em Inglês:Yeast communities were assessed in 14 rivers and four lakes from the Doce River basin in Brazil, during the rainy and dry seasons of the years 2000 and 2001. Water samples were collected at the subsurface in all sites. The following physical and chemical parameters were measured: temperature, dissolved oxygen, pH, electrical conductivity, total phosphorus, ortho-phosphate, ammonium, nitrate, nitrite and total nitrogen and the counts of faecal coliforms and heterotrophic bacteria were carried out to characterize the aquatic environmental sampled. The yeast counts were higher in aquatic environments with the highest counts of coliform and heterotrophic bacteria. These environments receive a high influx of domestic and industrial waste. A total of 317 isolates identified in forty eight yeast species were recorded in the sites sampled and the specie Aureobasidium pullulans were found in eleven out of eighteen sites sampled and some opportunistic pathogens such as the yeast species Candida krusei were isolated only in the polluted rivers with a positive correlation with the biotic and abiotic parameters that indicate sewage contamination.
Resumo em Inglês:Halophiles are excellent sources of enzymes that are not only salt stable but also can withstand and carry out reactions efficiently under extreme conditions. The aim of the study was to isolate and study the diversity among halophilic bacteria producing enzymes of industrial value. Screening of halophiles from various saline habitats of India led to isolation of 108 halophilic bacteria producing industrially important hydrolases (amylases, lipases and proteases). Characterization of 21 potential isolates by morphological, biochemical and 16S rRNA gene analysis found them related to Marinobacter, Virgibacillus, Halobacillus, Geomicrobium, Chromohalobacter, Oceanobacillus, Bacillus, Halomonas and Staphylococcus genera. They belonged to moderately halophilic group of bacteria exhibiting salt requirement in the range of 3-20%. There is significant diversity among halophiles from saline habitats of India. Preliminary characterization of crude hydrolases established them to be active and stable under more than one extreme condition of high salt, pH, temperature and presence of organic solvents. It is concluded that these halophilic isolates are not only diverse in phylogeny but also in their enzyme characteristics. Their enzymes may be potentially useful for catalysis under harsh operational conditions encountered in industrial processes. The solvent stability among halophilic enzymes seems a generic novel feature making them potentially useful in non-aqueous enzymology.
Resumo em Inglês:This study evaluated 26 pigeonpea rhizobial isolates according to their cultural characteristics, intrinsic antibiotic resistance, salt and temperature tolerance, carbon source utilization and amylolytic activity. The cultural characterization showed that the majority of them presented the ability to acidify the YMA. Among the 27 isolates evaluated, 25 were able to grow when incubated at 42° C and 11 showed tolerance to 3% (w/v) of NaCl in YMA medium. The patterns of carbon sources utilization was very diverse among the isolates. It was observed the capacity of three strains to metabolize all the carbon sources evaluated and a total of 42% of the bacterial isolates was able to grow in the culture medium supplemented with at least, six carbon sources. The carbon sources mannitol (control) and sucrose were metabilized by all isolates evaluated. The profile of intrinsic resistance to antibiotics showed that the isolates were mostly resistant to streptomycin and ampicillin, but susceptible to kanamycin and chloranphenicol. High amylolytic activity of, at least, four isolates was also demonstrated, especially for isolated 47.3b, which showed the highest enzymatic index. These results indicate the metabolic versatility of the pigeonpea rhizobia, and indicates the isolate 47.3b to further studies regarding the amylase production and characterization.
Resumo em Inglês:Levan is an exopolysaccharide of fructose primarily linked by β-(2→6) glycosidic bonds with some β-(2→1) branched chains. Due to its chemical properties, levan has possible applications in both the food and pharmaceutical industries. Bacillus subtilis is a promising industrial levan producer, as it ferments sucrose and has a high levan-formation capacity. A new strain of B. subtilis was recently isolated from Japanese food natto, and it has produced levan in large quantities. For future pharmaceutical applications, this study aimed to investigate the effects of levan produced by B. subtilis Natto, mainly as potential hypoglycemic agent, (previously optimized with a molecular weight equal to 72.37 and 4,146 kDa) in Wistar male rats with diabetes induced by streptozotocin and non-diabetic rats and to monitor their plasma cholesterol and triacylglycerol levels. After 15 days of experimentation, the animals were sacrificed, and their blood samples were analyzed. The results, compared using analysis of variance, demonstrated that for this type of levan, a hypoglycemic effect was not observed, as there was no improvement of diabetes symptoms during the experiment. However, levan did not affect any studied parameters in normal rats, indicating that the exopolysaccharide can be used for other purposes.
Resumo em Inglês:Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr), silver (Ag) and mercury (Hg). Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%). Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerantBacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr). Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria.
Resumo em Inglês:Suid herpesvirus 1 (SuHV-1) is the causative agent of pseudorabies (PR), a disease of great importance due to the huge losses it causes in the swine industry. The aim of this study was to determine a method for genotyping SuHV-1 based on partial sequences of the gene coding for glycoprotein C (gC) and to elucidate the possible reasons for the variability of this region. A total of 109 gCsequences collected from GenBank were divided into five major groups after reconstruction of a phylogenetic tree by Bayesian inference. The analysis showed that a portion of gC (approximately 671 bp) is under selective pressure at various points that coincide with regions of protein disorder. It was also possible to divide SuHV-1 into five genotypes that evolved under different selective pressures. These genotypes are not specific to countries or continents, perhaps due to multiple introduction events related to the importation of swine.
Resumo em Inglês:The role of rhinovirus asymptomatic infections in the transmission among close contacts subjects is unknown. We tested health care workers, a pair of one child and a family member and immunocompromised patients (n =191). HRV were detected on 22.9% symptomatic and 3.6% asymptomatic cases suggesting lower transmission among contacts.
Resumo em Inglês:The epidemiological relationships between isolated Staphylococcus aureus strains in milk samples of dairy cows, reagent to California Mastitis Test, individual and group milk was demonstrated in different sites of the production fluxogram, in 12 milk-producing farms in the Gameleira region, municipality of Sacramento MG Brazil, so that localization and transmission modes may be identified. Two hundred and forty-four strains out of 446 samples collected at several sites were isolated and bio-chemically characterized as coagulase-positive staphylococcus. Specific chromosome DNA fragment of the species Staphylococcus aureus was amplified to 106 strains and 103 underwent (PFGE). Samples' collection sites with the highest isolation frequency of Staphylococcus aureus strains comprised papillary ostia (31.1%), CMT-reagent cow milk (21.7%), mechanical milking machines' insufflators (21,7%), milk in milk pails (6.6%) and the milk in community bulk tanks (5.6%). Genetic heterogeneity existed among the isolated 103 Staphylococcus aureus strains, since 32 different pulse-types were identified. Pulse-type 1 had the highest similarity among the isolated strains within the different sites of the milk-production fluxogram. Highest occurrence of pulsetype 1 isolates of Staphylococcus aureus strains was reported in samples collected from the papillary ostia (10.6%), followed by milk samples from CMT-reagent dairy cows (5.8%) and mechanical milking machine insufflators (3.8%). The above shows the relevance of these sites in the agents' transmission mechanism within the context of the farms investigated.