Resumo em Inglês:

The antimicrobial susceptibility of 64 strains of S. pneumoniae obtained from three hospitals in Porto Alegre, Brazil, isolated between 2004 and 2005, was determined, using the agar-dilution method. The prevalence of resistant (intermediate and full resistance) strains to trimethoprim/sulphamethoxazole, penicillin, tetracycline, erythromycin, chloramphenicol, and ceftriaxone were 68%, 28%, 18%, 15%, 3%, and 1%, respectively. All strains were susceptible to vancomycin. Among 18 penicillin-resistant strains, 7 were resistant to at least two other antimicrobial drugs. All erythromycin-resistant strains, except one, contained the erm(B) and/or mef(A/E) genes, with a predominance of the former. The resistance rate to penicillin and erythromycin in Porto Alegre remained stable. The combination of trimethoprim/ sulphamethoxazole should not be recommended to treat pneumococcal infections, because of the high rate of resistant strains.

Resumo em Inglês:

Urogenital infections affect millions of people every year worldwide. The treatment of these diseases usually requires the use of antimicrobial agents, and more recently, the use of probiotic lactic acid bacteria (LAB) cultures for the management of vaginal infections has been extensively studied. In this work, 11 vaginal lactobacilli isolates, previously obtained from healthy patients, were studied to screen microorganisms with probiotic properties against Candida spp. The LAB were tested for their ability of auto-aggregation, coaggregation with C. albicans, C. glabrata, C. krusei, and C. tropicalis, adhesion to Caco-2 epithelial cells and production of lactic acid and hydrogen peroxide (H2O2). All lactobacilli isolates tested were able to auto-aggregate (ranging from 25.3% to 75.4% assessed at 4 hours of incubation) and to co-aggregate with the four Candida species into different degrees; among them L. crispatus showed the highest scores of coaggregation. The highest amount of lactic acid was produced by L. salivarius (13.9 g/l), followed by L. johnsonii (6.5 g/l), L. acidophilus (5.5 g/l), and L. jensenii (5.4 g/l). All isolates produced H2O2 , but the highest levels (3 -10 mg/l) were observed for L. acidophilus, L. crispatus, L. gasseri, L. johnsonii, and L. vaginalis. Only L. agilis, L. jensenii, L. johnsonii and L. ruminus were able to adhere to epithelial Caco-2 cells. Among the isolates evaluated, L agilis, L. jensenii, L. johnsonii, and L. ruminus exhibited simultaneously several desirable properties as potential probiotic strains justifying future studies to evaluate their technological properties in different pharmaceutical preparations for human use.

Resumo em Inglês:

Due to the fact the incubation conditions may influence the microbiological evaluation of water for dialysis, the objective of the present study was the comparison of the efficiency of R2A and PCA media in the enumeration of heterotrophic bacteria in 193 samples of water collected in dialysis clinics from 12 cities in São Paulo, between October and December 2007. Results showed counts significantly greater in R2A, suggesting that enumeration should be carried out in R2A, suggesting that enumeration should be carried out in R2A agar associated with longer incubation times, because of the greater sensitivity.

Resumo em Inglês:

Patients suffering of diseases that affect central nervous system may be considered more susceptible to the infectious diseases of mouth. Sixty-nine patients suffering of cerebral palsy, Down's syndrome and metal retardation were submitted to saliva examination for the presence of Candida spp. before and after a procedure of dental cleaning. The isolates were submitted to assay for verifying phospholipase production. 55.10% of the patients provided isolation of Candida spp. The frequency of isolation obtained before dental procedure was: C. albicans (83.33%), C. krusei (8.33%) and C. kefyr, C. parapsilosis and C. glabrata (2.78% each). The frequency after the procedure was: C. albicans (68.57%), C. parapsilosis (11.43%), C. krusei and C. kefyr (8.57% each) and Candida glabrata (2.86%). We verified significantly difference (p < 0.01) between populations obtained at the two examinations. Phospholipase production was verified only among C. albicans strains and the proportion of producers was higher when testing isolates obtained after dental cleaning procedure. Studies focused on Candida spp. isolation are useful for better comprehension of the role of these yeasts on the oral flora from patients with cerebral palsy, Down's syndrome and metal retardation.

Resumo em Inglês:

This study aimed at determining prevalence and resistance profile of Gram-negative bacilli isolated from nasopharynx of children attending day-care centers in Goiânia (Brazil). P. aeruginosa (100.0%), E. coli (50.0%), K. pneumoniae (35.3%), and E. aerogenes (16.7%) were the most frequent multi-drug resistant microorganisms isolated. No production of ESBL was detected.

Resumo em Inglês:

This study aimed to identify the constituents of the essential oil from Hyptis suaveolens (L.) leaves using a Gas Chromatograph -Mass Spectrometer and assess its inhibitory effect on some potentially pathogenic Aspergilli (A. flavus, A. parasiticus, A. ochraceus, A. fumigatus and A. niger). Eucaliptol (47.64 %) was the most abundant component in the oil, followed for gama-ellemene (8.15 %), beta-pynene (6.55 %), (+)3-carene (5.16 %), trans-beta-cariophyllene (4.69 %) and germacrene (4.86 %). The essential oil revealed an interesting anti-Aspergillus property characterized by a Minimum Inhibitory Concentration and Minimum Fungicidal Concentration of 40 and 80 µL/mL, respectively. The oil at 80 and 40 µL/mL strongly inhibited the mycelial growth of A. fumigatus and A. parasiticus along 14 days. In addition, at 10 and 20 µL/mL the oil was able to cause morphological changes in A. flavus as decreased conidiation, leakage of cytoplasm, loss of pigmentation and disrupted cell structure suggesting fungal wall degeneration. These findings showed the interesting anti-Aspergillus property of H. suaveolens leaves essential oil supporting its possible rational use as alternative source of new antifungal compounds to be applied in the aspergillosis treatment.

Resumo em Inglês:

In this study we report the first isolation of VanA-type vancomycin-resistant Enterococcus faecalis strains from two different patients hospitalized in the same intensive care unit at the hospital of Universidade Federal do Triângulo Mineiro (UFTM), Uberaba, Minas Gerais, Brazil.

Resumo em Inglês:

Influence of iron-depletion on twitching motility and quorum sensing (QS) system in P. aeruginosa was evaluated. The results demonstrated iron-depletion can retard biofilm formation and increase the twitching motility and expression of QS-related genes, suggesting a potential interaction between twitching motility and QS system in P. aeruginosa biofilm formation.

Resumo em Inglês:

This study evaluated the in vitro susceptibility of C. albicans, C. dubliniensis, C. tropicalis and C. krusei to photodynamic therapy (PDT) induced by Photogem® and light emitting diode (LED). Suspensions of each Candida strain were treated with three photosensitizer (PS) concentrations (10, 25 and 50 mg/L) and exposed to 18.0, 25.5 and 37.5 J/cm² LED light fluences (λ ~ 455 nm). Control suspensions were treated only with PS concentrations, only exposed to the LED light fluences or not exposed to LED light or PS. Sixteen experimental conditions were obtained and each condition was repeated three times. From each sample, serial dilutions were obtained and aliquots were plated on Sabouraud Dextrose Agar. After incubation of plates (37 ºC for 48 hours), colonies were counted (cfu/mL) and the data were statistically analyzed by ANOVA and the Tukey test (α=0.05). Complete killing of C. albicans was observed after 18.0 J/cm² in association with 50 mg/L of PS. C. dubliniensis were inactivated after 18.0 J/cm² using 25 mg/L of PS. The inactivation of C. tropicalis was observed after photosensitization with 25 mg/L and subsequent illumination at 25.5 J/cm². For C. krusei, none of the associations between PS and light resulted in complete killing of this species. PDT proved to be effective for the inactivation of C. albicans, C. dubliniensis and C. tropicalis. In addition, reduction in the viability of C. krusei was achieved with some of the PS and light associations.

Resumo em Inglês:

A prospective analysis of active Human Cytomegalovirus infection (HCMV) was conducted on 33 pediatric renal or hematopoietic stem cell post-transplant patients. The HCMV-DNA positive samples were evaluated for the prevalence of different gB subtypes and their subsequent correlation with clinical signs. The surveillance of HCMV active infection was based on the monitoring of antigenemia (AGM) and on a nested polymerase chain reaction (N-PCR) for the detection of HCMV in the patients studied. Using restriction analysis of the gB gene sequence by PCR-RFLP (Restriction Fragment Length Polymorphism), different HCMV strains could be detected and classified in at least four HCMV genotypes. Thirty-three pediatric recipients of renal or bone marrow transplantation were monitored. Twenty out of thirty-three (60.6%) patients demonstrated active HCMV infection. gB1 and gB2 genotypes were more frequent in this population. In this study, we observed that gB2 had correlation with reactivation of HCMV infection and that patients with mixture of genotypes did not show any symptoms of HCMV disease. Future studies has been made to confirm this.

Resumo em Inglês:

Food handlers, an important factor in food quality, may contain bacteria that are able to cause foodborne disease. The present study aimed to research coagulase-negative (CNS) and -positive staphylococci (CPS) in 82 food handlers, analyzing nasal and hand swabs, with identification of 62 CNS (75.6%) and 20 CPS strains (24.4%). Staphylococcal enterotoxins genes were investigated by PCR. In 20 CPS strains, 19 were positive for one or more genes. The percentage of CNS presenting genes for enterotoxins was high (46.8%). Despite of the staphylococcal species, the most common gene was sea (35.4%), followed by seh and sej (29.2%). The detection of new staphylococcal enterotoxins (SEs) genes showed a higher pathogenic potential in this genus. The presence of these gene points out the importance of CNS not only as contaminant bacteria but also as a pathogen.

Resumo em Inglês:

The use of antibiotics in agriculture is limited when compared to their applications in human and veterinary medicine. On the other hand, the use of antimicrobials in agriculture contributes to the drug resistance of human pathogens and has stimulated the search for new antibiotics from natural products. Essential oils have been shown to exert several biological activities including antibacterial and antifungal actions. The aim of this study was to determine the activity of 28 essential oils from medicinal plants cultivated at CPMA (Medicinal and Aromatic Plants Collection), CPQBA/UNICAMP, against Colletotrichum gloeosporioides (Penz.) Sacc., the anthracnose agent in yellow passion fruit (Passiflora edulis Sims f. flavicarpa Deg), as well as evaluating their effect in the control of post-harvest decay. The oils were obtained by water-distillation using a Clevenger-type system and their minimal inhibitory concentrations (MIC) determined by the micro-dilution method. According to the results, 15 of the 28 essential oils presented activity against Colletotrichum gloeosporioides, and the following four oils presented MIC values between 0.25 and 0.3 mg/mL: Coriandrum sativum, Cymbopogon citratus, Cymbopogon flexuosus and Lippia alba. The evaluation of Cymbopogon citratus essential oil in the control of post-harvest decay in yellow passion fruit showed that the disease index of the samples treated with the essential oil did not differ (P < 0.05) from that of the samples treated with fungicide. The present study shows the potential of Cymbopogon citratus essential oil in the control of the anthracnose agent in yellow passion fruit.

Resumo em Inglês:

This study investigated the antimicrobial activity of Enterococcus faecium FAIR-E 198 against Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. Using the critical-dilution method, the bacteriocin produced by E. faecium FAIR-E 198 inhibited all L. monocytogenes strains evaluated (1,600 to 19,200 AU mL-1). However, none of the B. cereus and S. aureus strains investigated were inhibited. The maximum activity of this bacteriocin (800 AU mL-1) was observed in MRS broth, while the activity in milk was 100 AU mL-1. In the co-cultivation test in milk, B. cereus K1-B041 was reduced to below the detection limit (1.00 log CFU mL-1) after 48 h. E. faecium reduced the initial L. monocytogenes Scott A population by 1 log CFU mL-1 after 3 h at 35ºC. However, the pathogen regained growth, reaching 3.68 log CFU mL-1 after 48 h. E. faecium did not influence the growth of S. aureus ATCC 27154 during the 48 h of co-cultivation. Therefore, it can be concluded that the effectiveness of the antimicrobial activity of E. faecium FAIR-E 198 is strictly related to the species and strain of the target microorganism and to the culture medium.

Resumo em Inglês:

In this study, we investigated the binding ability of Saccharomayces cerevisiae to aflatoxin in pistachio nuts. The obtained results indicate that S. cerevisiae has an aflatoxin surface binding ability of 40% and 70% (with initial aflatoxin concentrations of 10 and 20 ppb) in the exponential phase. Acid treatments increase this ability to approximately 60% and 73% for the two concentrations of aflatoxin, respectively. Heat treatments also enhance surface binding to 55% and 75%, respectively. Binding appears to be a physical phenomenon that saturates within the first 2-3 hours of the process. The obtained results indicate that yeast immobilization for toxin reduction on aflatoxin-contaminated pistachios had no effect on qualitative characteristics, such as color, texture, and peroxide value. Yeast cells, viable or nonviable, are effective for aflatoxin binding, and this property could lead to a promising solution to aflatoxin contamination in high-risk foods.

Resumo em Inglês:

The proteolytic activity of Pseudomonas fluorescens 07A was investigated, and was optimal on tryptone-calcium medium. N-acyl-homoserine lactones (AHLs) were not detected on supernatants of late-exponential and stationary-phase culture broths. Synthetic AHLs or bacterial cell extracts added to the medium did not influence growth or proteolytic activity suggesting that quorum sensing might not regulate protease production in this strain.

Resumo em Inglês:

An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 ºC and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM) after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential.

Resumo em Inglês:

To evaluate the effect of two bacterial strains isolated from Artemia cysts and yeast (Candida utilis) on the survival, growth and total biomass production of its larvae, challenge tests were performed with Candida utilis, Pseudomonas stutzeri and Pasteurella haemolityca. In addition, a pathogenic strain of Vibrio alginolyticus was tested for comparative purposes. Pseudomonas stutzeri and Candida utilis have no impact on survival, but enhance growth and total biomass production of the larvae. However, we noted that Pasteurella haemolityca affect negatively Artemia larvae. The adhesion and antagonism assay demonstrates that Candida utilis and Pseudomonas stutzeri are fairly adherent and play an important role in the enhancement of the protection of Artemia culture against pathogens. On the basis of these results, it's suggested that it's possible to use Candida utilis and Pseudomonas stutzeri, potential candidates, as probiotic for the culture of Artemia larvae.

Resumo em Inglês:

The aim of this study was to evaluate the in vitro activity of the essential oil extracted from Origanum vulgare against sixteen Candida species isolates. Standard strains tested comprised C. albicans (ATCC strains 44858, 4053, 18804 and 3691), C. parapsilosis (ATCC 22019), C. krusei (ATCC 34135), C. lusitaniae (ATCC 34449) and C. dubliniensis (ATCC MY646). Six Candida albicans isolates from the vaginal mucous membrane of female dogs, one isolate from the cutaneous tegument of a dog and one isolate of a capuchin monkey were tested in parallel. A broth microdilution technique (CLSI) was used, and the inoculum concentration was adjusted to 5 x 10(6) CFU mL-1. The essential oil was obtained by hydrodistillation in a Clevenger apparatus and analyzed by gas chromatography. Susceptibility was expressed as Minimal Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC). All isolates tested in vitro were sensitive to O. vulgare essential oil. The chromatographic analysis revealed that the main compounds present in the essential oil were 4-terpineol (47.95%), carvacrol (9.42%), thymol (8.42%) and □-terpineol (7.57%). C. albicans isolates obtained from animal mucous membranes exhibited MIC and MFC values of 2.72 µL mL-1 and 5 µL mL-1, respectively. MIC and MFC values for C. albicans standard strains were 2.97 µL mL-1 and 3.54 µL mL-1, respectively. The MIC and MFC for non-albicans species were 2.10 µL mL-1 and 2.97 µL mL-1, respectively. The antifungal activity of O. vulgare essential oil against Candida spp. observed in vitro suggests its administration may represent an alternative treatment for candidiasis.

Resumo em Inglês:

Bovine herpesvirus type 5 (BoHV-5) is the agent of meningoencephalitis, an important disease of cattle in South America. The neuropathogenesis of BoHV-5 infection is poorly understood and most previous research focused on the role of envelope glicoproteins in neurovirulence. Thymidine kinase (TK) is a viral enzyme necessary for virus replication in neurons and, therefore, represents a potential target for virus attenuation. The selection and characterization of BoHV-5 variants resistant to the nucleoside analog brivudin (BVDU), which selects TK-defective viruses is here described. Several BVDU-resistant clones were obtained after multiple passages in tissue culture in the presence of BVDU and one clone (BoHV-5/R-27) was further characterized. The selected clone replicated to similar titers and produced plaques with similar size and morphology to those of wild-type virus (SV507/99). The genetic stability of the resistant virus was demonstrated after ten passages in cell culture in the absence of the drug. Moreover, the drug-resistant virus showed reduced virulence in a rabbit model: virus inoculation in four rabbits did not result in disease, in contrast with 75% morbidity (3/4) and 50% mortality (2/2) among rabbits inoculated with the parental virus. These results demonstrate that BoHV-5 is sensitive to BVDU and that drug-resistant mutants can be readily selected upon BVDU treatment. BVDU-resistant mutants, likely defective in TK, retained their ability to replicate in tissue culture yet were attenuated for rabbits. This strategy to obtain TK-defective BoHV-5 may be useful to study the role of TK in BoHV-5 neuropathogenesis and for vaccine development.

Resumo em Inglês:

Mastitis is considered to be the most economically costly disease affecting the dairy industry. Regular dosage of animals with antibiotics, including use of prophylactic concentrations, may select for resistant strains. The purpose of this study was to determine the mode of action of a new bacteriocin (macedocin ST91KM), to evaluate the antimicrobial resistance of mastitis pathogens to antibiotics commonly used in treatment remedies, and to introduce the possible use of an alternative antimicrobial agent. The bacteriocin macedocin ST91KM, produced by Streptococcus gallolyticus subsp. macedonicus ST91KM, is bactericidal to Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis and Staphylococcus aureus associated with mastitis infections, including strains resistant to methicillin and oxacillin. Sensitive cells were deformed and secreted nucleotides, K+ and β-galactosidase when exposed to macedocin ST91KM. Adsorption of the peptide to target cells decreased in the presence of solvents, suggesting that receptors on the cell surfaces have lipid moieties. No adsorption was recorded in the presence of MgCl2, KI and Na2CO3, suggesting that ionic strength plays an important role. A teat seal preparation containing macedocin ST91KM effectively released the peptide and inhibited the growth of S. agalactiae. Macedocin ST91KM could form the basis for alternative dry cow therapy to prevent mastitis infections in dairy cows as it is effective against pathogens that display resistance to conventional antibiotic therapy.

Resumo em Inglês:

The clinical, anatomical and histopatological findings of glanders diagnosis in donkeys in the state of Pernambuco-Brazil are reported. The animals were euthanized and necropsied, and evaluated for lesions in respiratory and lymphatic systems, confirming the disease by isolation of Burkholderia mallei and Strauss test.

Resumo em Inglês:

The main goal of this study was to evaluate the prevalence of leptospirosis among field rodents of Tiruchirappalli district, Tamil Nadu, India. In total 35 field rats were trapped and tested for seroprevalence by the microscopic agglutination test (MAT). Isolation of leptospires was performed from blood and kidney tissues and characterized to serovar level. Genomospecies identification was carried out using 16S rRNA and lipL32 gene sequencing. The molecular phylogeny was constructed to find out species segregation. Seroprevalence was about 51.4 %, and the predominant serovars were Autumnalis, Javanica, Icterohaemorrhagiae and Pomona. Two isolates from the kidneys were identified as serovar Javanica of Serogroup Javanica, and sequence based molecular phylogeny indicated these two isolates were Leptospira borgpetersenii.

Resumo em Inglês:

The antibacterial potential of leaf's essential oil (EO) from Brazilian pepper tree (Schinus terebinthifolius Raddi) against staphylococcal isolates from dogs with otitis externa was evaluated. The minimum inhibitory concentration of EO ranged from 78.1 to 1,250 fg/mL. The oil was analyzed by GC and GC/MS and cytotoxicity tests were carried out with laboratory animals.

Resumo em Inglês:

Lovastatin, an inhibitor of HMG-CoA reductase, was produced by solid state fermentation (SSF) using a strain of Aspergillus terreus UV 1718. Different solid substrates and various combinations thereof were evaluated for lovastatin production. Wheat bran supported the maximum production (1458 ± 46 µg g-1 DFM) of lovastatin. Response surface methodology (RSM) was applied to optimize the medium constituents. A 2(4) full-factorial central composite design (CCD) was chosen to explain the combined effects of the four medium constituents, viz. moisture content, particle size of the substrate, di-potassium hydrogen phosphate and trace ion solution concentration. Maximum lovastatin production of 2969 µg g-1 DFM was predicted by the quadratic model which was verified experimentally to be 3004 ± 25 µg g-1 DFM. Further RSM optimized medium supplemented with mycological, peptone supported highest yield of 3723.4±49 µg g-1 DFM. Yield of lovastatin increased 2.6 fold as with compared to un-optimized media.

Resumo em Inglês:

L-asparaginase is an anti-neoplastic agent used in the lymphoblastic leukaemia chemotherapy. In the present study a novel strain, Streptomyces gulbargensis was explored for the production of extra-cellular L-asparaginase using groundnut cake extract. The optimum pH, temperature, inoculum size and agitation speed for enzyme production were pH 8.5, 40ºC, 1x10(8)spores/ml and 200 rev/min respectively. Maltose (0.5%) and L-asparagine (0.5%) proved to be the best carbon and nitrogen sources respectively. The enzyme was purified 82.12 fold and the apparent molecular weight of the enzyme was found to be 85 kDa. The optima pH and temperature for the enzyme were 9.0 and 40ºC respectively. The enzyme was more stable at the alkaline pH than at the acidic one and it retained 55% of the activity at 80ºC for 60 min.

Resumo em Inglês:

This study was aimed at producing protease and lipase simultaneously on a common medium by Bacillus licheniformis VSG1, which was isolated from a tannery effluent. The effect of media composition with respect to protein source, lipid source and emulsifier on the production of protease and lipase was analysed. Both those enzymes were produced under optimized conditions like pH, temperature and incubation time. The enzyme mixture comprising of both protease and lipase was purified by ammonium sulphate precipitation, dialysis and gel filtration chromatography to obtain 20-fold pure enzymes. The purified enzyme mixture was characterized to determine the optimum pH and temperature of protease and lipase, the response of the enzymes to inhibitors, additives and solvents. The molecular weight of both the enzymes was determined as 40 kDa on SDS-PAGE. The concomitant production of protease and lipase and the purification of both the enzymes in a single mixture have industrial significance, as many industrial processes use both protease and lipase together.

Resumo em Inglês:

Aspergillus oryzae IPT-301, previously reported as a β-fructofuranosidase producing microorganism, was successfully mutated using UV irradiation at 253.7 nm followed by the screening of survivors resistant to certain stress conditions. Strains were first subjected to the β-fructofuranosidase activity assay using a portion from the colony grown in Petri dish as the enzyme source. Seven mutants with fructofuranosidase activity values relative to the parent culture between 140 -190% were selected from survivors grown at temperature of 40ºC or 0.018% (w/v) sodium dodecyl sulfate concentration. They were cultivated on a rotary shaker to characterize mycelium and extracellular fructosyltransferase activities. Three mutants named IPT-745, IPT-746 and IPT-748 showed the highest amount of mycelium activity whose values increased 1.5 -1.8 fold, compared with the parent strain. It was found that more than 55% of total enzyme activity (mycelium- plus extracellular- activity) from these strains was detected in the mycelium fraction. Only one mutant, IPT-747, exceeded the amount of extracellular enzyme exhibited by the parent strain (1.5 times). This mutant also showed the highest value of total fructosyltransferase activity.

Resumo em Inglês:

Feather waste is generated in large amounts as a by-product of commercial poultry processing. This residue is almost pure keratin, which is not easily degradable by common proteolytic enzymes. Eight strains of Bacillus, isolated from decomposing feathers were tested for the hydrolysis of feather wastes in the laboratory. Among these strains, Bacillus cereus KB043 was the best feather degrading organism when grown on basal medium containing 1% hen feather as sole source of carbon and nitrogen. It caused 78.16 ± 0.4 % degradation with a significant release of soluble protein (1206.15 ± 14.7 µg mL-1) and cysteine (20.63 ± 0.4 µg mL-1) in the cultivation fluid. The strain also showed the highest level of keratinase activity (39.10 ± 0.4 U mL-1). These data indicates that the Bacillus cereus KB043 could be useful in management of poultry wastes.

Resumo em Inglês:

The aim of this study was to characterize rhizobial isolates from Cratylia mollis Mart. ex Benth, Calliandra depauperata Benth. and Mimosa tenuiflora (Willd.) Poir. by means of rhizobial colonies morphology and restriction analysis of the 16S ribosomal gene (16S rDNA-ARDRA). Nodules were collected in the field and from plants cultivated in a greenhouse experiment using Caatinga soil samples. Sixty seven isolates were described by morphological analysis. Forty seven representative isolates were used for ARDRA analysis using seven restriction enzymes. We observed high diversity of both slow and fast-growing rhizobia that formed three morpho-physiological clusters. A few fast-growing isolates formed a group of strains of the Bradyrhizobium type; however, most of them diverged from the B. japonicum and B. elkanii species. Cratylia mollis nodule isolates were the most diverse, while all Mimosa tenuiflora isolates displayed fast growth with no pH change and were clustered into groups bearing 100% similarity, according to ARDRA results.

Resumo em Inglês:

Sulfentrazone is amongst the most widely used herbicides for treating the main crops in the State of São Paulo, Brazil, but few studies are available on the biotransformation of this compound in Brazilian soils. Soil samples of Rhodic Hapludox soil were supplemented with sulfentrazone (0.7 µg active ingredient (a.i.) g-1 soil) and maintained at 27ºC. The soil moisture content was corrected to 30, 70 or 100 % water holding capacity (WHC) and maintained constant until the end of the experimental period. Herbicide-free soil samples were used as controls. Another experiment was carried out using soil samples maintained at a constant moisture content of 70% WHC, supplemented or otherwise with the herbicide, and submitted to different temperatures of 15, 30 and 40º C. In both experiments, aliquots were removed after various incubation periods for the quantitative analysis of sulfentrazone residues by gas chromatography. Herbicide-degrading microorganisms were isolated and identified. After 120 days a significant effect on herbicide degradation was observed for the factor of temperature, degradation being higher at 30 and 40º C. A half-life of 91.6 days was estimated at 27º C and 70 % WHC. The soil moisture content did not significantly affect sulfentrazone degradation and the microorganisms identified as potential sulfentrazone degraders were Nocardia brasiliensis and Penicillium sp. The present study enhanced the prospects for future studies on the bio-prospecting for microbial populations related to the degradation of sulfentrazone, and may also contribute to the development of strategies for the bioremediation of sulfentrazone-polluted soils.

Resumo em Inglês:

The measures of most-probable-number and restriction fragment length polymorphism analysis were used to analyze the abundance and diversity of ammonia-oxidizing bacteria in sediment of a Chinese shallow eutrophic urban lake (Lake Yuehu). Among the 5 sampling sites, ammonia concentration in interstitial water was positively proportional not only to the content of organic matter, but also to ammonia-oxidizing bacteria numbers (at a magnitude of 10(5) cells g-1 dry weight) in sediment significantly. Furthermore, the diversity of ammonia-oxidizing bacteria were determined by means of PCR primers targeting the amoA gene with five gene libraries created and restriction pattern analysis. The 13 restriction patterns were recorded with 4 ones being common among all sampling sites. The 8 restriction patterns including 4 unique ones were found at the site with the highest NH4+ concentrations in interstitial water, while, there were only common patterns without unique ones at the site with the lowest NH4+ concentrations in interstitial water. Phylogenetic analysis showed that the amoA fragments retrieved belong to Nitrosomonas oligotropha & ureae lineage, N. europaea lineage, N. communis lineage and Nitrosospira lineage, most of which were affiliated with the genus Nitrosomonas. The N. oligotropha & ureae-like bacteria were the dominant species. Thus, the abundance and diversity of sediment AOB is closely linked to ammonium status in eutrophic lakes.

Resumo em Inglês:

Biofouling of membranes demands costly periodic cleaning and membrane replacement. A sustainable and environmentally friendly solution for maintenance is not available and would be of great interest for many purposes including economical. As complex biofilm formation by environmental strains is the major cause of biofouling and biofilm formation in most cases are controlled by N-Acylhomoserine lactone (AHL)mediated Quorum Sensing (QS). An effort was made to understand the appropriateness of 2(5H)-furanone, to use against biofouling of membranes. QS inhibition activity by 2(5H)-furanone was studied using bioindicator strains and known AHLs of different acyl chain lengths. The biofilm inhibition was studied by growth analysis on polystyrene plate of Aeromonas hyrdrophila, an environmental biofilm strain isolated from a bio-fouled reverse osmosis (RO) membrane. Results showed a QS inhibition activity against a wide range of AHLs and also biofilm formation by 2(5H)-furanone, which is believed to act as a potential quorum inhibition agent in a bacterial biofilm community.

Resumo em Inglês:

The contamination of ecosystems with heavy metals is an important issue in current world and remediation technologies should be in according to environmental sustainability concept. Bioemulsifier are promising agents to be used in metal removal and could be effective to many applications in environmental industries. The aims of this work was screening the potential production of bioemulsifier by microorganisms isolated from an oil contaminated mangrove, and evaluate cadmium and zinc removal potential of those strains from a hazardous industrial residue. From that, bioemulsifier-producing bacteria were isolated from urban mangrove sediments. Four isolates were identified as Microbacterium sp by 16S rRNA analysis and were able to reduce up to 53.3% of culture medium surface tension (TS) when using glucose as carbon and energy source and 20.2% when sucrose was used. Suspensions containing bioemulsifier produced by Microbacterium sp. strains show to be able to remove cadmium and zinc from contaminated industrial residue, and its ability varied according carbon source. Significant differences in metal removal were observed by all strains depending on the carbon source. When glucose was used, Cd and Zn removal varied from 17 to 41%, and 14 to 68%, respectively. However, when sucrose was used it was observed only 4 to a maximum of 15% of Cd removal, and 4 to 17% of Zn removal. When the same tests were performed after ethanol precipitation, the results were different: the percentages of removal of Zn (7-27%) and Cd (14-32%) were higher from sucrose cultures. This is the first report of heavy metals removal by bioemulsifier from Microbacterium sp.

Resumo em Inglês:

Myrothecium roridum and M. verrucaria are two plant pathogenic species causing foliar spots in a large number of cultivated plants. This paper aims to study the causal agents of foliar spots in vegetable crops (sweet pepper, tomato and cucumber), ornamental plants (Spathiphyllum wallisii, Solidago canadensis, Anthurium andreanum, Dieffenbachia amoena) and a solanaceous weed plant (Nicandra physaloides). Most of the isolates were identified as M. roridum; only the isolate 'Myr-02' from S. canadensis was identified as M. verrucaria. All the isolates were pathogenic to their original plant hosts and also to some other plants. Some fungicides were tested in vitro against an isolate of M. roridum and the mycelial growth recorded after seven days. Fungicides with quartenary ammonium, tebuconazole and copper were highly effective in inhibiting the mycelial growth of M. roridum. This paper confirms the first record of M. roridum causing leaf spots in sweet pepper, tomato, Spathiphyllum, Anthurium, Dieffenbachia and N. physaloides in Brazil. We also report M. roridum as causal agent of cucumber fruit rot and M. verrucaria as a pathogen of tango plants.

Resumo em Inglês:

Sclerotium rolfsii (Sacc.) is a serious plant pathogenic fungus and lacks perfect (basidial) stage in production. Protoplast fusion technology was employed to reconstruct fusants from this fungus. Two strains designated as A and R were used. Maximum protoplast yields of 3.8x10(5) /g mycelia and 2.8x10(5) /g mycelia were formed in strains A and R respectively. Osmotic stabilizer sucrose 1M gave maximum yield. Lysing enzyme at the rate of 15mg/ml was found best for yield. Fusion of protoplasts from strains A and R was carried out in fusion media containing PEG 4000 30% (w/v) with 0.2mM CaCl2. Four fusants F1, F2, F3 and F4 were recovered. Morphological, physiological and pathogenic characters of fusants were compared with parent strains on carrots, beans and tomato.

Resumo em Inglês:

A development mutant, named V103, was obtained spontaneously from the A strain of A. nidulans. The A strain contains a duplicated segment of chromosome I that has undergone translocation to chromosome II (I → II). It is mitotically unstable and generates phenotypically deteriorated types, some with enhanced stability. The deteriorated variants of A. nidulans show abnormal development, exhibiting slower colony growth, variations in colony pigmentation and changes in conidiophore structure. The alterations observed in the conidiophore include fewer metulae and phialides, further elongation and ramification of these structures, delayed nuclear migration and the presence of secondary conidiophores.