Abstract There is considerable concern about the impact plastic materials have on the environment due to their durability and resistance to degradation. The use of pro-oxidant additives in the polymer films could be a viable way to decrease the harmful effects of these discarded materials. In this study, films of PHBV/PP-co-PE (80/20 w/w) and PHBV/PP-co-PE/add (80/19/1 w/w/w) (with pro-oxidant additive) were employed to verify the influence of the additive on the biodegradation of these films in the soil. These films were obtained by melting the pellets in a press at 180 °C which were buried in soil columns for 3 and 6 months. Some samples were also heated before being buried in soil. The biodegradation is higher for the additive blend buried for 3 months than for the pre-heated blend. After 6 months the blend buried and heated/buried was completely degraded in soil. The effect of the additive, on chain oxidation, is more time-dependant than heat-dependant.

The increased consumption of plastics in the world has been a subject of great concern and special attention by the scientific community. The aim is to promote development of materials that are biodegradable in a shorter time upon disposal in the environment. The most used synthetic plastics are difficult to biodegrade because they are made of long hydrocarbon chains, such as polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), which are hydrophobic and resistant to the action of microbial enzymes. The use of alternative materials (natural polyesters) can minimize the harm to dumps and landfills upon their disposal, because they are susceptible to the action of microorganisms. In this study we evaluated the biodegradation/biodeterioration of PHBV (poly(3-hydroxybutyrate-co-hydroxyvalerate) films, LDPE (low density polyethylene) and the blend of LDPE/PHBV (70/30) by the fungus Paecilomyces variotii, using different methods: optical microscopy (OM), scanning electronic microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR).

This study investigated the biodegradation of blends films of poly(vinyl alcohol)/poly(vinyl chloride) (PVA/PVC) and poly(vinyl alcohol)/poly(caprolactone) (PVA/PCL) blends films prepared with dimethylformamide under a variety of conditions by respirometry, spectrophotometry (FTIR), scanning electron microscopy (SEM), and contact angle. The films were buried in the garden soil and in the soil mixed with the landfill leachate for 120 days at 28ºC. Significant levels of biodegradation were achieved in fairly short incubation times in the soil. The results indicated that PVA was the most biodegradable film in the soil and in the soil with the leachate.

O propósito deste estudo é investigar a biodegradação de filmes de PHB, PP e blenda de PP/PHB (1:1) por microrganismos de águas de rio poluído que recebeu vários tipos de descartes, inclusive de refinaria de petróleo. Os filmes poliméricos foram obtidos por fusão do pó do material a 175 ºC, prensados a 71,3 kgf.cm-2 e resfriados a 25 ºC. Estes filmes foram mantidos em amostras de águas do rio poluído, coletadas antes e após o descarte do efluente da refinaria de petróleo e mantidas em estufa bacteriológica a 28 ºC, durante 120 dias. As mudanças, causadas pela ação microbiana nos filmes, foram analisadas por medidas de perda de massa, infravermelho com transformada de Fourier (FTIR) e microscopia eletrônica de varredura (MEV). Os resultados provaram que a degradação do PHB ocorre tanto na sua fase amorfa como na cristalina, sendo mais significativa na água do rio que recebeu o efluente da refinaria de petróleo, contendo microrganismos reconhecidos como potencialmente capazes de degradar substâncias persistentes no meio ambiente.

The purpose of this study is to investigate the biodegradation of films made with PP, PHB and PP/PHB (1:1) blend caused by microorganisms from polluted river which received several types of waste, including an oil refinery effluent. The films were obtained by melting the powder from the material at 175 ºC, pressed at 71.3 kgf.cm-2 and cooled at 25 ºC. These films were kept in polluted river water samples, collected before and after the discarding of oil refinery waste, and they were kept in the bacteriological incubator at 28 ºC for 120 days. The changes caused by microbial action on the films were analyzed by measurements of weight loss, Fourier transform infrared (FTIR) and scanning electronic microscopy (SEM). The results proved that PHB degradation occurs in amorphous and crystalline phases, being more significant in the river water which received refinery oil waste, containing microorganisms recognized as potentially capable to degrade recalcitrant substances in the environment.

O presente trabalho utilizou formas paramorfogênicas de Neurospora crassa 74A linhagens, na remoção do corante "Erythrosin B". O fungo, induzido química e fisicamente em forma de "pellets", foi usado no estudo da biodegradação deste corante. A cultura fúngica foi crescida em meio contendo o corante, como única fonte de carbono por 2 e 90h de interação. As paredes celulares foram isoladas por um processo de lavagem em água destilada e o micélio fresco foi secado por 12 h a 105ºC, e transformado num pó fino, e analisado em FTIR. O sobrenadante foi analisado através de espectrofotômetro UV-VIS e FTIR. Diferenças significativas no espectro UV-VIS e no FTIR foram observadas entre o controle e o sobrenadante e entre o controle e as paredes coloridas de vermelho e em FTIR no tempo de 2 e 90 h. Algumas bandas foram modificadas sugerindo a possibilidade de uma biodegradação enzimática em função do tempo de contato entre o corante e a biomassa fúngica.

The present work used paramorphic forms of Neurospora crassa 74A to remove erythrosine. The fungus culture was grown in medium containing the dye, as only carbon source for 2 and 90 h of interaction. A washing process using distilled water isolated the cellular mass mycelia was dried for 12 h at 105ºC and transformed in fine powder and analyzed in FTIR. The supernatant was analyzed through spectrophotometer UV-Vis and FTIR. Significant differences in the spectrum of UV-VIS and FTIR were observed between the control and the supernatant and between wall control and the walls colored by red, in FTIR for 2 and 90 h. Some significant bands were modified, suggesting the possibility of enzymatic biodegradation in proportion to the time of contact between the dye and fungal biomass.

Muitos fungos termofílicos são conhecidos como sendo produtores de lipases e o potencial dessas enzimas nas reações de esterificação (reação inversa à hidrólise), há muito tem sido reconhecida. O aspecto do micélio e diversas observações microscópicas foram efetuadas em Thermomyces lanuginosus cultivado em Placas de Petri com meios de culturas YpSs (extrato de levedura + amido + agar) e mais quatro variações na fonte de carbono neste meio. As matérias-primas usadas e avaliadas foram pentaeritritol, ácido oléico e dioleato de pentaeritritol como possíveis fontes de carbono disponíveis ao microrganismo são comumente encontradas na indústria química como intermediários clássicos na síntese de diversos ésteres. Com o crescimento de Thermomyces lanuginosus em todos os meios propostos e a manutenção da capacidade de reprodução mostramos ser esse fungo altamente promissor em futuros trabalhos de biocatálise com microrganismos vivos.

Most thermophilic moulds are known to be lipase producers and the potential for esterification by reversal of lipase hydrolysis has long been recognized. We evaluated the mycelial aspects of T. lanuginosus growing in Petri dishes in YpSs (yeast extract + starch + agar) medium control and four other media based on YpSs containing different carbon source. These raw materials evaluated as carbon sources suppliers for microorganism were pentaerythritol, oleic acid and pentaerythritol dioleate are commonly used in several classic industrial esters synthesis. Thermomyces lanuginosus growed in all studied media and kept its reproduction capacity, showing that this fungus is a promising alternative for future studies of live microorganism's biocatalysts.

The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.

Poli épsilon-caprolactona é um importante polímero biodegradável e miscível com o PVC, um polímero sintético industrial, termo susceptível e não biodegradável. A blenda PVC/PCL é importante quanto a suas propriedades mecânicas e biodegradabilidade. Neste trabalho foi analisada a biomodificação da blenda PVC/PCL pré-tratada com calor (130ºC), através da espectroscopia UV-Vis. Os resultados mostraram que o pré-tratamento com calor pode facilitar a biomodificação em filmes de PVC, mas pode inibir a biomodificação nos filmes da blenda PVC/PCL.

Studies were carried out on biomodification and the pre-heat (130(0)C) influence on Poly (vinyl chloride) / Poly (epsilon-caprolactone) films. The results showed that heat pre-treatment improved the biomodification of PVC films, but it inhibited the biomodification of the PVC/PCL film.

Poli épsilon-caprolactona é um importante polímero biodegradável e miscível com o PVC, um polímero sintético industrial, termo susceptível e não biodegradável. A blenda PVC/PCL é importante em propriedades mecânicas e biodegradabilidade. Neste trabalho, há indicações que há interação dos microrganismos com a superfície polimérica e esta causa mudanças estruturais na blenda PVC/PCL.

Poly (caprolactone) is a famous biodegradable polymer and miscible with PVC, a commercial synthetic polymer, thermal susceptible and non-biodegradable. This blend is important concerning its mechanical properties and biodegradability. In this work, we testified the biomodification of blend films of PVC/PCL by UV-Vis. spectroscopy. The results show us that there is an interaction between the PVC/PCL film and the microrganisms.

Um estudo microscópico foi considerado para analisar a eventual adesão de fungos sobre uma superfície de poliéster-imida presente em fios de cobre esmaltados. A microscopia eletrônica de varredura, permitiu observar nestes biofilmes aderidos, uma alta quantidade de pigmentos, hifas e um arsenal enzimático possivelmente atuando na superfície desta macromolécula. Devido a natureza altamente aromática deste material e traços de derivados fenólicos usados como solventes - que se fazem ainda presentes no polímero já reticulado, uma certa atividade anti-fúngica poderia ser esperada, todavia não foram observadas alterações no crescimento dos microrganismos, bem como no processo de adesão dos fungos. Adicionalmente a este fato, os fios esmaltados revelaram total descaracterização de suas propriedades isolantes. Os estudos visam compreender e avaliar o grande potencial demonstrado pelos fungos que poderia em caráter vindouro, explorado em processos de biodeterioração e biodegradação

A microscopical study was undertaken to analyze the eventual fungi adhesion over a polyester imide surface in enameled copper wires. Scanning electron microscopy allowed to observe in these adhered biofilms, a high amount of pigments, hyphae and its enzymatic arsenal probably acting in the surface of the polymer. Due to the highly aromatic nature of this polyester and the residual phenol derivates still present in the reticulated polymer, an antifungal activity could be expected, but no significant changes were noted in fungal growing and in the adhesion process. Additionally, the wires showed completely failure in all insulation properties. The studies aimed to understand and evaluate the great fungi potential that could be explored in biodeterioration and biodegradation processes.