Biodegradation of Polyester Polyurethane by Endophytic Fungi

Abstract

Bioremediation is an important approach to waste reduction that relies on biological processes to break down a variety of pollutants. This is made possible by the vast metabolic diversity of the microbial world. To explore this diversity for the breakdown of plastic, we screened several dozen endophytic fungi for their ability to degrade the synthetic polymer polyester polyurethane (PUR). Several organisms demonstrated the ability to efficiently degrade PUR in both solid and liquid suspensions. Particularly robust activity was observed among several isolates in the genus Pestalotiopsis, although it was not a universal feature of this genus. Two Pestalotiopsis microspora isolates were uniquely able to grow on PUR as the sole carbon source under both aerobic and anaerobic conditions. Molecular characterization of this activity suggests that a serine hydrolase is responsible for degradation of PUR. The broad distribution of activity observed and the unprecedented case of anaerobic growth using PUR as the sole carbon source suggest that endophytes are a promising source of biodiversity from which to screen for metabolic properties useful for bioremediation.Tremendous increases in the manufacture and consumption of plastics over recent decades have led to numerous ecological and economic concerns. The persistence of synthetic polymers introduced into the environment by human industry poses a major threat to natural ecological systems. The low cost and ease of manufacture have increased global plastic demand more than 150-fold, with the production of 1.5 million tons in 1950 and 245 million tons as of 2006 (21). Despite recognition of the persistent pollution problems posed by plastic, global production is still increasing, with the largest increases expected in developing nations. The sheer volume of plastics produced each year presents a problem for waste disposal systems. The scale of this problem and the recalcitrance of some polymers to degradation necessitate investigation into effective methods for biodegradation of plastics. By gaining an understanding of the mechanisms of polymer degradation, a more efficient technique for the biodegradation of plastic waste can be achieved. To accomplish this goal, researchers need greater knowledge of how compounds are metabolized by existing organisms, an investigation of new organisms with bioremediation potential, and the characterization of novel metabolic capabilities.

Biodegradative Activities of Selected Environmental Fungi on a Polyester Polyurethane Varnish and Polyether Polyurethane Foams

“…Since Poly Lack does not clarify when degraded, it fails as an indicator for quantitative assays, although it provides a means to select possible PE-PU-degrading microorganisms. Therefore, because Impranil clarifies when microorganisms hydrolyze it, it is a visual and reliable method for quantitative analysis (7,16,32,33), and so we chose this substrate for further quantitative degradation experiments.…”

Degradação De Poliuretano Por Fungos: Perspectivas Para Preservação Ambiental

“…Essa coleta, porém, ainda é ineficaz em qualidade e efetividade, dificultando a estimativa do percentual de plástico descartado no país (SCSSF, 2014). Apesar dos danos evidentes causados pelo descarte de plásticos no ambiente, a produção deste poluente ainda continua crescendo, principalmente nos países em desenvolvimento (RUSSELL et al, 2011).…”

“…Segundo (RUSSELL et al, 2011) o fato de micro-organismos endofíticos ocuparem um nicho biológico único, o tecido de plantas, que é rico em complexo de polímeros de carbono, é uma justificativa para a investigação do potencial da ampla capacidade metabólica destes organismos. Trabalhos recentes têm focado na seleção de micro-organismos com habilidade de degradar polímeros sintéticos, objetivando a descoberta de possíveis novas enzimas.…”

Isolation of Native Soil Microorganisms with Potential for Breaking Down Biodegradable Plastic Mulch Films Used in Agriculture

“…When formulations of plastics are known and a source of the feedstock is available, powdered plastic can be suspended in agar-based media and degradation determined by visualization of clearing zones 13 . This method has been used previously to identify microorganisms that degrade polymers such as polyurethane 20 , poly-(butylene succinate-co-adipate) 21 , and poly(lactic acid) 22 . A similar method involves suspending pure powdered plastic in liquid medium where the plastic is the sole carbon source 20,23 .…”

“…This method has been used previously to identify microorganisms that degrade polymers such as polyurethane 20 , poly-(butylene succinate-co-adipate) 21 , and poly(lactic acid) 22 . A similar method involves suspending pure powdered plastic in liquid medium where the plastic is the sole carbon source 20,23 . While these methods have the advantage of a defined system, they poorly mimic in situ degradation of BDMs.…”