Identification of esterase inAspergillus flavusduring degradation of polyester polyurethane1

Polyurethane not only has applications including tires and insulation, but also is an essential element of our lives. Based on previous reports, some strains of fungus including Pestalotiopsis microspora have been reported to degrade this plastic. The ultimate objective is to create a genetically engineered variant of Pichia pastoris which will digest polyester polyurethane (PUR) using the enzyme responsible for PUR degradation from Aspergillus flavus ; this year we aim to identify the esterase, believed to be responsible for the biodegradation. The degradation of TPU (a granular form of thermoplastic PUR) and water-based PUR by A. flavus , was tested using incubation with shaking for one month. Although no significant weight loss was observed, the fungus was capable of growing on the water-based PUR as a food source. Esterase, the enzyme responsible for the degradation of the water-based PUR, was observed in the water-based PUR lane of the Native PAGE gel and has a molecular weight of approximately 20 kDa. Since the only difference between the experimental water-based lane and experimental TPU lane, was the esterase band, it can be confirmed that the degradation of the plastic and growth of fungus can be attributed to the esterase. Le polyurethane a non seulement des applications dans la fabrication des pneus et pour l’isolation, mais est aussi un element essentiel a notre vie. Conformement a des rapports antecedents, certaines souches de mycete, dont Pestalotiopsis microspora , ont su demontrer la degradation du plastique. L’objectif ultime est la creation d’un mutant du Pichia pastoris par genie genetique qui pourra digerer le polyester polyethane (PUR) en utilisant l’enzyme responsable de la degradation du PUR de l’Apergillus flavus ; cette annee, nous visons a identifier l’esterase, soupconnee d’etre responsable de la biodegradation. La degradation du TPU (une forme granulaire du PUR thermoplastique) et du PUR a base d’eau par A. flavus furent testees par incubation avec agitation pendant une duree d’un mois. Malgre aucune perte de poids significative observee, le mycete fut capable de croitre sur les PUR a base d’eau comme source alimentaire. L’esterase, l’enzyme responsible de la degradation des PUR a base d’eau, fut observe dans  le puits avec du PUR a base d’eau du gel PAGE (electrophorese sur gel polyacrylamide) Native et a une masse moleculaire d’environ 20kDa. Etant donne que la seule difference entre le puits experimental a base d’eau et le puits experimental TPU etait la bande d’esterase, on peut confirmer que la degradation du plastique et la croissance du mycete peuvent etre attribuees a l’esterase.