Microbial degradation of plastic : comparison of synthetic and natural communities

Abstract

The processes of plastic biodegradation take into account a wide field of study involving several multidisciplinary approaches. The aim of this present work is to investigate plastic degradation from two ways. The first one is the study of the impact of diets on the intestinal microbiota of Galleria mellonella caterpillar, known to assimilate polyethylene. To this end, a denaturing gradient gel electrophoresis (DGGE) was performed, highlighting specie diversity variation but a constant specie richness. Moreover, identification of cultivable bacteria from the gut of G. mellonella larvae displays interesting species able to degrade polymer. The second approach is the study of the adhesion of biofilms on polyethylene surface, which is the first step of plastic biodegradation. For this purpose, XDLVO theory was explored through Zeta potential (ZP) measurement and contact angle measurement on microbial co-culture composed of Bacillus amyloliquefaciens and Trichoderma harzianum. The obtained ZP variation exhibits the complexity and heterogeneity of biofilms through time and space. These physicochemical analyses were performed on plastic surface supporting biofilms. Small variations were exhibited compared to the controls. This observation can be the consequence of a chemical modification of plastic surface caused by the microbial degradation and leading to a better adhesion of biofilm.