Microorganisms participating in the biodegradation of modified polyethylene films in different soils under laboratory conditions

The degree of biodegradation of low-density polyethylene (LDPE) films modified with Bionolle (R) polyester in different soils under laboratory conditions was evaluated. Films were incubated in soils from waste coal, a forest and an extinct volcano crater. Prior to degradation studies, soils underwent chemical and microbiological analysis. Film weight loss and mechanical properties, as well as the surface of the polymeric samples determined via scanning electron microscopy, were evaluated after 75, 150 and 225 days of biodegradation. Important chemical changes in the polymeric chains were detected by Fourier Transform Infrared Spectroscopy (FTIR). Fungal and bacterial species that were able to grow on the film surfaces were monitored in order to see whether the films were easily colonised by autochthonous microorganisms (i.e., typical to each soil). Identification of microorganisms was based on their cellular fatty acid methyl ester (FAME) profiles. Biodegradation of modified polyethylene films in soils led to significant changes (i.e., elongation at brake of 98%) in their mechanical properties that were caused by biochemical modifications of both polyester and polyethylene. Compared to waste coal soil, films underwent rapid biodegradation in soils that were rich in organic matter. Bacteria belonging to the genus, Bacillus, and the fungi, Gliocladium viride, Aspergillus awamori and Mortierella subtilissima, were easily able to colonise both polyethylene and polyethylene modified with Bionolle (R). (C) 2011 Elsevier Ltd. All rights reserved.