Biodegradation of polyacrylic and polyester polyurethane coatings by enriched microbial communities

Abstract

Microbial communities are more effective in degrading natural polymers and xenobiotics than pure cultures. Biodegradation of polyacrylic and polyurethane polymers by bacterial and fungal strains has been addressed, but limited information about their biodegradation by microbial communities exists. The aim of this work was to evaluate the ability of three enriched microbial communities (BP1h, BP3h, and BP7h), selected from deteriorated foam pieces collected in a landfill, to biodegrade the polyacrylic component of the 2K-PU coating Bayhydrol® A2470 and the polyester polyurethane coating NeoRez™ R-9637. Two communities were further selected to quantify extracellular esterase, protease, and urease activities, to identify their taxonomic composition, and to analyze the ability of their isolated members to grow in those polymers. The growth of the three communities was larger in polyester polyurethane than in polyacrylic and their biodegradative activities affected ester, urethane, ether, aromatic, and aliphatic groups of the compounds present in the coatings. From all the communities growing in polyacrylic or in polyester polyurethane, two and five different types of colonies were isolated, respectively. In polyacrylic, extracellular esterase and protease activities were at their maximum level at 7 days of culture, whereas in polyester polyurethane, protease and urease were greatest at 21 days. All the isolated community members were identified as xenobiotics degraders. The complete communities grew better in media with the polymers than the isolated members. This is one of the few studies reporting biodegradation of synthetic polymers by microbial communities and serves as basis for developing synthetic consortia with enhanced degradative abilities.