Microbial Destruction of Polypropylene and Polyvinylchloride Samples under the Anaerobic Conditions

Abstract

Abstract—The most advantageous characteristic of the materials made of synthetic polymers, such as their resistance to biodegradation, is simultaneously the reason for their accumulation and environmental pollution. Nevertheless, some type of plastics under aerobic conditions undergo slow microbial degradation, however, there is lack of information on the anaerobic degradation of plastics. In this work, we studied the growth of anaerobic moderately thermophilic (55°C) consortiums in the presence of samples made of polypropylene (PP) and polyvinyl chloride (PVC). It was shown that the microbial biomass increased compared to the control, as well as anaerobic decomposition products (CO2, H2, and H2S) were detected, and the total weight of the plastics decreased by 4.4% (PP) and 6.5% (PVC) compared to the control. Bacterial cells adhere and form colonies and biofilms on the surface of the plastic materials. An analysis of the composition of microbial communities showed an increased number of anaerobic hydrolytics of the genus Tepidimicrobium, potential syntrophic bacteria of the genus Tepidanaerobacter, and especially sulfate-reducing bacteria (Desulfohalotomaculum). With help of differential scanning calorimetry and Fourier spectroscopy it was revealed that the decrease in the mass of plastic mainly occurred due to the hydrolysis of additives (plasticizers). The role of such microbial communities in the aquatic environment and anaerobic layers of the municipal solid waste landfills, where PP and PVC plastics can be destructed under the elevated temperatures of anaerobic conditions, is discussed.