Degradation of plastic waste using stimulated and naturally occurring microbial strains

The capability of different strains derived from soil, activated sludge, farm sludge, and worms' excreta were investigated for biodegradation of high-density polyethylene, polystyrene foam, polypropylene and polyethylene terephthalate in unstimulated and stimulated conditions. Biodegradation using naturally occurring microbial strains examined in mixed (270 days) and individual (100 days) systems, while H2O2 stimulated strains were tested only in the mixed system (30 days). Penicillium raperi, Aspergillus flavus, Penicillium glaucoroseum and Pseudomonas sp. were isolated as the most plastic degrading microbes. Maximum weight loss was seen by incubation of polyethylene with Aspergillus flavus (5.5%) in unstimulated mix condition. Fourier Transform Infrared Spectroscopy (FT-IR) revealed formation of new functional groups as hydroxyl, carbonyl, alkene and alkoxy in the treated plastics. Visualisation of plastics by optical, atomic force (AFM) and electron microscopy (SEM) were also illustrated biodegradation. The derived by-products from microbial degradationwas tested, and found no inhibition on microbial growth and performance. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the biodegradation capability of microbial strains derived from soil, activated sludge, farm sludge, and worms' excreta on high-density polyethylene, polystyrene foam, polypropylene, and polyethylene terephthalate under unstimulated and stimulated conditions. The most effective plastic-degrading microbes were identified as Penicillium raperi, Aspergillus flavus, Penicillium glaucoroseum, and Pseudomonas sp. In the mixed condition, incubation of polyethylene with Aspergillus flavus showed the highest weight loss at 5.5%. Further analysis using Fourier Transform Infrared Spectroscopy revealed the formation of new functional groups on the treated plastics.