Studies on the biodegradation of natural and synthetic polyethylene by Pseudomonas spp

Abstract

The current article makes a comparative analysis between the biodegradation of natural and synthetic polyethylene by three different species of Pseudomonas. The three Pseudomonas spp. (P1, P2, and P3) were indigenous to locations: (1) domestic waste disposal site dumped with household garbage and vegetable waste; (2) soil from textile effluents drainage site; and (3) soil dumped with sewage sludge, respectively. The ability of these species in degrading natural and synthetic polyethylene was investigated. Pure culture shake-flask incubation for 8 weeks was performed for the purpose of biodegradation. The natural or biodegradable polyethylene used in the study was disposable plastic bags containing 6% vegetable starch. The initial and final dry weights of plastic bags before and after incubation in the culture medium were compared and the percentage of degradation was calculated. Among all the treatments, Pseudomonas sp. from sewage sludge dump (P1) was found to degrade polyethylene efficiently with 46.2% for natural and 29.1% for synthetic polyethylene. In contrast, Pseudomonas sp. from household garbage dump (P2) gave the lowest biodegradability of 31.4% and 16.3% for natural and synthetic polyethylene, respectively. However, Pseudomonas sp. isolated from textile effluents drainage site gave an intermediate biodegradability of 39.7% and 19.6% for natural and synthetic polyethylene, respectively. Overall, natural polyethylene gave a rapid biodegradation within the same duration than the synthetic ones. The active enzymes produced by the bacteria caused mechanical denting and weight loss in polyethylene.