Biodegradation of ethylene vinyl acetate using Klebsiella aerogenes isolated from Effective Microorganisms

Abstract

Abstract The amount of global plastic waste on land or in the marine environment is a critical environmental issue. Plastic biodegradation by microorganisms, wax worms, and enzymes has become one of the most popular solutions because it produces no harmful environmental derivatives for ecological plastic waste. This study revealed the biodegradation pathway of ethylene vinyl acetate by the bacteria strain Klebsiella aerogenes EM011, which was isolated from effective microorganisms. We identified that K. aerogenes can survive in a carbon-free environment, using ethylene vinyl acetate films as the sole source of energy and decomposing ethylene vinyl acetate microparticles. Next, we examined the degradation of the plastic surface after bacterial treatment using scanning electron microscopy. We detected the modifications in the imaged area of the plastic by energy-dispersive x-ray spectroscopy. Based on the imaging analysis, we conducted Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses to detect changes in functional groups and chemical components, elucidating alterations on the surface of the treated plastics. Through these physicochemical analyses, the formation of carbonyl groups (C = O), ester groups (C-O), and hydroxyl groups (-OH) confirmed the degradation of EVA plastic. Furthermore, oxidation led to the decomposition of the ethylene vinyl acetate film, resulting in changes to the plastic characteristics. These alterations were validated by thermal gravimetric analysis and Gel Permeation Chromatography. These findings show that the K. aerogenes EM011 strain has a role in accelerating the biodegradation of ethylene vinyl acetate plastic.