Biodegradation of Ethylene Vinyl Acetate Using Klebsiella aerogenes EM011 Isolated from Effective Microorganisms

The amount of global plastic waste on land or in marine environments is a critical environmental issue. Plastic biodegradation by microorganisms, insect larvae, and enzymes has become one of the most popular solutions due to the ability of this strategy to generate environmentally benign byproducts, addressing ecological plastic waste concerns. This study revealed the biodegradation of ethylene vinyl acetate (EVA) by the bacterial strain identified as Klebsiella aerogenes EM011, isolated from effective microorganisms. The study found that K. aerogenes EM011 can survive in a carbon-free medium for 30 days using EVA films as the sole energy source, decomposing 0.65 ± 0.04% of 1 g of EVA film. The surface changes of the film were detected using scanning electron microscopy after treatment with K. aerogenes EM011. In addition, elemental modifications were detected in the imaged area of the plastic surfaces by energy-dispersive X-ray spectroscopy. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses were conducted to detect changes in the functional groups and chemical components, elucidating alterations on the surface of the EVA films. Through these physicochemical analyses, the formation of carbonyl groups (C=O), ester groups (C–O), and hydroxyl groups (–OH) confirmed the oxidation of EVA. Furthermore, the oxidation led to the decomposition of the EVA film, resulting in changes in its thermal stability and molecular weight distribution. These findings show that the K. aerogenes EM011 strain plays a role in accelerating the biodegradation of EVA.