Plastic film biodegradation using Stutzerimonas stutzeri with metal nanoparticles as degradation enhancers-A...

Worldwide, one third of waste accumulation was shared by solid waste plastic bags which play a major role in manufacturing and packaging industries. Mismanage of waste plastics results in soil absorption and leads to soil infertility and structural degradation of soil. Biodegradation of plastic films enlighten the microbial activity towards plastic treatment without harming the ecosystem. Advancement towards biodegradation with aid of nanoparticles as degradation enhancer provides a synergistic approach to mitigate the plastic pollution. In this study, plastic degrading microorganisms were isolated from agriculture soil and metal nanoparticles such as Zinc oxide (ZnO) and Zinc-Magnesium oxide (ZnO-MgO) nanoparticles were synthesized using Co-precipitation method. Thus prepared inorganic metal nanoparticles were subsequently added to enhance the microbial degradation action. The synthesised nanoparticles appeared as hexagonal nanoflakes with a size range of 32.8 and 35 nm respectively. The isolated strain from the soil Stutzerimonas stutzeri, a gram negative bacterium was identified using 16S rRNA sequencing technique. The plastic films treated with isolated strain, showed 65% of degradation efficiency rate in the presence of synthesised nanoparticles as enhancers. SEM analysis confirmed the bacterial adhesion and revealed significant structural damage such as cracks, pits, holes and erosion in plastic film. FT-IR analysis revealed the presence of functional groups such as carbonyl (C=O) and (-CH) stretching at 1076 cm^-1 and 719 cm^-1 as a indication of polymer degradation. Further, simpler metabolic by-products formation such as fatty acids and succinic acid were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Further, metabolic byproducts were analyzed using gas chromatography-mass spectrometry (GC-MS) and their toxicity was assessed using the Allium cepa as an invitro plant model. The absence of negative effects on mitotic cell division suggested that no toxic compounds were released during the microbial degradation process. This study reveals about an improved method of nanoparticles assisted biodegradation which may pave a better pathway for sustainable solution in plastic waste management.