Microbial Degradation of Polyester Microfibers Using Indigenously Isolated Bacterial Strain Exiguobacterium Sp.

Abstract

Synthetic microfibers are emerging environmental microplastic pollutants released from different industrial and domestic sources. The present investigation describes the isolation of potential bacterial strains from microplastic-contaminated sites of Bhubaneswar city of Odisha, India. Four morphologically distinct bacterial strains were isolated using 2% polyethylene glycol (PEG) supplemented nutrient agar (NA) medium and were screened for their polymer tolerance ability by growing them on 2%–8% PEG. A single microorganism capable of growing on 8% PEG was selected for biodegradation experiment. Through 16S rRNA sequencing, the selected bacterial strain was identified as Exiguobacterium sp. with gene bank accession number ON318396. The microbial strain's microfiber biodegradation ability was assessed in a laboratory setting over a period of 28 ± 2 days, utilizing optimized conditions with an initial pH of 7, 2 mL inoculum volume, an incubation temperature of 30°C ± 2°C, and 150 rpm, using 2 g of polyester microfiber. In optimum conditions, the weight loss of the treated sample with the selected microbial strain was 19.2%. The polyester degradation was confirmed through scanning electron microscopic images viewing the degradation of the polyester microfiber surfaces. Variation in functional groups confirmed through Fourier transform infrared spectrophotometry. Detection of carbonyl (C═O) group stretching band at 1711 cm⁻¹ through ATR-FTIR analysis in the treated sample confirmed the polymer biodegradation. The potential isolate can efficiently degrade polyester and, in the future, can be employed as a promising solution for the sustainable treatment of synthetic microfiber pollution.