Biodegradation of expanded polystyrene by bacterial isolates from selected dumpsites in Kaduna South, Nigeria

Abstract

Expanded polystyrene (EPS) is a petroleum-based plastic widely used in food packaging, insulation, and disposable products. Its resistance to natural degradation contributes significantly to environmental pollution and accumulation in terrestrial and aquatic ecosystems. This study investigated the biodegradation potential of bacterial isolates recovered from selected dumpsites in Kaduna South, Kaduna State, Nigeria. Soil samples were collected from domestic waste dumpsites, and bacterial isolates were recovered using standard microbiological techniques. The biodegradation potential of the isolates was evaluated using a weight-loss method over a 60-day incubation period. Isolates G, M, and P, which exhibited comparatively higher and consistent biodegradation efficiencies, were further characterized using biochemical tests and 16S rRNA gene sequencing. Biodegradation data were analyzed using repeated measures ANOVA at p < 0.05. Seventeen bacterial isolates were recovered and exhibited varying biodegradation efficiencies ranging from 6.59% to 61.52%. Isolate G, molecularly identified as Bacillus sp. strain GSKN, recorded the highest biodegradation efficiency (61.52%) after 60 days of incubation. Molecular characterization identified the remaining selected isolates as Bacillota bacterium strain MSKN and Pseudoxanthomonas sp. strain PSKN. The obtained nucleotide sequences were deposited in the NCBI GenBank database under accession numbers PZ345677, PZ345678, and PZ345679, respectively. The findings demonstrate that bacterial isolates from dumpsite soils can degrade EPS and highlight their potential for environmentally sustainable strategies to manage plastic-polluted environments.