Bioprospecting Bacillus spp. from Waste Garbage-contaminated Soil for Sustainable PHA Production

Abstract

Background: The use of synthetic plastics and their products on a big scale causes waste disposal problems, leading to environmental pollution. Synthetic plastics derived from petroleum products like polyethylene, polypropylene, polyvinyl chloride, and polystyrene are all non-degradable and recalcitrant in the environment. The most studied and observed Polyhydroxyalkanoates (PHAs) are poly-3-hydroxybutyrate (PHB) stored in intracellular granules. Aim: To produce Polyhydroxyalkanoates (PHAs) from bacteria isolated from waste -garbage contaminated soil and confirm the production of PHAs by various techniques. Methodology: The production of PHA from the bacteria isolated from waste-garbage contaminated soil, especially collected in the Solapur district. Further isolates were characterized using morphological, cultural, biochemical, and molecular methods, including 16S rRNA gene sequencing, with phylogenetic analysis. The isolated and selected strain was studied for the extraction of PHAs and extended to evaluate the effect of various environmental parameters. Results: The isolates (PHB 1-5 ) were confirmed as PHA producers via Sudan Black B staining, and identified as members of the Bacillus cereus group, specifically Bacillus paramycoides (PHB-1, PHB-2) and Bacillus cereus (PHB-3). The confirmed and selected candidate of the PHB 5 strain is achieving a maximum PHA yield. Optimization shows that the PHB 5 thrives in alkaline conditions and prefers low salinity. FTIR analysis confirmed the biopolymer structure, showing characteristic peaks at 1723 cm⁻¹ (C=O ester carbonyl) and 1280–1106 cm⁻¹ (C–O–C stretching). Conclusion: These microorganisms demonstrate significant potential for efficient, high-volume production of biodegradable bioplastics.