Bacterial cell factories for sustainable production of green polyesters using saccharides: unlocking the potential to mitigate microplastic pollution

Microplastics, an upshot of petroleum-based synthetic polymers, have emerged as a global contaminant due to their persistence and accumulation in marine and terrestrial ecosystems. Polyhydroxybutyrate (PHB), a microbial-derived polyester, is an effective and sustainable alternative for synthetic polymers due to its pro-environmental qualities. In the present study, Bacillus subtilis FW1, isolated from a fish waste disposal site in Mokokchung, Nagaland, India, was able to accumulate 69.2% of PHB as cell dry weight of 2.31 gm/L and yielded a PHB concentration of 1.6 gm/L with a molecular weight 1.9 × 105 g/mol when 20% (w/v) monosaccharides especially glucose was used as the most favorable carbon substrate. The extracted PHB exhibited exceptional thermal stability. The melting temperature of the extracted PHB is 165 °C, whereas its maximum degradation temperature is 280 °C. Carbon (C) and oxygen (O) were found to be the main elemental compositions of the extracted PHB, according to XPS and FESEM-EDS studies. After 28 days of soil burial using the open windrow composting method, it was found that the PHB film had degraded by 59.6%. Evaluating the cytotoxicity of the extracted PHB in HepG2 cells revealed its non-cytotoxic nature. The results suggest that B. subtilis FW1 is a viable option for PHB biopolyester synthesis in the industrial setting. Furthermore, it may effectively combat the prevalent issue of microplastic pollution while gaining wide uses in the packaging, biomedical, agricultural, and other related sectors because of its biodegradability, biocompatibility, and eco-benign nature.