Dual-function strategy: simultaneous biopolymer production and lead biosorption by Bacillus paramycoides in single-batch fermentation process.

The conventional physicochemical processes of lead removal from contaminated wastewater are cost-intensive and generate toxic secondary wastes. Therefore, employing bacteria capable of lead biosorption will serve as a green, sustainable, safe and inexpensive process for lead removal, and its integration with polyhydroxyalkanoate (PHA) production will generate revenue. To integrate these two processes, Bacillus paramycoides isolated from the lake water were analyzed for lead biosorption and PHA production in mineral salt media containing lead nitrate at different incubation times. The bacterium showed a high lead biosorption of about 423 mg/g of biomass at 72 h of incubation, which was earlier not reported. Bacillus paramycoides produced polyhydroxybutyrate by utilizing sucrose in the media. The lead ions enhanced the PHA production up to 35.7% CDW in bacterial cells by inducing oxidative stress, and the ability of PHA polymer to adsorb lead ions prevented further oxidative damage to the cells. This study is the first report on using an integrated process approach for lead biosorption and PHA production in bacteria.