Enhanced polyhydroxyalkanoates production: bacterial synergy transforms agricultural waste

Polyhydroxyalkanoates (PHA), produced by bacteria, emerging as a promising green biopolymer, offering a sustainable alternative to conventional plastics because of their prompt biodegradability and biocompatibility. A total of six PHA-producing bacterial strains were isolated and cultured individually and synergistically using glucose and agricultural waste (fruit peels). They were identified as Ochrobactrum sp., Pseudomonas putida, Bacillus halotolerans, Bacillus amyloliqueficians, Halomonas salina, and Pannonibacter phragmitetus. The strains produced the highest PHA percentage of 61.65% when cultured in monocultures using glucose and 46.12% with agricultural waste. When cultured synergistically, the PHA percentage came out to be 69% and 62% using glucose and agricultural waste, respectively. Transmission electron microscopic analysis confirmed their linear and centralized presence intracellularly. Fourier transfer infrared and nuclear magnetic resonance analyses confirmed the presence of carbonyl groups and the formation of the copolymer 3PHB-co-3PHV by mixed bacterial cultures utilizing agricultural waste. Furthermore, atomic force microscopy revealed a more uniform surface morphology produced from agricultural waste with maximum profile height as 21.37 nm as compared to glucose which is 71.23 nm. Enhancing PHA production through mixed bacterial cultures offers a promising and sustainable approach for converting agricultural waste into valuable biopolymers.