Biosynthesis and characterization of polyhydroxyalkanoate (PHA) by Pseudomonas aeruginosa-Bacillus subtilis consortium

Polyhydroxyalkanoates (PHAs) proved to be a viable alternative for petroleum-derived polymers, due to their close mechanical and physical traits. However, PHA production is associated with many challenges like microbial and substrate type that directly affect the amount and overall quality of the polymer. Thus, the use of efficient microbial consortia can fill the research gap of low metabolic potential for complex substrate conversion by a single strain. Furthermore, plant oils (a) have larger carbon content per unit mass than sugars, (b) enter catabolism more rapidly through lipid β-oxidation, and (c) include saturated and unsaturated fatty acids that microbes can easily convert into PHA that may allow for improved PHA yield. In the current work, a bacterial consortium was constructed from Pseudomonas aeruginosa EO1 and Bacillus subtilis LO1. The consortium was cultivated in two-step batch fermentation to study the impact of different cultural conditions on the yield and quality of PHA. By optimizing the significant variables through one variable at a time, a 7.2 gL −1 of high PHA yield was obtained. Further, FTIR and GC-MS of produced polymers revealed the occurrence of prominent functional groups and the existence of blends or PHA copolymers respectively. Beyond that, PHA thermoplastic starch biocomposite film demonstrated excellent thermal and mechanical stability through TGA. To conclude, microbial consortia Pseudomonas aeruginosa EO1 and Bacillus subtilis LO1 was first reported bacterial consortium for PHA production and have been utilized to meet the urgent demands for future applications of sustainable polymers with desired characteristics. • Groundnut oil is a renewable and cost-effective carbon source for PHA production. • Bacterial consortium produced 7.2 gL −1 of PHA. • Optimized conditions were pH 7, temperature 35 °C, time-interval 72 h, inoculum 4 %, groundnut oil 2 %, and (NH 4 ) 2 SO 4 1.5 %. • Bacterial PHA were structurally characterized and confirmed as mcl-PHA using FT-IR and GC-MS techniques. • The study demonstrates bacterial consortium (EO1 +LO1) for sustainable mcl-PHA biopolymer production.