Bioconversion of Groundnut Oil into Polyhydroxyalkanoate (PHA) by Bacillus Subtilis LO1

Polyhydroxyalkanoates (PHAs) are synthesized by microorganisms as cytoplasmic biopolymers in response to nutritional starvation. These biopolymers have diverse applications because of their non-toxic and biodegradable nature and can be an effective alternative to conventional petrochemical polymers as they offer similar qualities. For this purpose, PHA-producing bacterium LO1 was isolated from lubricating oil contaminated soil and identified as Bacillus subtilis (MK071733). Furthermore, LO1 was found to be the most prominent PHA accumulating strain on groundnut oil as carbon source under optimized growth conditions. The optimum growth conditions for PHA synthesis was pH 7, temperature 35 °C, incubation period 72 h, inoculum size 4%, (v/v), groundnut oil 2%, (v/v), and ammonium sulfate 1.5%, (w/v) in mineral salt medium (MSM). Under these optimized conditions, 5.52 g/L of PHA cell dry weight (CDW) was obtained from 9.8 g/L of bacterial dry cell weight (DCW) through two-stage shake flask cultivation. Further, extracted PHA was characterized via Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectrometry (GC-MS). These techniques confirmed the presence of mcl-PHA copolymers in the extracted polymer.