Molecular Characterization, Optimization and Production of PHA by Indigenous Bacteria Using Alternative Nutrient Sources as Substrate

Abstract

Polyhydroxyalkanoates (PHA) are renewable, biodegradable biopolymer intracellularly accumulated by wide array of microorganisms as carbon reserve. This study investigates the influence of various cultural conditions on PHA production by a recently isolated local species under submerged fermentation. Six PHA producing strains were identified by 16S rDNA gene sequencing and strain Priestia flexa OWO1 showed satisfactory PHA productivity. The effects of production parameters were investigated and extraction of PHA was carried out using sodium hypochlorite method and maximum amount was detected after 72h. Maximum PHA production was obtained at incubation period of 48h, pH of 7.0 and temperature of 30oC. Amongst the hydrolysate of agro waste used, brewers spent grain (BSG) gave maximum yield of 3.01g/L while beans bran powder gave the highest PHA yields of 3.9 g/L amongst the organic nitrogen sources tested.  Analysis of the crude PHA by Fourier Transform Infrared Spectroscopy (FT-IR) showed the presence of methyl, methylene as well as carbonyl functional groups. PHA production was higher after optimizing the production conditions as compared to basal medium therefore the utilization of these cheap renewable resources as alternative substrates for production of PHA make the process cost effective and sustainable.