Production of polyhydroxyalkanoate PHA using bacterial isolates from various polluted ecological niches using inexpensive carbon sources biowastes

Abstract

Polyhydroxyalkanoates (PHAs) are produced by many bacteria when exposed newlineto adverse/unfavorable conditions. As a very well-known fact, PHAs have the newlinepotential to replace the current non-biodegradable petrochemical-based plastics owing newlineto its properties of biodegradability, thermoprocessible materials and newlinebiocompatibility. The study concentrates on production of PHA from microbial newlineisolates selected after isolation from polluted landfill soil and effluent water, by newlineutilizing unique a carbon source. For comparison, a known PHA producer namely newlineCupriavidus necator was used. After serially diluting the two polluted sources (soil newlinefrom landfills and water from effluent treatment plant), many bacterial isolates were newlineobtained and out of which, fourteen morphologically different bacterial strains were newlineidentified and isolated. These isolates were further confirmed to be different by newlineperforming various biochemical tests. These eight bacterial isolates were further newlinestudied for their ability to utilize the inexpensive carbon sources and grown to newlineproduce biomass and simultaneously produce PHA using combinations of different newlineparameters, four inexpensive carbon sources (orange peel, banana peel, onion peel newlineand pomegranate peel) with different combinations of carbon: nitrogen (C:N) ratios newline(1:1, 2:1, 3:1 and 4:1) and four different time durations (24h, 48h, 72h and 96h). The newlineresults obtained were analyzed statistically by incorporating ANOVA, t-test and newlinelogistic regression method. The highly significant (plt0.005) amount of PHA newlineaccumulation obtained by reference strain Cupriavidus necator was 64% in orange newlinepeel, 80% in banana peel, 82% in onion peel and 71% in pomegranate peel. The best newlineresults obtained by bacterial isolates in orange peel was 82% (plt0.005) by Bacillus newlinevelezensis BTR 2015 in 1:1 24h, in banana peel was 85% (plt0.005) by Geobacillus newlinestearothermophilus TKR1707 in 4:1 96h, in onion peel was 85% (plt0.005) by newlineBacillus subtilis RVR2988 in 3:1 72h and in pomegranate peel was 83% (plt0.005) newlineby Bacillus halotolerans DSM8802 in 1