Production of polyhydroxybutyrate (PHB) from soil bacterium (Bacillus megaterium TISTR 1814) with Cantaloupe waste extract as potential carbon source

Abstract

Background of the study: Polyhydroxybutyrate (PHB) is a natural biodegradable and biocompatible polymer having similar physical properties to those of standard conventional plastics. It is eco-friendly and can be produced economically at industrial scale via fermentation. Purpose of the study: In this present study, a gram positive soil bacterium, Bacillus megaterium TISTR 1814 was selected which accumulates polyhydroxybutyrate (PHB) as stored chemical energy. This is the first detailed study, on Cantaloupe waste extract as a cost effective nutrient source enriched with nitrogen sources for PHB yield were studied. Methods: B. megaterium TISTR 1814 was cultivated on designed media containing cantaloupe waste extract enriched with different nitrogen sources. The monosaccharides present in cantaloupe waste extract were analyzed by HPLC method. The biomass was weighed and PHB was extracted with sodium hypochlorite for FT-IR analysis. The disrupted cells were examined under scanning electron microscope to visualize PHB granules. Results: The highest cell density was observed at 30◦C after a period of 72 h of incubation of B. megaterium TISTR 1814 with highest biomass yield of 1.1 g/L using cantaloupe waste extract enriched with ammonium chloride as nitrogen source. On the other hand, maximum production of PHB was observed to be 0.46 g/g. dried biomass from 0.9 g/L dried biomass using Ammonium sulphate as inorganic nitrogen source. Conclusions: The Cantaloupe waste extract was found cost effective substrate for PHB production from B.megaterium strain. Incubation period after 72 h of incubation at 30◦C were the best conditions for PHB yield.