Production of Polyhydroxybutyrate from Crude Glycerol and Spent Coffee Grounds Extract by Bacillus cereus Isolated from Sewage Treatment Plant

Abstract

Production of biodegradable polymer polyhydroxyalkanoates(PHAs) from industrial wastes exhibits severaladvantages such as recycle of waste and the production ofhigh valuable products. To this end, this study aimed at isolatingfrom the sewage treatment plant a PHA producing bacteriumcapable of utilizing wastes generated from biodiesel andfood industries. A Bacillus cereus strain capable of producingpoly(3-hydroxybutyrate) [P(3HB)] was isolated, which wasfollowed by confirmation of P(3HB) accumulation by gaschromatographicanalyses. Then, the effects of nutrient limitationon P(3HB) production by B. cereus was first examined. Cells cultured in a minimal medium under the limitation of nitrogen,potassium and sulfur suggested that nitrogen limitationallows the highest P(3HB) accumulation. Next, production ofP(3HB) was examined from both waste of biodiesel production(crude glycerol) and waste from food industry (spent coffeegrounds). Cells cultured in nitrogen-limited minimalmedium supplemented crude glycerol and waste spent coffeegrounds extract accumulated P(3HB) to the contents of 2.4%and 1.0% of DCW. This is the first report demonstrating thecapability of B. cereus to produce P(3HB) from waste rawmaterials such as crude glycerol and spent coffee grounds.