Optimization of Polyhydroxybutyrate Production by Bacteria Isolated from Solid Waste Transfer Station, Teku, Nepal

Abstract

Current universal usage of plastics is causing adverse environmental impacts, particularly in the fields of natural resources depletion, production emissions and end of life waste management. This has urged the scientific community to search for potential renewable and eco- friendly resources. Bioplastics are the best alternative to this issue as it degrades naturally in environment by microorganisms. Moreover, bioplastics are produced by microorganisms during nutrient deficient conditions.  

 In this study, three PHB positive bacteria were isolated from solid waste collected from solid waste Transfer station at Teku, Kathmandu, Nepal. Based on their PHB production, the best isolate was selected for optimization and identification. The effect of different time (24, 48 and 72 hours), pH (6.5, 7, 7.5, 8), temperature (25°C, 30°C, 37°C and 42°C), carbon ( glucose, dextrose, fructose, maltose and sucrose) and nitrogen ( ammonium sulphate, ammonium nitrate, urea and peptone) sources were studied for high PHB production. The optimized culture conditions for selected isolate in terms of pH, temperature and time were found to be in pH 7 at 37°C for 48 hours respectively. The optimized culture condition in presence of 2% dextrose and 0.5% urea enhanced the PHB production to 81%.  On the basis of the morphological and biochemical characterization the selected isolate was identified as Bacillus coagulans. The extracted PHB was characterized through FTIR and GC analysis.