Valorization of wood waste for enhanced polyhydroxybutyrate production by Klebsiella sp. MK3

Abstract

Abstract The valorization of wood waste as a sustainable bacterial feedstock for the production of Polyhydroxybutyrate (PHB) is explored in this study, aiming to provide an environmentally friendly alternative to conventional plastics. Wood waste, treated with 4% sulfuric acid, served as the carbon source for isolating bacteria from Jalandhar waste streams, with the strain Klebsiella sp. MK3 identified as the most effective in PHB production after 16s rRNA sequencing. Analytical methods including the Molisch test, DNS, and sugar utilization tests confirmed sugar presence and consumption by the bacterial isolate. Media optimization using Design Expert 12.0 utilized a quadratic model, achieving a robust fit with an R² value of 98.6%. Optimization via Plackett-Burman design and response surface methodology enhanced PHB yield to 4.37 mg/mL, a significant increase over previous benchmarks. This yield was achieved under optimal conditions of 1.7% carbon concentration, 0.105% nitrogen concentration, and a constant temperature of 37 °C. Qualitative analysis of PHB by UV-Vis spectroscopy, FTIR, and NMR confirmed its purity and composition. The study highlights the potential of wood waste and wastewater as substrates for cost-effective PHB production, with significant applications in packaging, agriculture, medicine, and more, thus promoting reduced reliance on non-renewable resources and advancing sustainability goals.