Utilization of sugarcane bagasse by-product for Polyhydroxyalkanoates production by Bacillus subtilis

Abstract

Sugarcane bagasse (SCB) is a by-product obtained from sugar processing that have abundance in Thailand. In order to manage this agricultural waste, it has been applied in numerous applications, especially fuel for power generation and producing value products. This study aimed to investigate the utilization of sugarcane bagasse for polyhydroxyalkanoates (PHAs) production by Bacillus subtilis TISTR 008. The SCB was treated with alkaline hydrogen peroxide before introducing hydrolysis process. The effect of sulfuric acid concentration and reaction time on hydrolysis were evaluated. The SCB hydrolysate obtained from 0.5% (v/v) for 120 min showed the highest reducing sugar concentration. A one factor at a time experiment was employed to optimize nitrogen sources leading to the highest PHAs concentration. The result found that B. subtilis TISTR 008 could accumulate the maximum PHAs when using urea as nitrogen source. A full factorial design was used to optimize the SCB hydrolysate concentration and fermentation time for PHAs improvement. The use of hydrolysate concentration and fermentation time at 30% v/v and 48 hours resulted in the maximum PHAs accumulation of 0.33 g/L and dry cell weight of 0.98 g/L. The chemical characteristics of the extracted PHAs were characterized by Fourier transform infrared (FT-IR) and Nuclear magnetic resonance (NMR). The spectral confirmed that the PHAs produced from B. subtilis TISTR 008 using SCB hydrolysate as substrate was PHB.