Synthesis and characterization of bioplastics, Polyhydroxyalkanoates produced from sugarcane bagasse by using Bacillus cereus

Abstract

Polyhydroxyalkanoates (PHA) are biodegradable bioplastics accumulated in microbial cells which have immense potential to replace the existing non-biodegradable plastics. This study focuses on optimizing Bacillus cereus growth conditions to enhance PHA formation, utilizing the sugarcane bagasse (SCB) as the primary feedstock. The SCB was subjected to enzymatic hydrolysis, resulting in 8.33 mg/g of total sugar production. Subsequently, Bacillus cereus was cultivated and the treated SCB was employed for PHA synthesis. An essential precursor to this synthesis involves an in-depth investigation into the characterization of the PHA produced using Bacillus cereus. A total of 20 experimental runs of different parameter conditions for Bacillus cereus culture to produce PHA were optimized by using the Response Surface Methodology (RSM). At an inoculum size of 8% (v/v), temperature of 25 °C, and incubation time of 48 h, the highest PHA was produced with 86.4 g/L or 62.1% (w/w). The optimal growth rate of Bacillus cereus was obtained at 7.71% (v/v), 35.1 °C for 48.3 h. The greatest PHA content and yield were found to be 57.9% (w/w) of PHA accumulation and 90.39 g/L, respectively. The synthesized PHA is characterized by using FTIR, XRD, FESEM-EDX, and soil burial test. From the analysis done, the properties of the produced sample were confirmed as the PHA. The soil burial test observed that the polymer was a PHA with a biodegradability rate of 41.73% in a week. The study successfully optimized the Bacillus cereus culture conditions for PHA production by using sugarcane bagasse hydrolysate at 8% (v/v) as the feedstock.