Highlights Hot water pretreatment of corn fiber resulted in a high polyhydroxybutyrate (PHB) yield (0.36 g PHB/g sugars). Alkaline pretreatment yielded less glucose and consequently produced less PHB compared to hot water pretreatment. Controlling hydrolysate pH with phosphate buffer during fermentation improved PHB production. The use of acetate buffer during enzymatic hydrolysis led to the highest PHB yield. ABSTRACT. The urgent need to replace petrochemical-based plastics with bioplastics like polyhydroxybutyrate (PHB) has increased over the last few decades. The major restraint in the process is the high substrate cost. The conversion of a cost-effective carbon source from lignocellulosic biomass to PHB could solve that problem and make biorefineries more economical. In this study, a cheap carbon source, corn fiber (CF), was used to produce PHB. Corn fiber hydrolysate was produced by pretreating CF followed by enzymatic hydrolysis. Glucose and xylose are the main sugars present in corn fiber hydrolysate. Paraburkholderia sacchari DSM 17165 is a well-known PHB-producing organism that can ferment these monomeric sugars to PHB. Pretreatment methods, the buffer used during enzymatic hydrolysis, and pH during batch fermentation have a substantial effect on PHB yield. This study explored the effect of two pretreatment strategies, liquid hot water (LHW) pretreatment and alkaline pretreatment, and several pH control strategies on PHB yields. The highest PHB yield of 0.36 g PHB/g sugars was obtained with LHW pretreatment, acetate buffer in enzymatic hydrolysis, and using phosphate buffer as pH control during fermentation as compared to the PHB yield of 0.36 g PHB/g sugars in control. Keywords: Biodegradable, Bioplastic, Corn fiber.
Mitra et al. (Thu,) studied this question.