Production of Polyhydroxyalkanoates through Soybean Hull and Waste Glycerol Valorization: Subsequent Alkaline Pretreatment and Enzymatic Hydrolysis

Alkaline pretreatment and sequential enzymatic hydrolysis of soybean hull were investigated to obtain fermentable sugars for polyhydroxyalkanoates production along with residual glycerol as low-cost carbon sources. Soybean is composed approximately 32% cellulose, 12% hemicellulose, 6% lignin, 11% protein. was carried out 2% NaOH concentration, 10% (w/v) biomass loading, 60 min incubation time in an autoclave at 120 °C. The response surface methodology (RSM) based on the central composite design (CCD) tool employed optimize process, where variables enzymes’ considered. maximum total reducing concentration obtained 115.9 g∙L−1 enzyme 11.5 mg protein/g dry substrate preparation B1, 2.88 XylA, 57.6 U/g β-glucosidase, after 42 h 45 °C, pH 4.5. Subsequently, saccharification step conducted by increasing processing scale, using a 1 L tank stirring controlled temperature. Implementing same concentrations 4.5, temperature 260 mL working volume, h, under fed-batch operation feeding 14 22 hydrolysate 185.7 obtained. Initially, verify influence different sources Cupriavidus necator DSMz 545 production, batch fermentations developed, testing laboratory-grade glucose, hydrolysate, waste (a by-product biodiesel available large quantities) one-factor-at-a-time assays, mixture glycerol. Then, consumed C. necator, producing 12.1 achieving 39% polyhydroxyalkanoate (PHB) accumulation. To best our knowledge, this first that has been used source produce polyhydroxyalkanoates, results suggest agro-industrial viable alternative feedstock value-added components.