Bacterial Cellulose Production by Acetobacter xylinum CGMCC 1.2378 Using Coconut Shell Acid Hydrolysate as Carbon Source

Abstract

Bacterial cellulose (BC) was synthesized by Acetobacter xylinum using a carbon source of coconut shell hydrolysate, which was treated with an ultra-low concentration of sulfuric acid. The coconut shell was found to contain 57.13% holocellulose and 27.42% lignin. The effect of sulfuric acid concentration, reaction temperature, and reaction time on hydrolysis of coconut shell were evaluated by response surface methodology. The reducing sugar concentration was 8.39 g/L under the predicted optimum treatment at 200 °C for 32 min with a solution of 0.07% sulfuric acid. The holocellulose conversion rate was 56.1% at this condition. In a detoxification process using calcium hydroxide and activated carbon, furfural and hydroxymethylfurfural in the hydrolysate were almost completely removed, whereas formic acid and acetic acid levels decreased by 30%. After cultivation for 7 days at the reducing sugar status of 5 g/L, the BC production in medium with the detoxified hydrolysate could reach 1.66 g/L. After fermentation for 21 days, BC yield in medium using composited carbon source (20 g/L) of glucose and hydrolysate was 5.30 g/L. Structural analysis showed that BC obtained from medium of control and detoxified hydrolysate exhibited similar properties. This work provided a potential method for BC production.