Acid soaking followed by steam flash-explosion pretreatment to enhance saccharification of rice husk for poly(3-hydroxybutyrate) production

Abstract

In order to exploit an abundant and cheap carbon source for poly(3-hydroxybutyrate) (PHB) production, the rice husk was pretreated with dilute sulfuric acid and steam flash-explosion to enhance the enzymatic saccharification. The yield of reducing sugars of pretreated rice husk hydrolysate came up to 266.5 mg/g rice husk, much higher than that of untreated rice husk hydrolysate (72.67 mg/g rice husk). This result indicated that the pretreatment can significantly enhance the yield of reducing sugars. Then the hydrolysate was used as a sole carbon source for PHB production by using Cupriavidus necator. Response surface method was used to optimize the fermentation conditions. Under optimum fermentation conditions (carbon source, 31.81 gL−1; nitrogen source, 1.8 gL−1; pH-value, 7.0; temperature, 27.1 °C), the PHB yield was 5.0 gL−1, which was in good agreement with the predicted value.