(519a) Co-Culture in Submerged Hollow Fiber Membrane Bioreactor for Bioethanol Production On Glucose and Xylose

Lignocellulose is the most abundant renewable source of biomass available for conversion into bioethanol. In processing lignocellulosic biomass into bioethanol, major concerns are ethanol yield and fermentable sugars in the lignocellulosic hydrolysate. The major sugars in the hydrolysate are glucose and xylose. There is currently no wild-type microorganism that could efficiently accomplish the fermentation of this sugar mixture, so co-culture is a promising approach. However, the use of xylose-fermenting microorganism for co-culture in bioethanol production is limited due to their sensitivity to inhibitors, low ethanol tolerance and carefully regulated oxygen requirement. This project aims to develop a Submerged Hollow Fiber Membrane Bioreactor (SHFMB) with immobilized Zymomonas mobilis and Pichia stipitis for simultaneous co-fermentation of glucose and xylose in lignocellulosic hydrolysate. This SHFMB will facilitate efficient bioethanol production by shielding the cells from inhibitors present in lignocellulosic hydrolysate and from bioethanol inhibition in the fermentation broth. In addition, a proper regulating oxygen supply is applied to completely convert both sugars to ethanol with high yield.  Proof-of-concept is a major focus of this project, followed by optimization of the operating conditions.