Bioconversion of cellulose and hemicellulose in reed sawdust to xylo-oligosaccharides and L-lactic acid

Abstract

Much of the carbohydrate-rich reed sawdust (RS) produced from the reed pulping mills is burned or buried, causing a waste of resources. The aim of this work is to effectively bio-convert cellulose and hemicellulose of RS to L-lactic acid and xylo-oligosaccharide (XOS) after liquid hot water (LHW) pretreatment. The experiments were carried out via separation hydrolysis fermentation (SHF) and simultaneous saccharification fermentation (SSF) by optimizing the culture and fermentation conditions of a probiotics compound composed of a consortium of lactic acid bacteria. In the end, functional feed additives containing 69.33 wt% L-lactic acid and 26.82 wt% XOS can easily be obtained without additional handling by SSF configuration at 40 ℃ for 82 h with the initial fermentation pH 7.0. The conversion rate of glucose to L-lactic acid reached 72.33%. The bioconversion of available portion in RS into XOS and L-lactic acid paves a new way for high-value utilization of reed residue resources.