Production of High Optical Purity L-lactic Acid with Fiber Wastes from NaOH-AQ Pulping System

摘要

This study proposed a novel bioprocess utilization of fiber wastes from pulping process for the production of L-lactic acid.The bioprocess of Respective Saccharification Fermentation(RSF)and Simultaneous Saccharification and Fermentation(SSF)for L-lactic acid production by Bacillus coagulans using screened fiber wastes from a NaOH-AQ pulping system was investigated.The results showed the suitable conditions during RSF were:enzyme dosage 25IU/g,enzymatic hydrolysis time 72 h,enzymatic temperature 50°C,pH 4.8,inoculation size 10%,ferment time 48h,ferment temperature 37°C.Under these conditions,L-lactic acid content was up to 28.5 mg/ml and the purity was up to 96.4%.The optimum conditions during SSF were:enzyme dosage 30 IU/g,enzymatic temperature 50°C,pH 4.8,inoculation size 12%,ferment temperature 43°C,fermentation time 72h.Under these conditions,the reducing sugar was up to 25.6mg/ml,L-lactic acid content was up to33.5 mg/mL and the purity was up to 96.8%.