초록
<P><B>Abstract</B></P> <P>This study focused on the process development for the <SMALL>D</SMALL>-lactic acid production from cellulosic feedstocks using the <I>Lactobacillus plantarum</I> mutant, genetically modified to produce optically pure <SMALL>D</SMALL>-lactic acid from both glucose and xylose. The simultaneous saccharification and fermentation (SSF) using delignified hardwood pulp (5–15% loads) resulted in the lactic acid titers of 55.2–84.6g/L after 72h and increased productivities of 1.77–2.61g/L/h. To facilitate the enzymatic saccharification of high-load pulp at a fermentation temperature, short-term (⩽10min) pulverization of pulp was conducted, leading to a significantly improved saccharification with the suppressed formation of formic acid by-product. The short-term milling followed by SSF resulted in a lactic acid titer of 102.3g/L, an optical purity of 99.2%, and a yield of 0.879g/g-sugars without fed-batch process control. Therefore, the process presented here shows promise for the production of high-titer <SMALL>D</SMALL>-lactic acid using the <I>L. plantarum</I> mutant.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Process for high-titer <SMALL>D</SMALL>-lactic acid production from cellulosic feedstocks. </LI> <LI> Simultaneous saccharification and fermentation is suggested to improve the process. </LI> <LI> To improve saccharification of high-load pulp, high-impact pulverization is applied. </LI> <LI> A combined process for increasing the lactic acid titer above 100g/L. </LI> </UL> </P>