초록
<P><B>Abstract</B></P> <P>Whey is an important byproduct of the dairy industry containing mainly lactose and proteins. However, few studies have been conducted on co-utilization of lactose and proteins in whey for chemical production. To establish an efficient bioconversion method for the comprehensive utilization of cheese whey, a low-cost and labor-saving method for D-lactic acid production from cheese whey powder (CWP) was investigated and optimized in this study. CWP could be directly utilized by <I>Lactobacillus bulgaricus</I> CGMCC 1.6970 without the addition of extra nutrients. To fully utilize proteins in CWP, different proteases were selected to hydrolyze CWP, and the highest D-lactic acid concentration was obtained using neutral protease pretreated CPW as substrate. D-Lactic acid concentration could be further improved by adding a small amount of yeast extract. Based on the optimization, 70.70 g/L D-lactic acid with an average productivity of 1.47 g/L/h was obtained from batch fermentation. In fed-batch fermentation, a high D-lactic acid concentration (113.18 g/L) was obtained with an average productivity of 2.36 g/L/h. All the fermentations were carried out under an open condition without sterilization. This study presented a simple and economic strategy for CWP valorization and D-lactic acid production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Efficient D-lactic acid production from cheap cheese whey powder was demonstrated. </LI> <LI> Neutral protease was suitable for pretreatment. </LI> <LI> Lactose and proteins in cheese whey powder were co-utilized in fermentation. </LI> <LI> 113.18 g/L D-lactic acid with a productivity of 2.36 g/L/h was obtained. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>