Efficient production of polymer-grade d-lactate by Sporolactobacillus laevolacticus DSM442 with agricultural waste cottonseed as the sole nitrogen source

In this study, we show that Sporolactobacillus laevolacticus DSM442 can produce d-lactate by using cottonseed as the sole nitrogen source. The cottonseed was enzymatically hydrolyzed and simultaneously utilized during d-lactate fermentation. Under optimal conditions, a high d-lactic acid concentration (144.4 g/L) was obtained in a fed-batch fermentation within 35 h, with an average productivity of 4.13 g/(L h) and a yield of 0.96 g/g glucose. The optical purity of d-lactic acid in the broth was 99.3%, which meets the requirement for use in lactic acid polymerization. Our study represents a cost-effective method for polymer-grade d-lactate production using cheap agricultural wastes.