Lactic acid production using cheese whey based medium in a stirred tank reactor by a ccpA mutant of Lacticaseibacillus casei

This study aimed to evaluate accpA mutant ofLacticaseibacillus casei BL23 to increase lactic acid production using cheese whey. TheccpA derivative (BL71) showed better growth than theL. casei wild-type in the whey medium. In a stirred tank reactor, at 48  h, lactate production by BL71 was eightfold higher than that by BL23. In batch fermentations, the final values reached were 44.23 g L−1 for BL71 and 27.58  g L−1 for BL23. Due to a decrease in the delay of lactate production in the mutant, lactate productivity increased from 0.17  g (L.h)−1 with BL23 to 0.80  g (L.h)−1 with BL71. We found that CcpA would play additional roles in nitrogen metabolism by the regulation of the proteolytic system. BL71 displayed higher activity of the PepX, PepQ and PrtP enzymes than BL23. Analysis ofprtP expression confirmed this deregulation in BL71. Promoter analysis of theprtP gene revealed CcpA binding sites with high identity to thecre consensus sequence and the interaction of CcpA with this promoter was confirmed in vitro. We postulate that deregulation of the proteolytic system in BL71 allows a better exploitation of nitrogen resources in cheese whey, resulting in enhanced fermentation capacity. Therefore, theccpA gene could be a good target for future technological developments aimed at effective and inexpensive lactate production from dairy industrial wastes.Graphic abstract
Source: World Journal of Microbiology and Biotechnology - Category: Microbiology Source Type: research