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

MARIELA CATONE* EQUALLY CONTRIBUTION; MARÍA MERCEDES PALOMINO*EQUALLY CONTRIBUTION; DANILO MARIO LEGISA; JOAQUINA FINA MARTIN; VICENTE MONEDERO GARCIA; SANDRA M RUZAL; MARIANA C ALLIEVI

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER

Lugar: Berlin; Año: 2021

0959-3993

Abstract In lactobacilli, CcpA is known to modulate the expression of genes involved in sugar metabolism, stress response and aerobic adaptation. This study aimed to evaluate a ccpA mutant of Lactobacillus casei BL23 to increase lactic acid production using cheese whey. The ccpA derivative (BL71) showed better growth rate and shorter generation time than the L. casei wild-type in the whey medium. In a stirred tank reactor, at 48 h, lactate production by BL71 was 8-fold 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 lag phase 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 of prtP expression confirmed this deregulation in BL71. Promoter analysis of the prtP gene revealed CcpA binding sites with high identity to the cre consensus sequence and the interaction of CcpA with this promoter was confirmed in vitro. Our results allow postulating that deregulation of the proteolytic system in BL71 allows a better exploitation of nitrogen resources in cheese whey, resulting in enhanced fermentation capacity. Therefore, the cppA gene could be a good target for future technological developments aimed at effective and inexpensive lactate production from dairy industrial wastes.Keywords: Lactic acid, Lactobacillus casei, CcpA, proteolytic system, cheese whey.