Role of Glucose and 2-Oxoglutarate/Malate Translocator (OMT1) in the Production of Phenyllactic Acid and p-Hydroxyphenyllactic Acid, Two Food-Borne Pathogen Inhibitors

This work aims to uncover how glucose affected the production of phenyllactic acid (PLA) and p-hydroxyphenyllactic acid (p-OH-PLA). The highest yields of PLA (68.53 mg/L) and p-OH-PLA (50.39 mg/L) were observed after Lactobacillus plantarum strain YM-4-3 fermentation in media containing 30 and 10 g/L glucose, respectively. Additionally, the antimicrobial activity of YM-4-3 against food-borne pathogens and the NADH/NAD(+) ratio were positively correlated with the production of PLA and p-OH-PLA, respectively. In addition, a 2-oxoglutarate/malate translocator coding gene (Omt1) was selected based on the qPCR results, and its knockout mutant, compared with the wild-type strain YM-4-3, showed that the PLA and p-OH-PLA production was decreased by 1.37-6.99 and 1.53-1.59 times, respectively. This result indicated that OMT1 was involved in the biosynthesis of PLA and p-OH-PLA. To conclude, this study suggests that glucose, NADH/NAD(+) ratio and/or the Omt1 gene, PLA, and p-OH-PLA production, and antimicrobial activity contribute to a cause-and-effect relationship.