Contributions of citrate in redox potential maintenance and ATP production: metabolic pathways and their regulation in Lactobacillus panis PM1

摘要: Lactobacillus panis PM1 belongs to the group III heterofermentative lactobacilli and can utilize various NADH-reoxidizing routes (e.g., citrate, glycerol, oxygen) according environmental conditions. In this study, we investigated ability of L. produce succinate, acetate, lactate via citrate utilization. Possible pathways, as well regulation, for metabolism were examined on basis genome sequence data metabolic profiles PM1. The presence led up-regulation, at transcriptional level, genes encoding lyase, malate dehydrogenase, malic enzyme pathways by 10- 120-fold. regulator dha operon coding glycerol dehydratase repressed expression lyase gene (10-fold). Metabolite analyses indicated that enhancement stimulated succinate yield. Citrate contributed energy production providing a major alternate pathway NAD+ regeneration allowed acetyl phosphate yield acetate/ATP instead ethanol/NAD+. Additionally, branching from oxaloacetate pyruvate increased pool lactate, which was then used ATP during stationary phase. However, redirection NADH-to-citrate utilization resulted in stress caused end-products (i.e., acetate). This reduced up 50 % but did not cause significant changes level. Overall, beneficial growth route producing extra ATP.