Physiological responses to folate overproduction in Lactobacillus plantarum WCFS1

Abstract

BackgroundUsing a functional genomics approach we addressed the impact of folate overproduction on metabolite formation and gene expression in Lactobacillus plantarum WCFS1. We focused specifically on the mechanism that reduces growth rates in folate-overproducing cells.ResultsMetabolite formation and gene expression were determined in a folate-overproducing- and wild-type strain. Differential metabolomics analysis of intracellular metabolite pools indicated that the pool sizes of 18 metabolites differed significantly between these strains. The gene expression profile was determined for both strains in pH-regulated chemostat culture and batch culture. Apart from the expected overexpression of the 6 genes of the folate gene cluster, no other genes were found to be differentially expressed both in continuous and batch cultures. The discrepancy between the low transcriptome and metabolome response and the 25% growth rate reduction of the folate overproducing strain was further investigated. Folate production per se could be ruled out as a contributing factor, since in the absence of folate production the growth rate of the overproducer was also reduced by 25%. The higher metabolic costs for DNA and RNA biosynthesis in the folate overproducing strain were also ruled out. However, it was demonstrated that folate-specific mRNAs and proteins constitute 8% and 4% of the total mRNA and protein pool, respectively.ConclusionFolate overproduction leads to very little change in metabolite levels or overall transcript profile, while at the same time the growth rate is reduced drastically. This shows that Lactobacillus plantarum WCFS1 is unable to respond to this growth rate reduction, most likely because the growth-related transcripts and proteins are diluted by the enormous amount of gratuitous folate-related transcripts and proteins.

B-Group vitamin production by lactic acid bacteria - current knowledge and potential applications

“…Although it is useful during technological applications to increase folate production, a recent study has been shown that folate overproduction in Lact. plantarum WCFS1 significantly reduced the growth rate of this micro‐organism (Wegkamp et al. 2010).…”

Transcriptome-Based Characterization of Interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in Lactose-Grown Chemostat Cocultures

“…Chemostat cultivation is highly valuable for this type of research, as it offers unique options for experimental design. In particular, chemostat cultivation enables researchers to manipulate individual cultivation parameters with minimal impact on other process conditions and at a fixed specific growth rate and, thereby, to dissect responses to individual environmental conditions (7)(8)(9)(10).…”

Systems solutions by lactic acid bacteria: from paradigms to practice

“…However, a recent comparative metabolomics and transcriptomics analysis of folate-overproducing Lactobacillus plantarum cells was reported to explain its reducing effect on the growth rate [99] . Remarkably, only little effect on the transcriptome and metabolome was observed but the great impact on the growth rate was explained by the gratuitous production of large amounts of folate-related transcripts and proteins.…”