Project name: Lactococcus lactis subsp. lactis

Description: Lactococcus lactis is the main bacterium used for food fermentation and is a candidate for probiotic development. In addition to fermentation growth, supplementation with heme in aerobic conditions activates a cytochrome oxidase, which promotes respiration metabolism. In contrast to fermentation in which cells consume energy to produce mainly lactic acid, respiration metabolism dramatically changes energy metabolism, such that massive amounts of acetic acid and acetoin are produced at the expense of lactic acid. Our goal was to investigate the metabolic changes that correlate with significantly improved growth and survival during respiration growth. Using transcriptional time course analyses, mutational analyses, and promoter reporter fusions, we uncover two main pathways that can explain the robust growth and stability of respiration cultures: The acetate pathway contributes to biomass yield in respiration, without affecting medium pH. The acetoin pathway allows cells to cope with internal acidification, which directly affects cell density and survival in stationary phase. Our results suggest that manipulation of these pathways could lead to fine tuning respiration growth, with improved yield and stability.Overall design: Two samples are analyzed. The reference sample is at OD 2.5 (Cy3), and the two tests are at OD 5.6 and 6.4 (Cy5), respectively

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: Industrial

Last updated: 2014-04-14