Physiological characterization of three lactic acid bacteria and their isogenic ldh deletion mutants shows that these organisms are optimized for Yatp and not ATP formation rates at their physiological pH

SysMO is a European transnational funding and research initiative on "Systems Biology of Microorganisms".

The goal pursued by SysMO was to record and describe the dynamic molecular processes going on in unicellular microorganisms in a comprehensive way and to present these processes in the form of computerized mathematical models.

Systems biology will raise biomedical and biotechnological research to a new quality level and contribute markedly to progress in understanding. Pooling European research ...

Comparative Systems Biology: Lactic Acid Bacteria

S. pyogenes M49 (591), E. faecalis V583, and L. lacis NZ9000 and their isogenic ldh deletion mutants were grown glucose free CDM-LAB medium in BIOLOG phenotype microarray plates PM01 and PM02. With this assay the abilitiy of the strains to grow on 190 different carbon sources was determined in 96 well format.

L. lactis, S. pyogenes and E. faecalis were grown in C-limited chemostat cultures at various pH's and dilution rates. General flux distribution, yields and other physiological factors were studied.

qATP values were calculated based on fermentation product formation and expected used biochemical pathways. These were averaged and used for calculation of the ATP required for maintenance and for growth. These data were subsequently used to calculate the qATP at the maximal growth rate by extrapolation

. L. lactis (NZ9000), E. faecalis (V538) and S. pyogenes (M49) wild type strain and their ldh- mutants were grown in batch cultures at 37°C in anaerobic 96 wells plates in either TH-broth supplemented with 0.5% (w/v) yeast (THY) or a chemically defined medium for LAB (pH 7.4) (CDM-LAB (10)). Both media were buffered with either 100 mM MES buffer or 100 mM MOPS buffer for growth at pH 6.5 and 7.5 respectively.

S. pyogenes was grown in C-limited cultures at pH 6.7 and 7.5 and at a growth rate of 0.05 and 0.15

E. faecalis was grown in C-limited cultures at pH 6.7 and 7.5 and at a growth rate of 0.05 and 0.15

L. lactis was grown in C-limited cultures at pH 6.7 and 7.5 and at a growth rate of 0.05, 0.15 and 0.40