SysMO-LAB2 aims to extend and further develop comparative systems biology approaches to understand similarities and differences in fermentation behaviour of four Lactic Acid Bacteria (LAB). Lactococcus lactis, used in dairy food applications; Enterococcus faecalis, a major (fecal) contaminant in food and water as well as a contributor to food fermentation, and Streptococcus pyogenes, an important human pathogen, will continue to be studied. The fourth organism, Lactobacillus plantarum provides an importa nt extension to the LABs in SysMO-LAB1 and has been chosen as a wellcharacterized representative of the lactobacilli, an industrially important group of LAB. L. plantarum is associated with human health (probiotic) and is a versatile LAB found in very man y different niches. From our results in SysMO-LAB1, we concluded that our comparative analysis should be extended to be able to fully understand the phenotypic differences observed. This relates to effects of amino acid metabolism and the ability to expli citly model changes in enzyme levels. Moreover, we want to make use of the increasing number of sequenced strains of the same species, and use our models to explain the enormous diversity in acidification rates in such strains. This specific application o f comparative systems biology is of tremendous importance to the biotech industry and medicine, and
will blend comparative systems biology with comparative genomics, while harvesting on the opportunities provided by latest developments in sequence technol ogy.