Agricultural Microbes Genome 2 Conference

Poster: Microbial Genome Sequencing/Programs
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STUDY OF GENOMES OF DAIRY BACTERIA Lactococcus lactis

¹ Génétique Microbienne, INRA, Domaine de Vilvert, 78352 Jouy en Josas cedex, FRANCE

² Génoscope, Centre National De Séquençage, 2 rue Gaston Crémieux - BP 191 91006 Evry cedex, FRANCE

Lactococcus lactis is a bacterium living in nature on plants, animal skin and hairs. The dairy products are its artificial niches, created by industrial uses. The bacterium is the most common isolate from cheese starters. It is estimated that humans annually consume more than 10¹⁸ of these bacteria. To create a basis for genomic studies of L. lactis we sequenced entire genome of a laboratory strain IL1403 and performed collinear scaffolding of the chromosome of a genetic strain MG1363. These strains belong to two L. lactis strain clusters called lactis and cremoris, distinct by the spectra of standard dairy fermentation products. Genomic sequence revealed six prophages, 43 mobile elements and presence of competence genes, indicating importance of these in fast evolution of L. lactis. In connection with fermentation product distribution data, it also indicated a correlation between ability for homolactic fermentation and the presence of energetically advantageous transporting systems. A striking finding was the detection of a gene 95% identical to the one from E. coli and Salmonella, indicating a clear case of recent horizontal gene transfer between dairy gram positive and intestinal tract gram negative bacteria. Collinear scaffolding of the MG1363 genome, which shares 85% identity with that of IL1403, allows easy access to most of the genes from this strain.