The complete genome sequence of Lactobacillus bulgaricus reveals extensive and ongoing reductive evolution

M. Van De Guchte*, S. Penaud, C. Grimaldi, V. Barbe, K. Bryson, P. Nicolas, C. Robert, S. Oztas, S. Mangenot, A. Couloux, V. Loux, R. Dervyn, R. Bossy, A. Bolotin, J. M. Batto, T. Walunas, J. F. Gibrat, P. Bessières, J. Weissenbach, S. D. EhrlichE. Maguin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

312 Scopus citations

Abstract

Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) is a representative of the group of lactic acid-producing bacteria, mainly known for its worldwide application in yogurt production. The genome sequence of this bacterium has been determined and shows the signs of ongoing specialization, with a substantial number of pseudogenes and incomplete metabolic pathways and relatively few regulatory functions. Several unique features of the L. bulgaricus genome support the hypothesis that the genome is in a phase of rapid evolution. (i) Exceptionally high numbers of rRNA and tRNA genes with regard to genome size may indicate that the L. bulgaricus genome has known a recent phase of important size reduction, in agreement with the observed high frequency of gene inactivai ion and elimination; (ii) a much higher GC content at codon position 3 than expected on the basis of the overall GC content suggests that the composition of the genome is evolving toward a higher GC content; and (iii) the presence of a 47.5-kbp inverted repeat in the replication termination region, an extremely rare feature in bacterial genomes, may be interpreted as a transient stage in genome evolution. The results indicate the adaptation of L. bulgaricus from a plant-associated habitat to the stable protein and lactose-rich milk environment through the loss of superfluous functions and protocooperation with Streptococcus thermophilus.

Original languageEnglish (US)
Pages (from-to)9274-9279
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number24
DOIs
StatePublished - Jun 13 2006

Keywords

  • Adaptation
  • GC evolution
  • Large inverted repeat
  • Protocooperation
  • rRNA number

ASJC Scopus subject areas

  • General

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