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Published on: January 18, 2014
The complete genome sequence of Lactobacillus bulgaricus reveals extensive and ongoing reductive evolution
M van de Guchte1, S Penaud, C Grimaldi
1Génétique Microbienne and Mathématique, Informatique et Génome, Institut National de la Recherche Agronomique, 78352 Jouy en Josas Cedex, France. maarten.vandeguchte@jouy.inra.fr
Summary
Lactobacillus bulgaricus, crucial for yogurt, shows rapid genome evolution. Its genome features suggest adaptation to milk environments through gene loss and cooperation with Streptococcus thermophilus.
Area of Science:
- Microbiology
- Genomics
- Bacterial Evolution
Background:
- Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) is a key lactic acid bacterium widely used in yogurt production.
- Its genome sequencing reveals signs of specialization, including numerous pseudogenes and incomplete metabolic pathways.
Purpose of the Study:
- To investigate the unique genomic features of L. bulgaricus and understand its evolutionary trajectory.
- To explore the adaptive mechanisms driving L. bulgaricus from a plant-associated habitat to a milk environment.
Main Methods:
- Genome sequencing and comparative genomic analysis.
- Identification and analysis of unique genomic features such as gene content, GC content, and structural elements.
- Inference of evolutionary processes based on genomic data.
Main Results:
- The L. bulgaricus genome exhibits rapid evolution, evidenced by high rRNA/tRNA gene numbers, suggesting genome reduction.
- Elevated GC content at codon position 3 indicates a shift towards higher GC composition.
- A rare 47.5-kbp inverted repeat in the replication termination region points to a transient evolutionary stage.
Conclusions:
- L. bulgaricus is undergoing significant genome evolution, adapting to a milk environment.
- This adaptation involves the loss of non-essential functions and symbiotic relationships, specifically protocooperation with Streptococcus thermophilus.
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