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Adaptation at the Extremes of Life: Experimental Evolution with the Extremophile Archaeon Sulfolobus acidocaldarius
Published on: June 14, 2024
Phase variation and genomic architecture changes in Azospirillum
Ludovic Vial1, Céline Lavire, Patrick Mavingui
1UMR CNRS 5557 Ecologie Microbienne, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.
Journal of Bacteriology
|July 21, 2006
Summary
Genomic rearrangements, including the loss or gain of large DNA replicons, drive phase variation in Azospirillum bacteria. These large-scale genomic changes are linked to the emergence of stable bacterial variants.
Area of Science:
- Microbiology
- Bacteriology
- Genomics
Background:
- Azospirillum lipoferum 4B produces a stable, nonswimming phase variant (4V(I)) with altered dye absorption.
- Phase variation in bacteria involves pleiotropic modifications, but the underlying molecular mechanisms remain unclear.
Purpose of the Study:
- To investigate whether genomic rearrangements occur during the phase variation of Azospirillum lipoferum strain 4B.
- To determine the role of large-scale genomic alterations in bacterial phase variation across different Azospirillum species.
Main Methods:
- Random Amplified Polymorphic DNA (RAPD) analysis to detect genomic differences between wild-type and variant strains.
- Cloning of RAPD fragments and hybridization to identify specific genomic regions.
- Pulse-field gel electrophoresis (PFGE) to analyze large replicons and assess genomic rearrangements.
Main Results:
- RAPD profiles differed between Azospirillum lipoferum 4B and its variant 4V(I), indicating genomic changes.
- A 750-kb replicon present in the wild type was absent in the 4V(I) variant, suggesting its loss during phase variation.
- Similar large-scale genomic rearrangements were observed in Azospirillum brasilense and Azospirillum irakense during phase variation.
Conclusions:
- Large-scale genomic rearrangements, such as the deletion or acquisition of replicons, are associated with phase variation in Azospirillum species.
- These genomic alterations contribute to the generation of stable bacterial variants with distinct phenotypes.
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