Journal Article

Polyclonality of Concurrent Natural Populations of <i>Alteromonas macleodii</i>

Aitor Gonzaga, Ana-Belen Martin-Cuadrado, Mario López-Pérez, Carolina Megumi Mizuno, Inmaculada García-Heredia, Nikole E. Kimes, Purificación Lopez-García, David Moreira, David Ussery, Mila Zaballos, Rohit Ghai and Francisco Rodriguez-Valera

in Genome Biology and Evolution

Published on behalf of Society for Molecular Biology and Evolution

Volume 4, issue 12, pages 1360-1374
Published in print January 2012 |
Published online December 2012 | e-ISSN: 1759-6653 | DOI:

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  • Bioinformatics and Computational Biology
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We have analyzed a natural population of the marine bacterium, Alteromonas macleodii, from a single sample of seawater to evaluate the genomic diversity present. We performed full genome sequencing of four isolates and 161 metagenomic fosmid clones, all of which were assigned to A. macleodii by sequence similarity. Out of the four strain genomes, A. macleodii deep ecotype (AltDE1) represented a different genome, whereas AltDE2 and AltDE3 were identical to the previously described AltDE. Although the core genome (∼80%) had an average nucleotide identity of 98.51%, both AltDE and AltDE1 contained flexible genomic islands (fGIs), that is, genomic islands present in both genomes in the same genomic context but having different gene content. Some of the fGIs encode cell surface receptors known to be phage recognition targets, such as the O-chain of the lipopolysaccharide, whereas others have genes involved in physiological traits (e.g., nutrient transport, degradation, and metal resistance) denoting microniche specialization. The presence in metagenomic fosmids of genomic fragments differing from the sequenced strain genomes, together with the presence of new fGIs, indicates that there are at least two more A. macleodii clones present. The availability of three or more sequences overlapping the same genomic region also allowed us to estimate the frequency and distribution of recombination events among these different clones, indicating that these clustered near the genomic islands. The results indicate that this natural A. macleodii population has multiple clones with a potential for different phage susceptibility and exploitation of resources, within a seemingly unstructured habitat.

Keywords: Alteromonas macleodii; metagenome; population genomics; genomic island; constant-diversity; phage

Journal Article.  8862 words.  Illustrated.

Subjects: Bioinformatics and Computational Biology ; Evolutionary Biology ; Genetics and Genomics

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