Affiliation:
1. Department of Biochemistry and Molecular Biology, Dalhousie University, and Genome Atlantic, Halifax, Nova Scotia, Canada
Abstract
ABSTRACT
All cultivated isolates of the bacterial order
Thermotogales
are either thermophiles or hyperthermophiles, but
Thermotogales
16S rRNA gene sequences have been detected in many mesophilic anaerobic and microaerophilic environments, particularly within communities involved in the remediation of pollutants. Here we provide metagenomic evidence for the existence of
Thermotogales
lineages, which we informally call “mesotoga,” that are adapted to growth at lower temperatures. Two fosmid clones containing mesotoga DNA, originating from a low-temperature enrichment culture that degrades a polychlorinated biphenyl congener, were sequenced. Phylogenetic analysis clearly puts this bacterial lineage within the
Thermotogales
order, with the rRNA gene trees and 21 of 58 open reading frames strongly supporting this relationship. An analysis of protein sequence composition showed that mesotoga proteins are adapted to function at lower temperatures than are their identifiable homologs from thermophilic and hyperthermophilic members of the order
Thermotogales
, supporting the notion that this bacterium lives and grows optimally at lower temperatures. The phylogenetic analysis suggests that the mesotoga lineage from which our fosmids derive has used both the acquisition of genes from its neighbors and the modification of existing thermophilic sequences to adapt to a mesophilic lifestyle.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
52 articles.
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