Characterization of Melioribacter roseus gen. nov., sp. nov., a novel facultatively anaerobic thermophilic cellulolytic bacterium from the class Ignavibacteria, and a proposal of a novel bacterial phylum Ignavibacteriae. (9th January 2013)

• Record Type: Journal Article
• Authors: Podosokorskaya, Olga A.; Kadnikov, Vitaly V.; Gavrilov, Sergey N.; Mardanov, Andrey V.; Merkel, Alexander Y.; Karnachuk, Olga V.; Ravin, Nikolay V.; Bonch‐Osmolovskaya, Elizaveta A.; Kublanov, Ilya V.
• Is Part Of: Environmental microbiology. Volume 15:Number 6(2013:Jun.)
• Page Start: 1759
• Page End: 1771
• Publication Date: 2013-01-09
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12067
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>A novel moderately thermophilic, facultatively anaerobic chemoorganotrophic bacterium strain P3M‐2<sup>T</sup> was isolated from a microbial mat developing on the wooden surface of a chute under the flow of hot water (46°C) coming out of a 2775‐m‐deep oil exploration well (Tomsk region, Russia). Strain P3M‐2<sup>T</sup> is a moderate thermophile and facultative anaerobe growing on mono‐, di‐ or polysaccharides by aerobic respiration, fermentation or by reducing diverse electron acceptors [nitrite, Fe(III), As(V)]. Its closest cultivated relative (90.8% rRNA gene sequence identity) is <italic>Ignavibacterium album</italic>, the only chemoorganotrophic member of the phylum <italic>Chlorobi</italic>. New genus and species <italic>Melioribacter roseus</italic> are proposed for isolate P3M‐2<sup>T</sup>. Together with <italic>I. album</italic>, the new organism represents the class <italic>Ignavibacteria</italic> assigned to the phylum <italic>Chlorobi</italic>. The revealed group includes a variety of uncultured environmental clones, the 16S rRNA gene sequences of some of which have been previously attributed to the candidate division ZB1. Phylogenetic analysis of <italic>M. roseus</italic> and <italic>I. album</italic> based on their 23S rRNA and RecA sequences confirmed that these two organisms could represent an even deeper, phylum‐level lineage. Hence, we propose a new phylum <italic>Ignavibacteriae</italic> within the <italic>Bacteroidetes</italic>–<italic>Chlorobi</italic> group with a sole class <italic>Ignavibacteria</italic>, two families <italic>Ignavibacteriaceae</italic> and <italic>Melioribacteraceae</italic> and two species <italic>I. album</italic> and <italic>M. roseus</italic>. This proposal correlates with chemotaxonomic data and phenotypic differences of both organisms from other cultured representatives of <italic>Chlorobi</italic>. The most essential differences, supported by the analyses of complete genomes of both organisms, are motility, facultatively anaerobic and obligately organotrophic mode of life, the absence of chlorosomes and the apparent inability to grow phototrophically.</p> </abstract>