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

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