Ignavibacterium album gen. nov., sp. nov., a moderately thermophilic anaerobic bacterium isolated from microbial mats at a terrestrial hot spring and proposal of Ignavibacteria classis nov., for a novel lineage at the periphery of green sulfur bacteria Iino, Takao and Mori, Koji and Uchino, Yoshihito and Nakagawa, Tatsunori and Harayama, Shigeaki and Suzuki, Ken-ichiro,, 60, 1376-1382 (2010), doi = https://doi.org/10.1099/ijs.0.012484-0, publicationName = Microbiology Society, issn = 1466-5026, abstract= A moderately thermophilic chemoheterotrophic bacterium, strain Mat9-16T, was isolated from microbial mats developed in hot spring water streams from Yumata, Nagano, Japan. Cells of strain Mat9-16T were strictly anaerobic, Gram-stain-negative, non-sporulating, non-motile and short to long rods (2.0–15.5 μm in length). Strain Mat9-16T grew fermentatively with optimum growth at 45 °C, pH 7.0–7.5 and 1 % NaCl (w/v). Phylogenetic analysis based on the 16S rRNA gene revealed that strain Mat9-16T was affiliated with an uncultivated lineage, and the nearest cultivated neighbours were green sulfur bacteria belonging to the class Chlorobea with 77–83 % sequence similarity. However, strain Mat9-16T could not grow phototrophically and did not possess light-harvesting structures, morphologically and genetically, such as the chlorosomes of green sulfur bacteria. On the basis of phenotypic features and phylogenetic position, a novel genus and species are proposed for strain Mat9-16T, to be named Ignavibacterium album gen. nov., sp. nov. (=NBRC 101810T =DSM 19864T). We also propose to place the cultivated bacterial lineage accommodating the sole representative Mat9-16T in a novel class, Ignavibacteria classis nov. In addition, we present a formal description of the phylum-level taxon ‘Chlorobi’ as Chlorobi phyl. nov., language=, type=