Caldisericum exile gen. nov., sp. nov., an anaerobic, thermophilic, filamentous bacterium of a novel bacterial phylum, Caldiserica phyl. nov., originally called the candidate phylum OP5, and description of Caldisericaceae fam. nov., Caldisericales ord. nov. and Caldisericia classis nov. Mori, Koji and Yamaguchi, Kaoru and Sakiyama, Yayoi and Urabe, Tetsuro and Suzuki, Ken-ichiro,, 59, 2894-2898 (2009), doi = https://doi.org/10.1099/ijs.0.010033-0, publicationName = Microbiology Society, issn = 1466-5026, abstract= An anaerobic, thermophilic, thiosulfate-reducing bacterium, strain AZM16c01T, isolated from a hot spring in Japan [Mori, K., Sunamura, M., Yanagawa, K., Ishibashi, J., Miyoshi, Y., Iino, T., Suzuki, K. & Urabe, T. (2008). Appl Environ Microbiol 74, 6223–6229] was characterized in detail. The 16S rRNA gene sequence analysis had revealed that strain AZM16c01T was the first cultivated representative of the candidate phylum OP5. The cells were multicellular filaments with a single polar flagellum. The strain contained iso-C17 : 0 as the major fatty acid and menaquinone-8(H6), menaquinone-8(H8) and menaquinone-8(H10) as the respiratory quinones. The G+C content of the genomic DNA of strain AZM16c01T was 34.6 mol%. Optimum growth was obtained at 65 °C, pH 6.5 and in the absence of NaCl, with a doubling time of 10.6 h. On the basis of the results of phylogenetic analysis based on the 16S rRNA gene sequence and the characterization of the strain in this study, we propose the name Caldisericum exile gen. nov., sp. nov. for strain AZM16c01T (=NBRC 104410T=DSM 21853T). In addition, we propose the new phylum name Caldiserica phyl. nov. for the candidate phylum OP5 represented by C. exile gen. nov., sp. nov., and Caldisericaceae fam. nov., Caldisericales ord. nov. and Caldisericia classis nov., language=, type=