Miho Watanabe, Hisaya Kojima and Manabu Fukui.
International Journal of Systematic and Evolutionary Microbiology 63: 3574-3578.2013.

　山梨県みずがき湖から、Desulfotomaculum 属の新種となる細菌SR45株を分離・培養し、その系統的・生理生化学的特徴づけを行いました。SR45株は胞子形成性の硫酸還元細菌です。16S rRNA遺伝子塩基配列やGyrBアミノ酸配列に基づく系統解析の結果よりFirmicutes門Clostridia綱のPeptococcaceae科に分類されることが明らかになりました。特筆すべき点としては、この細菌は異なる13の16S rRNA遺伝子塩基配列のコピーを有していると考えられることです。細菌の中には16S rRNA遺伝子塩基配列を複数持つものもいますが、その中でもSR45株は配列の多さ、配列間のバリエーションの高さが特徴的であり、今後も研究を発展させて行きたいと考えています。

<Abstract>

A novel spore-forming, sulfate-reducing bacterium, strain SR45^T, was isolated from sediment of a freshwater lake, Lake Mizugaki, in Japan. Cells of strain SR45^T were rod-shaped (1.0–1.5×2.0–5.0 mm) and weakly motile; Gram staining and the KOH lysis test were negative. For growth, the optimum pH was 6.4–6.8 and the optimum temperature was 42–45℃. Strain SR45^T used sulfate, thiosulfate, sulfite and elemental sulfur as electron acceptors but not Fe (III). The G + C content of the genomic DNA was 41.1 mol%. Phylogenetic analyses based on genes for the 16S rRNA and DNA gyrase (gyrB) revealed that the isolated strain belonged to the family Peptococcaceae in the class Clostridia. The closest relative is Desulfotomaculum acetoxidans 5575^T, with 16S rRNA gene sequence similarity of 92–94 %. It is suggested that the strain is the second isolated member of Desulfotomaculum subcluster Ie. The isolate had multiple 16S rRNA gene copies, with 13 different sequences. On the basis of phylogenetic and phenotypic characterization, the name Desulfotomaculum intricatum sp. nov. is proposed, with the type strain SR45^T (= NBRC 109411^T = DSM 26801^T).