Department of Informatics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.
Central Region Agricultural Research Center, National Agriculture and Food Research Organization, Nasushiobara, Tochigi 329-2793, Japan.
Int J Syst Evol Microbiol. 2020 May;70(5):3111-3116. doi: 10.1099/ijsem.0.004138. Epub 2020 Apr 6.
Two Gram-stain-positive, rod-shaped, non-motile, non-spore-forming, catalase-negative bacteria, designated strains SG162 and NK01, were isolated from Japanese rice grain silage and total mixed ration silage, respectively. They were initially identified as based on the 16S rRNA gene sequence similarities. However, the two strains were separated into a distinct clade from DSM 20057 (=JCM 1115) through whole-genome sequence-based characterization, forming an infraspecific subgroup together with strains CD034 and S42, whose genomic sequences were available in the public sequence database. Strains within the subgroup shared 99.4-99.7 % average nucleotide identity (ANI) and 97.5-99.0 % digital DNA-DNA hybridization (dDDH) with each other, albeit 96.9-97.0 % ANI and 76.0-76.6 % dDDH against DSM 20057. Strains SG162 and NK01 could utilize more substrates as sole carbon sources than DSM 20057, potentially owing to the abundance of genes involved in carbon metabolism, especially the Entner-Doudoroff pathway. The inability of γ-aminobutyric acid (GABA) production was evidenced by the lack of glutamate decarboxylase and glutamate/GABA antiporter genes in the new subgroup strains. Strain SG162 grew at 10-45 °C (optimum, 30 °C), pH 3.5-8.0, and 0-8 % (w/v) NaCl. Its genomic DNA G+C content was 44.1 mol%. The predominant fatty acids were C, C cyclo ω8, and summed feature 8. On the basis of the polyphasic characterization findings, strains SG162 and NK01 represent a novel subspecies of , for which the name subsp. subsp. nov. is proposed. The type strain is SG162 (=JCM 32599=DSM 107969), and strains CD034 and S42 are also transferred to subsp. .
两株革兰氏阳性、杆状、不运动、不产孢、过氧化氢酶阴性的细菌，分别命名为 SG162 和 NK01 株，分别从日本大米青贮料和全混合日粮青贮料中分离得到。基于 16S rRNA 基因序列相似性，最初将它们鉴定为 。然而，通过全基因组序列特征分析，这两株菌与 DSM 20057（=JCM 1115）分离成一个不同的分支，与可在公共序列数据库中获得基因组序列的菌株 CD034 和 S42 一起形成一个亚种内亚群。该亚群内的菌株彼此间的平均核苷酸同一性（ANI）为 99.4-99.7%，数字 DNA-DNA 杂交（dDDH）为 97.5-99.0%，而与 DSM 20057 的 ANI 为 96.9-97.0%，dDDH 为 76.0-76.6%。与 DSM 20057 相比，SG162 和 NK01 株能够作为唯一碳源利用更多的底物，这可能是由于参与碳代谢的基因丰富，特别是 Entner-Doudoroff 途径。新亚群菌株缺乏谷氨酸脱羧酶和谷氨酸/ GABA 反向转运基因，证明其不能产生 γ-氨基丁酸（GABA）。SG162 株在 10-45°C（最佳温度 30°C）、pH 3.5-8.0 和 0-8%（w/v）NaCl 下生长。其基因组 DNA G+C 含量为 44.1 mol%。优势脂肪酸为 C、C 环 ω8 和总和特征 8。基于多相特征研究结果，SG162 和 NK01 株代表 一个新的亚种，命名为 subsp. subsp. nov. 。模式菌株为 SG162（=JCM 32599=DSM 107969），菌株 CD034 和 S42 也被转移到 subsp. 。
