Tohya Mari, Arai Sakura, Tomida Junko, Watanabe Takayasu, Kawamura Yoshiaki, Katsumi Masanori, Ushimizu Mariko, Ishida-Kuroki Kasumi, Yoshizumi Mina, Uzawa Yutaka, Iguchi Shigekazu, Yoshida Atsushi, Kikuchi Ken, Sekizaki Tsutomu
Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Department of Microbiology, School of Pharmacy, Aichi-gakuin University, 1-100, Kusumoto-cho, Nagoya-shi, Aichi-ken 464-8650, Japan.
Int J Syst Evol Microbiol. 2017 Sep;67(9):3660-3665. doi: 10.1099/ijsem.0.002204. Epub 2017 Aug 25.
To clarify the taxonomic classification of Streptococcus suis serotype 33, we performed biochemical and molecular genetic analyses using isolates (GUT-183, GUT-184, GUT-185, GUT-186, GUT-187T, GUT-188, GUT-189, GUT-190, GUT-191, GUT-192 and GUT-193) from bovine endocarditis. A comparative sequence analysis showed 99.2-100 % sequence similarity among the reference strain of S. suis serotype 33 and our isolates for the 16S rRNA gene. These similarities were higher than those between the isolate GUT-187T and S. suis and other streptococci. Comparison of sodA genes also showed high degrees of similarities among the reference strain of S. suis serotype 33 and our isolates (99.7-100 %), which were higher than those between the GUT-187T and S. suis and other streptococci. DNA-DNA relatedness among three isolates (GUT-186, GUT-187T, the reference strain of S. suis serotype 33) was over 76.7 %. In contrast, the relatedness between GUT-187T and the other streptococcal species (S. suis, Streptococcus parasuis, Streptococcus acidominimus and Streptococcus porci) was 8.4-24.9 %. Phylogenetic analyses showed that the isolates did not affiliate closely to any known species of the genus Streptococcus. Moreover, GUT-187T could be distinguished from S. suis and other closely related species of genus Streptococcus using biochemical tests. On the basis of the phenotypic and molecular genetic data, we propose that the isolates of S. suis serotype 33 should be classified into the genus Streptococcus, Streptococcus ruminantium sp. nov. with the type strain GUT-187T (=DSM 104980T=JCM 31869T).
为明确猪链球菌33型的分类地位，我们使用从牛心内膜炎分离出的菌株（GUT-183、GUT-184、GUT-185、GUT-186、GUT-187T、GUT-188、GUT-189、GUT-190、GUT-191、GUT-192和GUT-193）进行了生化和分子遗传学分析。比较序列分析显示，猪链球菌33型参考菌株与我们的分离株在16S rRNA基因上的序列相似性为99.2%-100%。这些相似性高于分离株GUT-187T与猪链球菌及其他链球菌之间的相似性。sodA基因的比较也显示，猪链球菌33型参考菌株与我们的分离株之间具有高度相似性（99.7%-100%），高于GUT-187T与猪链球菌及其他链球菌之间的相似性。三株分离株（GUT-186、GUT-187T、猪链球菌33型参考菌株）之间的DNA-DNA相关性超过76.7%。相比之下，GUT-187T与其他链球菌属物种（猪链球菌、副猪链球菌、嗜酸链球菌和猪链球菌）之间的相关性为8.4%-24.9%。系统发育分析表明，这些分离株与链球菌属的任何已知物种都没有紧密的亲缘关系。此外，通过生化试验可以将GUT-187T与猪链球菌及链球菌属其他密切相关的物种区分开来。基于表型和分子遗传学数据，我们建议将猪链球菌33型分离株归入链球菌属，命名为反刍链球菌新种，模式菌株为GUT-187T（=DSM 104980T=JCM 31869T）。
