Varsha Kontham Kulangara, Nampoothiri Kesavan Madhavan
Biotechnology Division, CSIR - National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum-695 019, Kerala, India.
Int J Syst Evol Microbiol. 2016 Oct;66(10):3805-3809. doi: 10.1099/ijsem.0.001268. Epub 2016 Aug 4.
A taxonomic investigation was performed on a Gram-stain-positive coccus, designated strain BSN307T, isolated from gaur (Indian bison, Bos gaurus) dung based on phenotypic and molecular approaches. Based on the biochemical tests, cellular morphology and 16S rRNA gene sequence similarity, this strain was found to be a member of the genus Lactococcus and closely related to Lactococcus garvieae ATCC 49156T (99.6 % 16S rRNA gene sequence similarity) and L.actococcus formosensis 516T (99.0 %). However, DNA-DNA hybridization studies showed that the level of relatedness between strain BSN307T and L. garvieae ATCC 49156T was 75.8 %, suggesting that it represented a novel subspecies of L. garvieae. The inability to grow in brain heart infusion (BHI) medium at pH 9.6, in tryptic soy agar (TSA) with 4 % (w/v) NaCl and at 42 °C (MRS agar) clearly differentiated BSN307T from L. garvieae ATCC 49156T. Rep-PCR fingerprint patterns, substantial differences in summed feature 8 (C18 : 1ω7c/C18 : 1ω6c), C19 : 0 cyclo ω8c and C16 : 0 also differentiated strain BSN307T from the reference strain of L. garvieae. Moreover, analysis of the housekeeping genes pheS and rpoA revealed sequence similarities that were at the limit for species differentiation (92.2 and 97.8 %, respectively). Combined genotypic and phenotypic data indicate that strain BSN307T represents a subspecies of L. garvieae for which the name Lactococcus garvieae subsp. bovis subsp. nov. is proposed. The type strain is BSN307T (=DSM 100577 T=MCC 2824T=KCTC 21083T).
基于表型和分子方法，对从印度野牛（Bos gaurus）粪便中分离出的一株革兰氏阳性球菌（命名为菌株BSN307T）进行了分类学研究。基于生化试验、细胞形态学和16S rRNA基因序列相似性，发现该菌株是乳球菌属的成员，与加氏乳球菌ATCC 49156T（16S rRNA基因序列相似性为99.6%）和台湾乳球菌516T（99.0%）密切相关。然而，DNA-DNA杂交研究表明，菌株BSN307T与加氏乳球菌ATCC 49156T之间的相关性水平为75.8%，这表明它代表了加氏乳球菌的一个新亚种。在pH 9.6的脑心浸液（BHI）培养基中、含有4%（w/v）NaCl的胰蛋白胨大豆琼脂（TSA）上以及42°C（MRS琼脂）条件下无法生长，这清楚地将BSN307T与加氏乳球菌ATCC 49156T区分开来。重复PCR指纹图谱、在总和特征8（C18:1ω7c/C18:1ω6c）、C19:0环ω8c和C16:0方面的显著差异也将菌株BSN307T与加氏乳球菌的参考菌株区分开来。此外，看家基因pheS和rpoA的序列相似性分析显示，其处于物种分化的极限水平（分别为92.2%和97.8%）。综合的基因型和表型数据表明，菌株BSN307T代表了加氏乳球菌的一个亚种，为此提出了新名称牛源加氏乳球菌亚种（Lactococcus garvieae subsp. bovis subsp. nov.）。模式菌株为BSN307T（=DSM 100577T=MCC 2824T=KCTC 21083T）。
