Agricultural Microbiology Division, National Institute of Agricultural Sciences, Rural Development Administration, Jeollabuk-do, 55365, Republic of Korea.
J Microbiol. 2020 Jun;58(6):445-455. doi: 10.1007/s12275-020-9596-3. Epub 2020 Mar 28.
The Lactobacillus genus is widely used for fermentation of plant materials and dairy products. These species are typically found in highly specialized environments, with the bee gut serving as one of the niche locations in which Lactobacillus is detected. Lactobacillus species isolated from the bee gut and bee-related habitats were phylogenetically classified into three distinct groups, Lactobacillus kunkeei, Firm-4, and Firm-5. The L. kunkeei group was clearly differentiated from other members of the Lactobacillus buchneri group isolated from non-bee habitats. In comparison with non-bee members of the L. buchneri group, three bee-symbiotic Lactobacillus groups had a small-sized genome with low G + C content and showed a sharp reduction in the number of genes involved in energy production, carbohydrate transport and metabolism, and amino acid transport and metabolism. In addition, all three groups lacked the mutY gene, which encodes A/G-specific adenine glycosylase. The phylogenetic dendrogram based on the presence or absence of 1,199 functional genes indicated that these bee-symbiotic groups experienced convergent evolution. The occurrence of convergent evolution is thought to stem from the three bee-symbiotic groups sharing a similar habitat, i.e., the bee gut. The causative factor underlying genomic reduction was postulated to be mutY, which was absent in all three groups. Here, a novel strain, BHWM-4, isolated from the gut of Bombus ignites was studied using polyphasic taxonomy and classified as a new member of the L. kunkeei group. The strain was Gram-positive, facultative anaerobic, and rod-shaped. The 16S ribosomal RNA gene sequence and genome analysis revealed that strain BHWM-4 was clustered into the L. kunkeei group, forming a compact cluster with L. kunkeei and Lactobacillus apinorum. Biochemical, chemotaxonomic, and genotypic data of strain BHWM-4 supports the proposal of a novel species, Lactobacillus bombintestini sp. nov., whose type strain is BHWM-4 (= KACC 19317 = NBRC 113067).
乳杆菌属广泛用于植物材料和乳制品的发酵。这些物种通常存在于高度专业化的环境中，而蜜蜂肠道是检测到乳杆菌的一个生态位位置。从蜜蜂肠道和与蜜蜂相关的栖息地分离出的乳杆菌物种在系统发育上被分为三个不同的组，即 L. kunkeei、Firm-4 和 Firm-5。L. kunkeei 组与从非蜜蜂栖息地分离出的其他乳杆菌buchneri 组成员明显不同。与乳杆菌buchneri 组的非蜜蜂成员相比，三个与蜜蜂共生的乳杆菌组具有小尺寸的基因组，GC 含量低，参与能量产生、碳水化合物运输和代谢以及氨基酸运输和代谢的基因数量急剧减少。此外，所有三个组都缺乏编码 A/G 特异性腺嘌呤糖苷酶的 mutY 基因。基于 1199 个功能基因的存在或不存在构建的系统发育树表明，这些与蜜蜂共生的组经历了趋同进化。趋同进化的发生被认为源于三个与蜜蜂共生的组具有相似的栖息地，即蜜蜂肠道。基因组减少的潜在原因是 mutY 缺失，所有三个组都缺失了 mutY 基因。在这里，从 Bombus ignites 肠道中分离出的新型菌株 BHWM-4 被用于多相分类学研究，并被分类为 L. kunkeei 组的新成员。该菌株为革兰氏阳性、兼性厌氧、杆状。16S 核糖体 RNA 基因序列和基因组分析表明，菌株 BHWM-4 聚类到 L. kunkeei 组，与 L. kunkeei 和 Lactobacillus apinorum 形成紧密聚类。菌株 BHWM-4 的生化、化学分类和基因型数据支持了一种新型物种的提出，即 Lactobacillus bombintestini sp. nov.，其模式株为 BHWM-4（=KACC 19317=NBRC 113067）。
