Utami Yuniar Devi, Kuwahara Hirokazu, Murakami Takumi, Morikawa Takahiro, Sugaya Kaito, Kihara Kumiko, Yuki Masahiro, Lo Nathan, Deevong Pinsurang, Hasin Sasitorn, Boonriam Warin, Inoue Tetsushi, Yamada Akinori, Ohkuma Moriya, Hongoh Yuichi
Department of Biological Sciences, Tokyo Institute of Technology.
Biomass Research Platform Team, RIKEN Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science.
Microbes Environ. 2018 Mar 29;33(1):50-57. doi: 10.1264/jsme2.ME17137. Epub 2018 Mar 8.
Termite guts harbor diverse yet-uncultured bacteria, including a non-photosynthetic cyanobacterial group, the class "Melainabacteria". We herein reported the phylogenetic diversity of "Melainabacteria" in the guts of diverse termites and conducted a single-cell genome analysis of a melainabacterium obtained from the gut of the termite Termes propinquus. We performed amplicon sequencing of 16S rRNA genes from the guts of 60 termite and eight cockroach species, and detected melainabacterial sequences in 48 out of the 68 insect species, albeit with low abundances (0.02-1.90%). Most of the melainabacterial sequences obtained were assigned to the order "Gastranaerophilales" and appeared to form clusters unique to termites and cockroaches. A single-cell genome of a melainabacterium, designated phylotype Tpq-Mel-01, was obtained using a fluorescence-activated cell sorter and whole genome amplification. The genome shared basic features with other melainabacterial genomes previously reconstructed from the metagenomes of human and koala feces. The bacterium had a small genome (~1.6 Mb) and possessed fermentative pathways possibly using sugars and chitobiose as carbon and energy sources, while the pathways for photosynthesis and carbon fixation were not found. The genome contained genes for flagellar components and chemotaxis; therefore, the bacterium is likely motile. A fluorescence in situ hybridization analysis showed that the cells of Tpq-Mel-01 and/or its close relatives are short rods with the dimensions of 1.1±0.2 μm by 0.5±0.1 μm; for these bacteria, we propose the novel species, "Candidatus Gastranaerophilus termiticola". Our results provide fundamental information on "Melainabacteria" in the termite gut and expand our knowledge on this underrepresented, non-photosynthetic cyanobacterial group.
白蚁肠道中含有多种尚未培养的细菌，包括一个非光合蓝细菌类群，即“黑素杆菌纲”。我们在此报告了不同白蚁肠道中“黑素杆菌纲”的系统发育多样性，并对从近白蚁肠道中获得的一种黑素杆菌进行了单细胞基因组分析。我们对60种白蚁和8种蟑螂肠道中的16S rRNA基因进行了扩增子测序，在68种昆虫中有48种检测到了黑素杆菌序列，尽管丰度较低（0.02 - 1.90%）。获得的大多数黑素杆菌序列被归入“嗜胃厌氧杆菌目”，并且似乎形成了白蚁和蟑螂特有的簇。使用荧光激活细胞分选仪和全基因组扩增技术获得了一种黑素杆菌的单细胞基因组，命名为系统发育型Tpq - Mel - 01。该基因组与先前从人类和考拉粪便宏基因组中重建的其他黑素杆菌基因组具有基本特征。该细菌基因组较小（约1.6 Mb），拥有可能利用糖和壳二糖作为碳源和能源的发酵途径，而未发现光合作用和碳固定途径。基因组包含鞭毛成分和趋化作用的基因；因此，该细菌可能具有运动性。荧光原位杂交分析表明，Tpq - Mel - 01及其近亲的细胞是短杆状，尺寸为1.1±0.2μm×0.5±0.1μm；对于这些细菌，我们提出了新物种“暂定嗜胃厌氧杆菌白蚁种”。我们的结果提供了关于白蚁肠道中“黑素杆菌纲”的基础信息，并扩展了我们对这个代表性不足的非光合蓝细菌类群的认识。
