Table_1_Gemmatimonas groenlandica sp. nov. Is an Aerobic Anoxygenic Phototroph in the Phylum Gemmatimonadetes.XLSX

The bacterial phylum Gemmatimonadetes contains members capable of performing bacteriochlorophyll-based phototrophy (chlorophototrophy). However, only one strain of chlorophototrophic Gemmatimonadetes bacteria (CGB) has been isolated to date, hampering our further understanding of their photoheterotrophic lifestyle and the evolution of phototrophy in CGB. By combining a culturomics strategy with a rapid screening technique for chlorophototrophs, we report the isolation of a new member of CGB, Gemmatimonas (G.) groenlandica sp. nov., from the surface water of a stream in the Zackenberg Valley in High Arctic Greenland. Distinct from the microaerophilic G. phototrophica strain AP64T, G. groenlandica strain TET16T is a strictly aerobic anoxygenic phototroph, lacking many oxygen-independent enzymes while possessing an expanded arsenal for coping with oxidative stresses. Its pigment composition and infra-red absorption properties are also different from G. phototrophica, indicating that it possesses a different photosystem apparatus. The complete genome sequence of G. groenlandica reveals unique and conserved features in the photosynthesis gene clusters of CGB. We further analyzed metagenome-assembled genomes of CGB obtained from soil and glacier metagenomes from Northeast Greenland, revealing a wide distribution pattern of CGB beyond the stream water investigated.

芽单胞菌门（Gemmatimonadetes）包含能够进行基于细菌叶绿素的光能营养（chlorophototrophy）的类群。然而截至目前，仅分离得到1株光能营养型芽单胞菌门细菌（chlorophototrophic Gemmatimonadetes bacteria, CGB），这极大阻碍了我们对其光异养生活方式以及CGB光能营养演化进程的深入理解。本研究结合培养组学（culturomics）策略与光能营养菌快速筛选技术，从北极高地格陵兰扎科本谷某溪流的表层水体中，分离得到一株CGB新成员——格陵兰芽单胞菌（Gemmatimonas groenlandica）sp. nov.。与微需氧的光合芽单胞菌（G. phototrophica）AP64^T模式菌株不同，格陵兰芽单胞菌TET16^T为严格需氧不产氧光合营养菌，其缺乏多种氧非依赖型酶，但拥有更为丰富的抗氧化应激应答机制。该菌株的色素组成与红外吸收特性均与光合芽单胞菌存在差异，表明其拥有一套独特的光合系统装置。格陵兰芽单胞菌的完整基因组序列揭示了CGB光合基因簇独特且保守的特征。本研究进一步对格陵兰东北部土壤与冰川宏基因组中获取的CGB宏基因组组装基因组（metagenome-assembled genomes）进行分析，结果显示CGB的分布范围远超本次研究所调查的溪流水体范畴。