Chen Wen Hao, Yang Sheng Hui, Li Zhao Hu, Zhang Xiao Xia, Sui Xin Hua, Wang En Tao, Chen Wen Xin, Chen Wen Feng
State Key Laboratory of Agro-Biotechnology; College of Biological Sciences and Rhizobium Research Center, China Agricultural University; MOA Key Laboratory of Soil Microbiology; Beijing 100193, PR China; Engineering Research Centre of Plant Growth Regulators, Ministry of Education; College of Agronomy and Biotechnology, China Agricultural University; Beijing 100193, PR China; College of Life Science & Food Engineering, Yibin University, Yibin 644000, Sichuan Province, PR China.
State Key Laboratory of Agro-Biotechnology; College of Biological Sciences and Rhizobium Research Center, China Agricultural University; MOA Key Laboratory of Soil Microbiology; Beijing 100193, PR China; Shandong Shofine Seed Technology Co. Ltd., Jiaxiang 272400, PR China.
Syst Appl Microbiol. 2017 Apr;40(3):144-149. doi: 10.1016/j.syapm.2017.01.002. Epub 2017 Feb 2.
Two bacterial strains isolated from root nodules of soybean were characterized phylogenetically as members of a distinct group in the genus Ensifer based on 16S rRNA gene comparisons. They were also verified as a separated group by the concatenated sequence analyses of recA, atpD and glnII (with similarities ≤93.9% to the type strains for defined species), and by the average nucleotide identities (ANI) between the whole genome sequence of the representative strain CCBAU 251167 and those of the closely related strains in Ensifer glycinis and Ensifer fredii (90.5% and 90.3%, respectively). Phylogeny of symbiotic genes (nodC and nifH) grouped these two strains together with some soybean-nodulating strains of E. fredii, E. glycinis and Ensifer sojae. Nodulation tests indicated that the representative strain CCBAU 251167 could form root nodules with capability of nitrogen fixing on its host plant and Glycine soja, Cajanus cajan, Vigna unguiculata, Phaseolus vulgaris and Astragalus membranaceus, and it formed ineffective nodules on Leucaena leucocephala. Strain CCBAU 251167 contained fatty acids 18:1 ω9c, 18:0 iso and 20:0, differing from other related strains. Utilization of l-threonine and d-serine as carbon source, growth at pH 6.0 and intolerance of 1% (w/v) NaCl distinguished strain CCBAU 251167 from other type strains of the related species. The genome size of CCBAU 251167 was 6.2Mbp, comprising 7,581 predicted genes with DNA G+C content of 59.9mol% and 970 unique genes. Therefore, a novel species, Ensifer shofinae sp. nov., is proposed, with CCBAU 251167 (=ACCC 19939=LMG 29645) as type strain.
基于16S rRNA基因比较，从大豆根瘤中分离出的两株细菌在系统发育上被鉴定为Ensifer属中一个独特类群的成员。通过recA、atpD和glnII的串联序列分析（与已定义物种的模式菌株相似度≤93.9%），以及代表性菌株CCBAU 251167的全基因组序列与Ensifer glycinis和Ensifer fredii中密切相关菌株的全基因组序列之间的平均核苷酸同一性（ANI，分别为90.5%和90.3%），它们也被确认为一个独立的类群。共生基因（nodC和nifH）的系统发育将这两株菌株与一些fredii大豆根瘤菌、glycinis大豆根瘤菌和sojae大豆根瘤菌的大豆结瘤菌株归为一类。结瘤试验表明，代表性菌株CCBAU 251167能够在其寄主植物以及野生大豆、木豆、豇豆、菜豆和膜荚黄芪上形成具有固氮能力的根瘤，而在银合欢上形成无效根瘤。菌株CCBAU 251167含有脂肪酸18:1 ω9c、18:0 iso和20:0，与其他相关菌株不同。以L-苏氨酸和D-丝氨酸作为碳源、在pH 6.0条件下生长以及对1%（w/v）NaCl不耐受等特性使菌株CCBAU 251167与相关物种的其他模式菌株区分开来。CCBAU 251167的基因组大小为6.2Mbp，包含7581个预测基因，DNA G+C含量为59.9mol%，有970个独特基因。因此，提出了一个新物种，即肖氏恩氏菌（Ensifer shofinae sp. nov.），以CCBAU 251167（=ACCC 19939=LMG 29645）作为模式菌株。
