Han Tian Xu, Wang En Tao, Wu Li Juan, Chen Wen Feng, Gu Jin Gang, Gu Chun Tao, Tian Chang Fu, Chen Wen Xin
Key Laboratory of Agro-Microbial Resource and Application, Ministry of Agriculture/College of Biological Sciences, China Agricultural University, Beijing 100094, PR China.
Int J Syst Evol Microbiol. 2008 Jul;58(Pt 7):1693-9. doi: 10.1099/ijs.0.65568-0.
Thirty-one rhizobial strains isolated from nodules of legumes native of Xinjiang, China, were characterized. These strains were classified as belonging to the genus Rhizobium based on amplified 16S rDNA restriction analysis (ARDRA). The strains were distinguished from recognized Rhizobium species using analysis of 16S-23S rDNA intergenic spacers (IGS-RFLP), SDS-PAGE analysis of whole proteins and BOX-PCR; the test strains always formed a distinct cluster with patterns that were quite different from those of the reference rhizobial strains used. According to the phylogenetic analysis based on the 16S rRNA gene, the test strains belonged to the genus Rhizobium, with Rhizobium tropici, Rhizobium rhizogenes and Rhizobium lusitanum as the closest related species, with 99.6, 99.2 and 99.4 % sequence similarities, respectively, between the type strains of the three Rhizobium species and strain CCBAU 83401(T). Phylogenetic analyses of the representative strains using IGS and atpD, recA and glnII genes all confirmed the phylogenetic arrangements obtained using the 16S rRNA gene. The DNA-DNA relatedness values between strain CCBAU 83401(T) and strains CCBAU 83364, CCBAU 83345 and CCBAU 83523 ranged from 80.8 to 100 %, showing that they belong to the same species. The DNA-DNA relatedness between strain CCBAU 83401(T) and R. tropici IIB CIAT 899(T), R. tropici IIA CFN 299, R. rhizogenes LMG 150(T) and R. lusitanum P1-7(T) were 26.9, 27.7, 38.2 and 22.6 %, respectively, clearly indicating that strain CCBAU 83401(T) represents a novel species. Phenotypic characterization of four representative strains, CCBAU 83401(T), CCBAU 83364, CCBAU 83345 and CCBAU 83523, showed several distinctive features that differentiated them from closely related species. The 31 strains had identical nodD and nifH genes, which were very similar to those of the bean-nodulating R. lusitanum, Devosia neptuniae and R. tropici IIB. Based upon these results, the strains from this study are considered to represent a novel species, for which the name Rhizobium multihospitium sp. nov. is proposed. The DNA G+C content ranged from 65.3 to 66.0 mol% (T(m)). The type strain is CCBAU 83401(T) (=LMG 23946(T)=HAMBI 2975(T)), which nodulates Robinia pseudoacacia, but not Leucaena leucocephala, Phaseolus vulgaris, Pisum sativum or Medicago sativa.
对从中国新疆本地豆科植物根瘤中分离出的31株根瘤菌菌株进行了特性分析。基于扩增的16S rDNA限制性分析（ARDRA），这些菌株被归类为根瘤菌属。使用16S - 23S rDNA基因间隔区分析（IGS - RFLP）、全蛋白的SDS - PAGE分析和BOX - PCR将这些菌株与已确认的根瘤菌物种区分开来；测试菌株总是形成一个独特的聚类，其模式与所使用的参考根瘤菌菌株的模式有很大不同。根据基于16S rRNA基因的系统发育分析，测试菌株属于根瘤菌属，其中热带根瘤菌、发根根瘤菌和卢西塔尼亚根瘤菌是最密切相关的物种，这三种根瘤菌物种的模式菌株与CCBAU 83401(T)菌株之间的序列相似性分别为99.6%、99.2%和99.4%。使用IGS以及atpD、recA和glnII基因对代表性菌株进行的系统发育分析均证实了使用16S rRNA基因获得的系统发育排列。CCBAU 83401(T)菌株与CCBAU 83364、CCBAU 83345和CCBAU 83523菌株之间的DNA - DNA相关性值在80.8%至100%之间，表明它们属于同一物种。CCBAU 83401(T)菌株与热带根瘤菌IIB CIAT 899(T)、热带根瘤菌IIA CFN 299、发根根瘤菌LMG 150(T)和卢西塔尼亚根瘤菌P1 - 7(T)之间的DNA - DNA相关性分别为26.9%、27.7%、38.2%和22.6%，清楚地表明CCBAU 83401(T)菌株代表一个新物种。对四个代表性菌株CCBAU 83401(T)、CCBAU 83364、CCBAU 83345和CCBAU 83523的表型特征分析显示出一些使其与密切相关物种区分开来的独特特征。这31株菌株具有相同的nodD和nifH基因，这些基因与能使豆类结瘤的卢西塔尼亚根瘤菌、海王星德沃西亚菌和热带根瘤菌IIB的基因非常相似。基于这些结果，本研究中的菌株被认为代表一个新物种，为此提出了多宿主根瘤菌（Rhizobium multihospitium sp. nov.）这一名称。DNA G + C含量范围为65.3至66.0 mol%（T(m)）。模式菌株是CCBAU 83401(T)（=LMG 23946(T)=HAMBI 2975(T)），它能使刺槐结瘤，但不能使银合欢、菜豆、豌豆或紫花苜蓿结瘤。
