State Key Lab of Agrobiotechnology, Ministry of Agriculture Key Lab of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
State Key Lab of Agrobiotechnology, Ministry of Agriculture Key Lab of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
Syst Appl Microbiol. 2019 Sep;42(5):126002. doi: 10.1016/j.syapm.2019.126002. Epub 2019 Jul 19.
Nine slow-growing rhizobia isolated from effective nodules on peanut (Arachis hypogaea) were characterized to clarify the taxonomic status using a polyphasic approach. They were assigned to the genus Bradyrhizobium on the basis of 16S rRNA sequences. MLSA of concatenated glnII-recA-dnaK genes classified them into three species represented by CCBAU 53390, CCBAU 51670 and CCBAU 51778, which presented the closest similarity to B. guangxiense CCBAU 53363, B. guangdongense CCBAU 51649 and B. manausense BR 3351, B. vignae 7-2 and B. forestalis INPA 54B, respectively. The dDDH (digital DNA-DNA hybridization) and ANI (Average Nucleotide Identity) between the genomes of the three representative strains and type strains for the closest Bradyrhizobium species were less than 42.1% and 91.98%, respectively, below the threshold of species circumscription. Effective nodules could be induced on peanut and Lablab purpureus by all representative strains, while Vigna radiata formed effective nodules only with CCBAU 53390 and CCBAU 51778. Phenotypic characteristics including sole carbon sources and growth features supported the phylogenetic results. Based on the genotypic and phenotypic features, strains CCBAU 53390, CCBAU 51670 and CCBAU 51778 are designated the type strains of three novel species, for which the names Bradyrhizobium nanningense sp. nov., Bradyrhizobium guangzhouense sp. nov. and Bradyrhizobium zhanjiangense sp. nov. are proposed, respectively.
从有效花生（Arachis hypogaea）根瘤中分离出的 9 株缓慢生长的根瘤菌，通过多相分类法对其进行了特征描述，以明确其分类地位。根据 16S rRNA 序列，它们被归为慢生根瘤菌属。glnII-recA-dnaK 基因的 MLSA 将它们分为三个种，代表菌株为 CCBAU 53390、CCBAU 51670 和 CCBAU 51778，它们与 B. guangxiense CCBAU 53363、B. guangdongense CCBAU 51649 和 B. manausense BR 3351、B. vignae 7-2 和 B. forestalis INPA 54B 的相似度最高。三个代表菌株与最接近的慢生根瘤菌属种的模式菌株之间的 dDDH（数字 DNA-DNA 杂交）和 ANI（平均核苷酸同一性）分别小于 42.1%和 91.98%，低于种界定的阈值。所有代表菌株都能在花生和豇豆上诱导有效根瘤，而 Vigna radiata 仅与 CCBAU 53390 和 CCBAU 51778 形成有效根瘤。包括唯一碳源和生长特征在内的表型特征支持了系统发育结果。基于基因型和表型特征，菌株 CCBAU 53390、CCBAU 51670 和 CCBAU 51778 被指定为三个新种的模式菌株，分别命名为南宁慢生根瘤菌（Bradyrhizobium nanningense）sp. nov.、广州慢生根瘤菌（Bradyrhizobium guangzhouense）sp. nov.和湛江慢生根瘤菌（Bradyrhizobium zhanjiangense）sp. nov.。
