de Matos Gustavo Feitosa, Zilli Jerri Edson, de Araújo Jean Luiz Simões, Parma Marcia Maria, Melo Itamar Soares, Radl Viviane, Baldani José Ivo, Rouws Luc Felicianus Marie
Embrapa Agrobiologia, Rodovia BR 465 km 7, Seropédica, Rio De Janeiro, 23890-000, Brazil.
Universidade Federal Rural do Rio de Janeiro, Curso de Pós-graduação em Fitotecnia, Rodovia BR 465 km 07, Seropédica, Rio De Janeiro, 23890-000, Brazil.
Arch Microbiol. 2017 Nov;199(9):1251-1258. doi: 10.1007/s00203-017-1398-6. Epub 2017 Jun 10.
Members of the genus Bradyrhizobium are well-known as nitrogen-fixing microsymbionts of a wide variety of leguminous species, but they have also been found in different environments, notably as endophytes in non-legumes such as sugarcane. This study presents a detailed polyphasic characterization of four Bradyrhizobium strains (type strain BR 10280), previously isolated from roots of sugarcane in Brazil. 16S rRNA sequence analysis, multilocus sequence analysis (MLSA) and analysis of the 16S-23S rRNA internal transcribed spacer showed that these strains form a novel clade close to, but different from B. huanghuaihaiense strain CCBAU 23303. Average nucleotide identity (ANI) analyses confirmed that BR 10280 represents a novel species. Phylogenetic analysis based on nodC gene sequences also placed the strains close to CCBAU 23303, but different from this latter strain, the sugarcane strains did not nodulate soybean, although they effectively nodulated Vigna unguiculata, Cajanus cajan and Macroptilium atropurpureum. Physiological traits are in agreement with the placement of the strains in the genus Bradyrhizobium as a novel species for which the name Bradyrhizobium sacchari sp. nov. is proposed.
慢生根瘤菌属的成员作为多种豆科植物的固氮微共生体而广为人知，但它们也在不同环境中被发现，特别是作为甘蔗等非豆科植物中的内生菌。本研究对四株慢生根瘤菌菌株（模式菌株BR 10280）进行了详细的多相表征，这些菌株先前从巴西甘蔗根部分离得到。16S rRNA序列分析、多位点序列分析（MLSA）以及16S - 23S rRNA内部转录间隔区分析表明，这些菌株形成了一个新的进化分支，与黄淮海慢生根瘤菌菌株CCBAU 23303相近但不同。平均核苷酸同一性（ANI）分析证实BR 10280代表一个新物种。基于nodC基因序列的系统发育分析也将这些菌株置于与CCBAU 23303相近的位置，但与后一菌株不同的是，甘蔗菌株不能使大豆结瘤，尽管它们能有效地使豇豆、木豆和大翼豆结瘤。生理特征与这些菌株在慢生根瘤菌属中作为一个新物种的分类地位相符，为此提出新名称慢生根瘤菌甘蔗种（Bradyrhizobium sacchari sp. nov.）。
