title: Mesorhizobium qingshengii sp. nov., isolated from effective nodules of Astragalus sinicus.
abstract: In a study on the diversity of rhizobia isolated from root nodules of Astragalus sinicus, five strains showed identical 16S rRNA gene sequences. They were related most closely to the type strains of Mesorhizobium loti, Mesorhizobium shangrilense, Mesorhizobium ciceri and Mesorhizobium australicum, with sequence similarities of 99.6-99.8%. A polyphasic approach, including 16S-23S intergenic spacer (IGS) RFLP, comparative sequence analysis of 16S rRNA, atpD, glnII and recA genes, DNA-DNA hybridization and phenotypic tests, clustered the five isolates into a coherent group distinct from all recognized Mesorhizobium species. Except for strain CCBAU 33446, from which no symbiotic gene was detected, the four remaining strains shared identical nifH and nodC gene sequences and nodulated with Astragalus sinicus. In addition, these five strains showed similar but different fingerprints in IGS-RFLP and BOX-repeat-based PCR, indicating that they were not clones of the same strain. They were also distinguished from recognized Mesorhizobium species by several phenotypic features and fatty acid profiles. Based upon all the results, we suggest that the five strains represent a novel species for which the name Mesorhizobium qingshengii sp. nov. is proposed. The type strain is CCBAU 33460(T) (=CGMCC 1.12097(T)=LMG 26793(T)=HAMBI 3277(T)). The DNA G+C content of the type strain is 59.52 mol% (Tm).
authors.affiliation: State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: Wen Tao
authors.initials: WT
authors.lastname: Zheng
authors.affiliation: State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: Xin Hua
authors.initials: XH
authors.lastname: Sui
authors.affiliation: Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.
authors.forename: Xiao Xia
authors.initials: XX
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: Jun Jie
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 11340 México DF, Mexico.|State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, PR China.
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D027883:Astragalus Plant / Q000382:microbiology*; D015373:Bacterial Typing Techniques; D001482:Base Composition; D004269:DNA, Bacterial / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis; D005798:Genes, Bacterial; D059128:Mesorhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D009693:Nucleic Acid Hybridization; D010743:Phospholipids / Q000032:analysis; D010802:Phylogeny; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000382:microbiology*; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D005227:Fatty Acids; D010743:Phospholipids; D012336:RNA, Ribosomal, 16S; D014451:Ubiquinone; C024989:coenzyme Q10