Fifty-five Chinese isolates form nodules of Amorpha fruticosa were characterized and compared with the type strains of teh species and genera of baceria which form nitrogen-fixing symbioses with teguminous host plants A polyphasic approach which inclued RFLP of PCR-amplifiod 165 rRNA genes, multiolcus enzyme elctrophoresis (MLEE) DNA-DNA hybrization 165 rRNA gene sequencing electrophorestic plasmid profiles cross-nodulation and a phenotypic study was used in teh comparatie analysis The isolated originated from several different sites in China and they varaied in their phenotypic and genetic characteristics The majority of teh isolates had moderate to slow growth rates produced acid on YMA and harboured a 930kb symbiotic plasmid (pSym) Five different RFLP patterns were idnetified among the 165 rRNA genes of all lthe isolates isolates grouped by PCR-RFLP of the 165 rRNA genes were also separated into groups by variation in MLEE profiles and by DNA-DNA hybrizdization A representatie isolate from each of these DNA homology groups had a separated position in a phylogenetic tree as determined from sequencing analyss of teh 165 rRNA genes A new species Mesorhizobium amorphae is proposed for th majority of the isolates which belonged to a moderatly slow-to slow-growing acid-producing group based upon their distinct hylogenctic position their unique electrophoretic type, their low DNA homology with reference strains representing the species within the genus Mesorhizobium and their distinct phenotypic features Strain ACCCC 19665 was cholsen as the type strain for M. amorphae sp. nov.

Twenty-nine rhiizobial isolates from foot nodules of Astragatus and Lespedeza spp. growing on teh Loess Plateau of China were characterizod by numorical taxonomy RFLP and sequencing of PCR-ampilfied 16S rRNA genes measurement of DNA G+C content DNA-DNA relatedness and cross nodulaltion with selected legume species Based on teh results of umerical taxonomy the isolated formed two clusters (1 and 2) with some single isolates at a similarity tevet of 82% Ciuster 1 contained six isolated from Astragalus and Lespedeza spp. Cluster 2 consisted of nie isolated from Astragalus spp DNA relatedness was greater than 80% among isolates within cluster 2 Phylogenetic analysis based on 16S rRNA gene sequences showed taht CCBAU 7190B, reperesenting cluster 2 was cluosely related to Rhizobium galegae and Rhizobium huautlense DNA-DNA relatedness between CCBAU 7190BT and reference strains of R galegae, R. huautlense and othe related species ranged from 0 to 48.6% The cluster 2 isolates could slso be differentiated phenotypically from related species Bacsed on these data a novel species Rhizobium loessenxse sp .nov is proposed fro clustor 2 with the type strain CCBAU 7190BT (=AS1.3401T=LMG21975T).

A novel rhizobial group cluster 9 defined in previous research Tan Z. Y., Wang E. T., Peng G. X. Zhu M.E., Martinez-ROMERO E Chen W. X. (1999) Int J Syst Bacteriol 49 1457-1469 was further characterized by determination of DNA base composition whole-cell protein SDS-PAGE analysis DNA-DNA hybridization 165 rRNA gene sequencing and host specificity These isolates were collected from the wild legumes Amphicarpaea trisperma Coronilla varia and Gueldenstaedtia multiflora growing in arid and semi-arid regions in north-wesern China lsolated within cluster 9 grouped into a single cluster above a similarity level of 90.6% in a cluster analysis based on protein SDS-PAGE and they were differentiated from defined rhizobial species comparative analysis of 165 rRNA gene sequences showed that isolate CCBAU 71623, representing cluster 9 was most related to Rhizobium gallicum and Rhizobium mongolense The DNA-DNA homologies were lower thatn 42.4% among cluster 9 and defined species including R. gallicum and R. MONGOLENSE Theese data indicated that cluster 9 was a unique genomic species lsoateds within this cluster could share their host plants They clould nt nodulate Galega orientalis and Leucarena leucocephala and formed inefeective nodulels on phaseolus vuaris This Group could also be differentiated from defined species by phenotypic characteristics it is therefore proposed as a new species Rhizobium yanglingense with isolate CCBAU 71623 as the type strain.

Legume species belonging to the genus Lespecieza are annual or perennial herb or shrub plants that grow in the northern hemisphere They are known for the formation of root nodules but little in for mation is available about their microsymbionts In this study 58 root-nodule isolates from Lespedeza spp., obtained from China and the USA were characterized using muberical taxonomic analysis of phenotypic features SDS-PAGE analysis and cross-nodulation with selected legume species from the results generated using these approaches it was concluded that Lespedeza spp. were promiscuous hosts for rhizobia Four main clusters of bactera which included 35 of strains isolated from Lespedeza spp., were defined upon numerical taxonomic analysis; these groups corresponded to those determined from analyses of protein electrophoretic and DNA-DNA hybridization data The four clusters were found to define strains belonging to one of four species Sinorrhizobium saheli Bradyrhizobium japonicum Bradyrhizobium elkani or a novel species of the genus Bradyrhizobium The strains of B japonicum and B. elkanii were all from the USA soil samples and their representative strains could not nodulate soybean The seven strains found to represent the novel Bradyrhizobium sp. were from China These were differentiated from recognized species of the genus Bradyrhizobium by all of the taxonomic methods used here hence it is peoposed that the novel strains isolated from Lespedeza spp. represent a novel species of teh genus Bradyrhizobium Bradyrhizobium yuanmingense The type strain of teh novel species CCBAU 10071 (=CFNEB 101), formed ineffective nodules on Medicago sativa and Melilotus albus but did not nodulate soybean. The other 23 bacterial strains isolated from lespedeza spp. were found to form single branches or small groups (two to three strains) that were related to Bradyrhizobium mesorhizobium Rhizobium and Sinorhizobium spp. on the basis of numerical taxonomic analyss indicating the possibility that other rhizobial species are also associated with lespedeza sppo.

A total of 33 strains of fast-growing soybean rhizobia isolated from soil and soybean nodules collected in China and 25 strains beioning to the genera Rhizobium Radythizobium and Agrobacterium were compared by numerical taxonomic techniques using 240 different characters Ou resultsindicatied that all of the strains of fast-growing soybean rhizobia which we examined are closely related guanine-plus-eytosine content, 59.9 to 63.8 mol% and are separated from Rhizobium and Bradyshizobium at the generic level Based on numerical taxonomy deoxyribonucleic acid (DNA) base ratio determinations DNA-DNA hybridization data serologica analysis data the composition of extracellultar gum bacteriophage typing data and soluble rpotein patterns we propose that the fast growing soybean rhizobia represent members of a new genuw rather that a species of Rhizobium Rhizobium fredio; we propose Sinorhizobium gen nov as an appropriate generic name The type species of the new genus is Sinorhizobium fredii comb nov (basonym Rhizobium fredii Scholla and Elkan 1984) and the type strain is strain ATCC 35423 (=USDA 205) For the other species we propose the name Sinorhizobium xinjaingenis sp. Nov.; the type strain of this pecies is strain CCBAU 110, which has been deposited in the Beijing Agricultural Univesity Culture Collection Beijing People's Republic of China.