RESUMO
In this work we analysed different chromosomal and symbiotic markers in rhizobial strains nodulating Lupinus albus (white lupin) in several continents. Collectively the analysis of their rrs and atpD genes, and 16S-23S intergenic spacers (ITS), showed that they belong to at least four chromosomal lineages within the genus Bradyrhizobium. Most isolates from the Canary Islands (near to the African continent) grouped with some strains isolated on mainland Spain and were identified as Bradyrhizobium canariense. These strains are divided into two ITS subgroups coincident with those previously described from isolates nodulating Ornithopus. The remaining strains isolated on mainland Spain grouped with most isolates from Chile (American continent) forming a new lineage related to Bradyrhizobium japonicum. The strains BLUT2 and ISLU207 isolated from the Canary Islands and Chile, respectively, formed two new lineages phylogenetically close to different species of Bradyrhizobium depending on the marker analyzed. The analysis of the nodC gene showed that all strains nodulating L. albus belong to the biovar genistearum; nevertheless they form four different nodC lineages of which lineage C is at present exclusively formed by L. albus endosymbionts isolated from different continents.
Assuntos
Bradyrhizobium/classificação , Bradyrhizobium/fisiologia , Lupinus/microbiologia , Lupinus/fisiologia , Nodulação , Simbiose , Proteínas de Bactérias/genética , Bradyrhizobium/genética , Chile , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico , Dados de Sequência Molecular , N-Acetilglucosaminiltransferases/genética , Filogenia , RNA Ribossômico 16S/genética , RNA Ribossômico 23S/genética , Análise de Sequência de DNA , EspanhaRESUMO
Two sporulating bacterial strains designated CECAP06(T) and CECAP16 were isolated from the rhizosphere of the legume Cicer arietinum in Argentina. Almost-complete 16S rRNA gene sequences identified the isolates as a Paenibacillus species. It was most closely related to Paenibacillus cineris LMG 18439(T) (99.6 % sequence similarity), Paenibacillus favisporus LMG 20987(T) (99.4 % sequence similarity) and Paenibacillus azoreducens DSM 13822(T) (97.7 % sequence similarity). The cells of this novel species were motile, sporulating, rod-shaped, Gram-positive and strictly aerobic. The predominant fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). The DNA G+C content of strains CECAP06(T) and CECAP16 was 51.3 and 50.9 mol%, respectively. Growth was observed from many carbohydrates, but gas production was not observed from glucose. Catalase and oxidase activities were present. The isolates produced beta-galactosidase and hydrolysed aesculin. Gelatinase, caseinase and urease were not produced. The results of DNA-DNA hybridization showed that the strains from this study constitute a novel species of the genus Paenibacillus, for which the name Paenibacillus rhizosphaerae sp. nov. is proposed. The type strain is CECAP06(T) (=LMG 21955(T) = CECT 5831(T)).
Assuntos
Cicer/microbiologia , Bacilos Gram-Positivos Formadores de Endosporo/classificação , Bacilos Gram-Positivos Formadores de Endosporo/isolamento & purificação , Raízes de Plantas/microbiologia , Microbiologia do Solo , Aerobiose , Argentina , Composição de Bases , Metabolismo dos Carboidratos , Catalase/análise , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , DNA Ribossômico/química , DNA Ribossômico/isolamento & purificação , Esculina/metabolismo , Ácidos Graxos/análise , Ácidos Graxos/isolamento & purificação , Genes de RNAr , Violeta Genciana , Bacilos Gram-Positivos Formadores de Endosporo/citologia , Bacilos Gram-Positivos Formadores de Endosporo/fisiologia , Dados de Sequência Molecular , Movimento , Hibridização de Ácido Nucleico , Oxirredutases/análise , Fenazinas , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Esporos Bacterianos , beta-Glucosidase/análiseRESUMO
Fifteen isolates from several nodulated tropical legumes from Puerto Rico (USA) were characterised by their phenotypic, molecular and symbiotic features. The identification of isolates was based on a polyphasic approach, including phenotypic characteristics, 16S rRNA sequencing, Low molecular weight (LMW) RNA profiles, Two Primers-RAPD patterns, and restriction patterns from 16S rDNA molecules. Despite of the variety of hosts included in this study the 15 isolates were separated into only two groups that corresponded to Rhizobium gallicum and Rhizobium tropici. This work shows that R. gallicum and R. tropici nodulate legume plants, such as Sesbania, Caliandra, Poitea, Piptadenia, Neptunia and Mimosa species, that were not previously considered as hosts for these rhizobia. Moreover, some of these host plants can be nodulated by both species. The results confirm the great promiscuity of R. tropici and also support the hypothesis that the species R. gallicum may be native from America or cosmopolitan and worldwide spread.