RESUMEN
Two rhizobial strains, BSA136T and BSA150, related to the genus Mesorhizobium were isolated from root nodules of Lotus tenuis grown in saline-alkaline lowlands soil from Argentina. These strains showed different repetitive element palindromic PCR fingerprinting patterns but shared more than 99â% sequence similarity for both 16S rRNA and recA genes. Despite the symbiotic nodC gene sequences of our strains being related to the canonical Lotus biovar species comprising Mesorhizobium loti and Mesorhizobium japonicum, the 16S rRNA phylogenetic marker suggests that their taxonomical identities are closely related to Mesorhizobium helmanticense, Mesorhizobium metallidurans, Mesorhizobium thianshanense, Mesorhizobium gobiense and Mesorhizobium tarimense. Multilocus sequence analysis performed with seven housekeeping genes confirmed that BSA136T belongs to a separate clade within the genus Mesorhizobium. The results of comparisons for in silico DNA-DNA hybridization and average nucleotide identity indexes between the genomes of BSA136T and closest-related Mesorhizobium species were below the threshold for species delineation. Phenotypic features differentiated BSA136T from its closest-related species. On the basis of our results, BSA136T and BSA150 can be considered to represent a novel species of the genus Mesorhizobium, for which the name Mesorhizobium sanjuanii sp. nov. is hereby proposed. The type strain of this species is BSA136T (=CECT 9305T=LMG 30060T), for which the draft genome sequence is available.
Asunto(s)
Lotus/microbiología , Mesorhizobium/clasificación , Filogenia , Nódulos de las Raíces de las Plantas/microbiología , Argentina , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/química , Mesorhizobium/genética , Mesorhizobium/aislamiento & purificación , Tipificación de Secuencias Multilocus , Hibridación de Ácido Nucleico , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
AIMS: To isolate and characterize phosphate-solubilizing strains from a constrained environment such as the Salado River Basin and to assess their phosphate-solubilizing mechanisms, to further selection of the most promising strains to inoculate and improve the implantation and persistence of Lotus tenuis in the most important area devoted to meat-cow production in Argentina. METHODS AND RESULTS: Fifty isolates were obtained and through BOX-PCR analysis, 17 non-redundant strains were identified. Subsequently, they were found to be related to Pantoea, Erwinia, Pseudomonas, Rhizobium and Enterobacter genera, via 16S rRNA gene sequence analysis. This was in agreement with the clusters obtained by antibiotic resistance analysis. All isolates were tested for their phosphate-solubilizing activity and selected strains were inoculated onto L. tenuis plants. The most efficient isolate, was identified as Pantoea eucalypti, a novel species in terms of plant growth-promoting rhizobacteria. CONCLUSIONS: The isolates obtained in this study showed a significant in vitro plant-growth promoting activity onto Lotus tenuis and the best of them solubilizes phosphate mainly via induction of the metabolism through secretion and oxidation of gluconic acid. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of these bacteria as bioinoculants, alone or in combination with nitrogen-fixing micro-organisms, could be a sustainable practice to facilitate the nutrient supply to Lotus tenuis plants and preventing negative side-effects such as eutrophication.
Asunto(s)
Lotus/crecimiento & desarrollo , Lotus/microbiología , Pantoea/fisiología , Fosfatos/metabolismo , Rizosfera , Microbiología del Suelo , Argentina , Deshidrogenasas de Carbohidratos/metabolismo , Enterobacter/genética , Erwinia/genética , Eucalyptus/metabolismo , Gluconatos/metabolismo , Glucosa Deshidrogenasas/metabolismo , Oxidación-Reducción , Pantoea/genética , Pantoea/aislamiento & purificación , Filogenia , Pseudomonas/genética , ARN Ribosómico 16S/genética , Rhizobium/genética , RíosRESUMEN
Cheese whey (CW)-based growth medium efficiently protects Rhizobium loti cells during freezing and desiccation and can maintain their growth in a manner similar to that of traditional mannitol-based medium (YEM). The cheese-whey-based medium (CW) improved viability when used to re-suspend cell pellets kept at -20 degrees C and -80 degrees C and resulted in the survival of over 90% of the cells. Moreover, bacterial pellets obtained from cells grown in CW withstand desiccation better than cells grown in YEM. Survival was over 60% after 30 days at 4 degrees C. No differences were observed in nodulation efficiency between YEM-grown and CW-grown cells. Fast protein liquid chromatography (FPLC) protocols are presented for total protein profile analyses of sweet and acid cheese whey.
Asunto(s)
Queso/microbiología , Microbiología de Alimentos , Proteínas de la Leche/metabolismo , Rhizobium/crecimiento & desarrollo , Queso/análisis , Desecación , Fermentación , Lotus/microbiología , Proteínas de la Leche/análisis , Proteínas de la Leche/química , Rhizobium/fisiología , Proteína de Suero de LecheRESUMEN
Thirty indigenous rhizobia strains, isolated from Lotus tenuis in the area of Chascomús and other regions of the Salado River Basin (Argentina), were characterized based on generation time, acid production, carbon utilization, protein profile, and molecular characterization by restriction fragment length polymorphism (RFLP) analysis of 16S rRNA genes amplified by the polymerase chain reaction (PCR). The results indicated that native rhizobia isolates from the Chascomús area are predominantly fast and intermediate-growers. The unclassified rhizobia examined by PCR-RFLP were found to be closely related to the reference strains of validly described Rhizobium species.
Asunto(s)
Lotus/microbiología , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Rhizobium/clasificación , Rhizobium/genética , Microbiología del Suelo , Argentina , Proteínas Bacterianas/química , ADN Bacteriano/análisis , Genes de ARNr , ARN Ribosómico 16S/genética , Rhizobium/crecimiento & desarrollo , Rhizobium/aislamiento & purificación , SimbiosisRESUMEN
3,4,5-Trisubstituted isoxazolines (2) and isoxazoles (3) were prepared and evaluated for their in vitro and in vivo antithrombotic efficacy. They were compared to 3,5,5-trisubstituted isoxazolines (1) for Factor Xa selectivity and potency. They were also compared in an arterio-venous (A-V) shunt model of thrombosis.