RESUMEN
A novel actinomycete, strain S10(T), was isolated from rhizosphere soil of wild Vitis vinifera in Thinghir, Ouarzazate Province, Southern Morocco. The taxonomic status of this strain was established using a polyphasic approach. Strain S10(T) had white-grey aerial mycelium with long, spiral spore chains bearing smooth surfaced spores and produced a yellow diffusible pigment. Chemotaxonomic analyses showed that the cell wall of strain S10(T) contained ll-diaminopimelic acid and glycine. Phylogenetic analysis based on the almost complete 16S rRNA gene sequence indicated that strain S10(T) belonged to the Group I streptomycetes, branching off next to Streptomyces marokkonensis LMG 23016(T) from the Streptomyces violaceoruber group. DNA-DNA relatedness and phenotypic data distinguished strain S10(T) from the phylogenetically closest related type strains. It is therefore proposed that strain S10(T) (=CCMM B35(T)=DSM 41919(T)) represents the type strain of a novel species of the genus Streptomyces, for which the name Streptomyces thinghirensis sp. nov. is proposed.
Asunto(s)
Microbiología del Suelo , Streptomyces/clasificación , Streptomyces/aislamiento & purificación , Vitis , ADN Bacteriano/genética , ADN Ribosómico/genética , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Streptomyces/genéticaRESUMEN
A Gram-negative, non-sporulating, rod-shaped, motile bacterium, with a single polar flagellum, designated strain PsJN(T), was isolated from surface-sterilized onion roots. This isolate proved to be a highly effective plant-beneficial bacterium, and was able to establish rhizosphere and endophytic populations associated with various plants. Seven related strains were recovered from Dutch soils. Based on 16S rRNA gene sequence data, strain PsJN(T) and the Dutch strains were identified as representing a member of the genus Burkholderia, as they were closely related to Burkholderia fungorum (98.7 %) and Burkholderia phenazinium (98.5 %). Analysis of whole-cell protein profiles and DNA-DNA hybridization experiments confirmed that all eight strains belonged to a single species. Strain PsJN(T) had a DNA G+C content of 61.0 mol%. Only low levels of DNA-DNA hybridization to closely related species were found. Qualitative and quantitative differences in fatty acid composition between strain PsJN(T) and closely related species were identified. The predominant fatty acids in strain PsJN(T) were 16 : 0, 18 : 1omega7c and summed feature 3 (comprising 16 : 1omega7c and/or iso-15 : 0 2-OH). Isolate PsJN(T) showed high 1-aminocyclopropane-1-carboxylate deaminase activity and is therefore able to lower the ethylene level in a developing or stressed plant. Production of the quorum-sensing signal compound 3-hydroxy-C8-homoserine lactone was detected. Based on the results of this polyphasic taxonomic study, strain PsJN(T) and the seven Dutch isolates are considered to represent a single, novel species, for which the name Burkholderia phytofirmans sp. nov. is proposed. The type strain is strain PsJN(T) (=LMG 22146(T) = CCUG 49060(T)).