Actinomycetospora soli sp. nov., isolated from the rhizosphere soil of Averrhoa carambola L

A novel actinobacterium, designated strain SF1(T), was isolated from the rhizosphere soil of a star fruit plant (Averrhoa carambola L.) collected from Bangkok, Thailand, and its taxonomic position was evaluated. The strain showed morphological, chemotaxonomic and phylogenetic characteristics consistent with its classification in the genus Actinomycetospora. Strain SF1(T) was an aerobic, Gram-stain-positive and non-motile actinobacterium. Growth occurred at 15-35 degrees C, at pH 4.0-12.0 and in the presence of 0-10% (w/v) NaCl. The 16S rRNA gene sequence of strain SF1(T) showed the highest similarity to Actinomycetospora chiangmaiensis YIM 0006(T) (99.5 %), Actinomycetospora corticicola 014-5(T) (98.8%) and Actinomycetospora endophytica A-T 8314(T) (98.8%). The genome sequencing revealed a genome size of 6.52 Mbp and a DNA G+C content of 74.0 %. In addition, the average nucleotide identity values between strain SF1(T) and reference strains, A. chiangmaiensis DSM 45062(T), A. corticicola DSM 45772(T) and A. endophytica TBRC 5722(T), were found to be 86.1, 86.5 and 79.7%, respectively, and the level of digital DNA-DNA hybridization between them were 32.4, 32.4 and 23.3 %, respectively. The whole-cell hydrolysates of strain SF1(T) contained meso-diaminopimelic acid as the diagnostic diamino acid, with arabinose, galactose, glucose and ribose as whole-cell sugars. The predominant menaquinone was MK-8(H-4). Major cellular fatty acids were iso-C-16:0 and a summed feature consisting of C-16:1 omega 6c/C-16:1 omega 7c. Characterization based on chemotaxonomic, phylogenetic, phenotypic and genomic evidence demonstrated that strain SF1(T) represents a novel species of the genus Actinomycetospora, for which the name Actinomycetospora soli sp. nov. is proposed. The type strain is strain SF1(T) (=TBRC 15166(T)= NBRC 115295(T)).

Automated summary

A novel actinobacterium strain SF1(T) was isolated from the rhizosphere soil of a star fruit plant in Bangkok, Thailand. Through morphological, chemotaxonomic, and phylogenetic analysis, it was classified in the genus Actinomycetospora. The strain showed aerobic, Gram-positive, and non-motile characteristics, with growth occurring in a wide range of temperature, pH, and salt concentrations. The 16S rRNA gene sequence of strain SF1(T) had high similarity to other Actinomycetospora strains. Genome sequencing revealed the size and G+C content of the strain's genome. Based on chemotaxonomic, phylogenetic, phenotypic, and genomic evidence, strain SF1(T) represents a novel species in the genus Actinomycetospora.