Quadrisphaera setariae sp. nov., polyphosphate-accumulating bacterium occurring as tetrad or aggregate cocci and isolated from Setaria viridis

Abstract

A Gram-stain-positive, orange-pigmented, aerobic, cocci (occurring in tetrads), non-spore-forming, non-motile bacterium, designated as DD2A(T), was isolated from Setaria viridis collected at Dongguk University, Republic of Korea. Phylogenetic analysis based on the 16S rRNA gene revealed that strain DD2A(T) was most closely related to type strains of the genus Quadrisphaera. Strain DD2A(T) showed the highest 16S rRNA gene sequence similarities to Quadrisphaera oryzae TBRC 8486(T) (99.4%) and Quadrisphaera granulorum JCM 16010(T) (98.8%). Strain DD2A(T) also showed auto-aggregation ability. The digital DNA-DNA hybridization values between strain DD2A(T) and the reference strains, Q. oryzae TBRC 8486(T) and Q. granulorum JCM 16010(T) were 31.1 and 27.4%, respectively. The average nucleotide identity values between strain DD2A(T) and Q. oryzae TBRC 8486(T) and Q. granulorum JCM 16010(T) were 86.3 and 84.1 %, respectively. The major polar lipids of strain DD2A(T) were diphosphatidylglycerol and phosphatidylglycerol. The major cellular fatty acid of strain DD2A(T) was anteiso-C-15:0. The cell-wall peptidoglycan contained mesodiaminopimelic acid (which is a diagnostic cell-wall diamino acid), alanine and glutamic acid. The respiratory quinones was found to be menaquinone-8. The DNA G+C content of strain DD2A(T) was 74.8 mol%. On the basis of the findings of genotypic, phenotypic, chemotaxonomic and phylogenetic analyses, strain DD2A(T) was considered to represent a novel member in the genus Quadrisphaera, for which the name Quadrisphaera setariae sp. nov. is proposed. The type strain of Quadrisphaera setariae is DD2A(T) (=KACC 21165(T)=NBRC 113770(T)).