Minicystis rosea gen. nov., sp. nov., a polyunsaturated fatty acid-rich and steroid-producing soil myxobacterium

A bacterial strain designated SBNa008^T was isolated from a Philippine soil sample. It exhibited the general characteristics associated with myxobacteria, such as swarming of Gram-negative vegetative rod cells, fruiting body and myxospore formation and predatory behaviour in lysing micro-organisms. The novel strain was characterized as mesophilic, chemoheterotrophic and aerobic. The major fatty acids were C_20 : 4ω6,9,12,15 all cis (arachidonic acid), iso-C_15 : 0, C_17 : 1 2-OH and iso-C_15 : 0 dimethylacetal. Interestingly, SBNa008^T contained diverse fatty acids belonging to the commercially valuable polyunsaturated omega-6 and omega-3 families, and a highly conjugated dihydroxylated C₂₈ steroid. The G+C content of the genomic DNA was 67.3 mol%. The 16S rRNA gene sequence revealed 95–96 % similarity to sequences derived from clones of uncultured bacteria and 94–95 % similarity to cultured members of the suborder Sorangiineae. Phylogenetic analysis revealed that strain SBNa008^T formed a novel lineage in the suborder Sorangiineae. Based on a polyphasic taxonomic characterization, we propose that strain SBNa008^T represents a novel genus and species, Minicystis rosea gen. nov., sp. nov. The type strain of Minicystis rosea is SBNa008^T ( = DSM 24000^T = NCCB 100349^T).