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(20:4)ω6,9,12,15 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)).