A new aerobic alphaproteobacterium, strain SA-279T, was isolated from a water sample of a crater lake. The 16S rRNA gene sequence analysis revealed that strain SA-279T formed a distinct lineage within the family Ancalomicrobiaceae and shared the highest pairwise similarity values with Pinisolibacterravus E9T (96.4 %) and Ancalomicrobiumadetum NBRC 102456T (94.2 %). Cells of strain SA-279T were rod-shaped, motile, oxidase and catalase positive, and capable of forming rosettes. Its predominant fatty acids were C18 : 1ω7c (69.0 %) and C16 : 1ω7c (22.7 %), the major respiratory quinone was Q-10, and the main polar lipids were phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, phosphatidylglycerol, an unidentified aminophospholipid and an unidentified lipid. The G+C content of the genomic DNA of strain SA-279T was 69.2 mol%. On the basis of the phenotypic, chemotaxonomic and molecular data, strain SA-279T is considered to represent a new genus and species within the family Ancalomicrobiaceae, for which the name Siculibacillus lacustris gen. nov., sp. nov. is proposed. The type strain is SA-279T (=DSM 29840T=JCM 31761T).
Keywords: Alphaproteobacteria; Ancalomicrobiaceae; new genus; rosette.