Proposal of Crystallibacter gen. nov., Crystallibacter permensis sp. nov. and Crystallibacter degradans sp. nov. for the salt-tolerant and aromatics degrading actinobacteria, and reclassification of Arthrobacter crystallopoietes as Crystallibacter crystallifaciens comb. nov.

Four salt-tolerant and aromatics degrading strains used in this study were isolated from polluted technogenic soil on the territory of the Verkhnekamsk potash deposit (Russia). The strains were aerobic, Gram-stain-positive, non-motile, non-endospore-forming irregular rods, exhibiting a marked rod-coccus growth cycle. They contained lysine-based peptidoglycan, teichulosonic acid and poly(glycosyl phosphate) polymers in the cell walls. The major menaquinone was MK-9(H), the predominant fatty acids were saturated, anteiso- and iso-branched, and the major compounds of polar lipid profiles included phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and two glycolipids (monogalactosyldiacylglycerol and dimannosylglyceride). The strains showed the highest 16S rRNA gene sequence similarity to Arthrobacter crystallopoietes (99.6-99.9%), followed by A. mangrovi (98.3-98.5%) and A. globiformis, the type species of the genus Arthrobacter (97.6-97.8%). The values of overall genome related indices (ANI, dDDH, AAI and POCP) indicated that the target strains and A. crystallopoietes represented three species within a new genus. These species clearly differed from each other and from A. mangrovi and A. globiformis in the phenotypic traits, including the peptidoglycan type and the structures and compositions of cell wall glycopolymers. Based on the findings of this study and the previously published data, we provide the description of the new genus Crystallibacter gen. nov. with the type species Crystallibacter crystallifaciens comb. nov. (type strain, VKM Ac-1107) and two newly revealed species, Crystallibacter permensis sp. nov. (type strain, B905 = VKM Ac-2550 = LMG 33113) and Crystallibacter degradans sp. nov. (type strain, SF27 = VKM Ac-2063 = LMG 33112).