Natronogracilivirga saccharolytica gen. nov., sp. nov. and Cyclonatronum proteinivorum gen. nov., sp. nov., haloalkaliphilic organotrophic bacteroidetes from hypersaline soda lakes forming a new family Cyclonatronaceae fam. nov. in the order Balneolales

Two heterotrophic bacteroidetes strains were isolated as satellites from autotrophic enrichments inoculated with samples from hypersaline soda lakes in southwestern Siberia. Strain Z-1702T is an obligate anaerobic fer-mentative saccharolytic bacterium from an iron-reducing enrichment culture, while Ca. Cyclonatronum pro-teinivorum OmegaT is an obligate aerobic proteolytic microorganism from a cyanobacterial enrichment. Cells of isolated bacteria are characterized by highly variable morphology. Both strains are chloride -independent moderate salt-tolerant obligate alkaliphiles and mesophiles. Strain Z-1702T ferments glucose, mal-tose, fructose, mannose, sorbose, galactose, cellobiose, N-acetyl-glucosamine and alpha-glucans, including starch, glycogen, dextrin, and pullulan. Strain OmegaT is strictly proteolytic utilizing a range of proteins and peptones. The main polar lipid fatty acid in both strains is iso-C15:0, while other major components are various C16 and C17 isomers. According to pairwise sequence alignments using BLAST Gracilimonas was the nearest cul-tured relative to both strains (<90% of 16S rRNA gene sequence identity). Phylogenetic analysis placed strain Z-1702T and strain OmegaT as two different genera in a deep-branching clade of the new family level within the order Balneolales with genus. Based on physiological characteristics and phylogenetic position of strain Z -1702T it was proposed to represent a novel genus and species Natronogracilivirga saccharolityca gen. nov., sp. nov. (= DSMZ 109061T =JCM 32930T =VKM B 3262T). Furthermore, phylogenetic and phenotypic param-eters of N. saccharolityca and C. proteinivorum gen. nov., sp. nov., strain OmegaT (=JCM 31662T, =UNIQEM U979T), make it possible to include them into a new family with a proposed designation Cyclonatronaceae fam. nov..

Automated summary

Two heterotrophic bacteroidetes strains were isolated from hypersaline soda lakes in southwestern Siberia. Strain Z-1702T is an obligate anaerobic fermentative saccharolytic bacterium, while Ca. Cyclonatronum proteinivorum OmegaT is an obligate aerobic proteolytic microorganism. Both strains have highly variable morphology and are chloride-independent moderate salt-tolerant obligate alkaliphiles and mesophiles.