Psychrobacter cryohalolentis sp. nov. and Psychrobacter arcticus sp. nov., isolated from Siberian permafrost

1 Center for Microbial Ecology and NASA Astrobiology Institute, Michigan State University, East Lansing, MI 48824, USA 2 Department of Biology, University of Puerto Rico at Humacao, Humacao, PR 00791, Puerto Rico 3 Department of Food Science, North Carolina State University, Raleigh, NC 27695, USA 4 Institute of Physico-chemical and Biological Problems in Soil Science, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russian Federation Correspondence Corien Bakermans bakerm16{at}msu.edu Three Gram-negative, non-motile, non-pigmented, oxidase-positive coccobacilli capable of growth at temperatures from –10 to 30 °C and salinities of 0 to 1.7 M NaCl were isolated from Siberian permafrost and characterized. Both 16S rRNA and gyrB gene sequencing studies placed the isolates in the Gammaproteobacteria within the genus Psychrobacter . However, with higher bootstrap values and reproducible tree topologies, gyrB represented a more reliable phylogenetic marker for the taxonomy of Psychrobacter species. DNA–DNA hybridization data supported gyrB tree topologies and established two relatedness groups within the three isolates; neither of these groups was related at the species level to any previously described Psychrobacter species. The two groups of isolates could be differentiated phenotypically from 13 previously described Psychrobacter species using API strips. These results support the existence of two novel species of Psychrobacter , for which we propose the names Psychrobacter cryohalolentis sp. nov. (type strain K5 T =DSM 17306 T =VKM B-2378 T ) and Psychrobacter arcticus sp. nov. (type strain 273-4 T =DSM 17307 T =VKM B-2377 T ). Abbreviations: ANI, average nucleotide identity; PLFA, phospholipid fatty acid The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of isolates K5 T , 237-4 T and 215-51 are AY660685 , AY444822 and AY444823 , and those for the gyrB sequences obtained in this study are DQ143914 –DQ143928 and CP000082 .