Genetic diversity of glacier-inhabiting Cryobacterium bacteria in China and description of Cryobacterium zongtaii sp. nov. and Arthrobacter glacialis sp. nov.

Cryobacterium and Arthrobacter are members of Actinobacteria, and are often found in cold environments. In this study, 48 Cryobacterium strains, including 9 type strains and 39 new isolates collected from glaciers in China were subjected to multilocus sequence analysis (MLSA). Phylogenetic analysis revealed that Cryobacterium comprised four cold-adapted clusters. Also, 19 potential novel Cryobacterium species were found using 0.065 as the cut-off point of genetic distance between the concatenated gene sequences. Additionally, three Cryobacterium strains (TMN-42T , TMN-39-1 and TMB1-8) and two Arthrobacter strains (HLT2-12-2T , TMN-18) isolated from glaciers were subjected to taxonomic analysis. Based on 16S rRNA gene sequences, MLSA data and average nucleotide identity (ANI) values, they represented a novel Cryobacterium species and a novel Arthrobacter species. Specifically, strain TMN-42T was most closely related to the type strains of Cryobacterium arcticum and Cryobacterium psychrotolerans with 83.79% and 77.78% ANI values, respectively. The ANI values between strain HLT2-12-2T and its closely relatives Arthrobacter psychrochitiniphilus GP3T and Arthrobacter alpinus S6-3T were 76.66% and 77.94%, respectively. Therefore, we propose two novel species, Cryobacterium zongtaii sp. nov. (TMN-42T =CGMCC 1.9695T =NBRC 111591T ) and Arthrobacter glacialis sp. nov. (HLT2-12-2T =CGMCC 1.10025T =NBRC 113092T ).