Abstract: Dimethylsulfoniopropionate (DMSP) is a highly abundant sulfur-containing compound in marine environments. It is mainly produced by marine phytoplankton, and can act as a key nutrient for marine microorganisms. Strain DMSP-1 was isolated from Arctic seawater of Kongsfjorden using a selective growth medium. Based on the 16SrRNA gene sequence and genomic ANI (Average Nucleotide Identity) analyses, the bacterium was classified and identified as the species Pseudomonas lactis. The bacterial cells were rods with polar flagella. The strain was psychrotrophic (growing well between 22 and 29°C with an upper temperature limit at 38°C) and halotrophic (growing well between 0 and 4% NaCl with an upper salinity limit at 8% NaCl), indicating adaptation to the local habitat. A carbon source for growth experiment confirmed that strain DMSP-1 could grow with DMSP as the sole carbon source. The bacterium showed many genotypic characteristics similar to the type strain Pseudomonas lactis WS 4992^T. At the same time, in contrast with P. lactis WS 4992^T, strain DMSP-1 showed tryptophan deaminase and urease activity, and was unable to produce acid from rhamnose. Further research on Pseudomonas sp. DMSP-1 will provide deep insight into the mechanism of marine bacteria degrading DMSP and their ecological functions in the Arctic marine environment.

Key words: Arctic, Kongsfjorden, Pseudomonas, DMSP degradation