Abstract: In order to provide an excellent source of fermentation bacteria for engineering production of ectoine, Halomonas sp. XH26 from the Xiao Chaidan Saline lake, was mutated by UV radiation to obtain the mutant strain with high yield of ectoine. Morphological observation, physiological and biochemical test and 16S rRNA gene sequencing were used to determine the classification status of the strain. The positive mutant strain was screened by UV mutagenesis with ectoine yield more than twice that of the original strain, intracellular ectoine production was determined by HPLC, and the mutant strain was subcultured to study the yield stability of ectoine. The experimental results showed that the original strain XH26 (optimal yield of ectoine 456.82 mg/L±15.72 mg/L, CDW 0.71 g/g±0.04 g/g) was treated with 9 rounds of UV mutagenesis, and 7 strains with high-yielding mutant ectoine were obtained, and the yield of ectoine was significantly increased (about 200%). Among them, the strain HU09-32 with the largest accumulation amount had a yield up to 1351.09 mg/L±17.69 mg/L (an increase of 290%), and it was continuously subcultured for 40 days (inoculated for 2 days/time). The intracellular ectoine yield was stable, and the growth characteristics, proliferation speed and accumulation amount were significantly better than the original strain XH26, with good fermentation production and industrial application potential.

Key words:  Halomonas, ectoine, UV mutagenesis, accumulation, mutation breeding