Abstract: Bacillus subtilis OST23a, a marine bacterium, was mutagenized with both UV light and DES treatment to obtain a high-yield antioxidant exopolysaccharide (EPS)-producing strain named as UD292. The EPS yield of the mutant strain was 43.92 mg/L, which increased 6.26-fold as compared with the original strain. The EPS obtained from both strains showed no obvious difference in their antioxidant activity. The mutant strain remained stable in successive passages.

Key words: antioxidant exopolysaccharide, marine bacteria, mutation screening