Abstract: To enhance the production of ε-poly-L-lysine (ε-PL) by Streptomyces albluus, we mutagenized this strain by sequential treatment with atmospheric and room temperature plasma and diethyl sulfate (ARTP-DES). The optimized treatment conditions were determined as follows: ARTP power 110 W, exposure distance 2 mm, mutagenesis time 30, 60, and 105 s, DES concentration 0.6% (V/V), and reaction time 20 min. A rapid screening method was established by streptomycin resistance combined with methylene blue transparent circles. ε-PL content was determined by enzyme-linked immunosorbent assay (ELISA) with a 48-well microplate. The results showed that the positive mutation rate for streptomycin resistance was up to 40.8%. Furthermore, one strain designated AD-9 with good genetic stability was selected. It produced 2.1 g/L ε-PL in shake-flask fermentation, which was 2.1 times as high as that produced by the parent strain. Studies of the physiological characteristics indicated that the mutant strain AD-9 showed changes in nutritional requirements, pellet morphology and nutrient consumption during fermentation. This study indicates that continuous ARTP-DES mutagenesis is an efficient breeding method for increased production of ε-PL.

Key words: Streptomyces albluus; ε-poly-L-lysine; continuous mutation; rapid?screening; physiological properties