Abstract:The optimum conditions for preparation and regeneration of Rhizopus chinensis LN-A protoplasts were obtained after studying the effects of different factors on them, such as the enzyme composition, concentration and reaction time as well as the different growth phase of the strains. After treating the strains in log phase with concentration of 5 mg/mL snail enzyme, 5 mg/mL cellulose enzyme, 2 mg/mL lysozyme for 2 hours under 30°C, the protoplast formation was up to 5.8×107 and regeneration reached 5.7%. On the basis of this, irradiation of He-Ne laser (λ = 632.8 nm, power = 15 mW) for 20 minutes and UV for 150 seconds were performed on the protoplasts of Rhizopus chinensis LN-A. The mutant LN-B was obtained and the final gastrodin yield was up to 28.9%, which was 20% higher than LN-A.