Abstract: 【Objective】 The paper aimed at investigating the stability and potential application of the antifungal substance in the cell-free liquid culture of Actinomycete CCTCC M207210. 【Method】 The antifungal ability of the cell-free liquid culture of Actinomycete CCTCC M207210 was tested on agar media after pretreatment of heat, acid, alkali, and ultraviolet radiation. The cell-free liquid culture was added into apple juice medium and sprayed on apple surface after inoculation of patulin-producing Penicillium expansum SP2204 and SP2205. After a period of cultivation of 12 d, 7 d respectively, the diameter of rotten spot in apple was measured and patulin production in the apple juice culture was tested to evaluate the inhibitory ability of the cell-free culture in practical application. 【Result】 Heating, acidic and alkaline treatment, and ultraviolet radiation could destroy, to some extent, the antifungal activity of the cell-free liquid culture of Actinomycete CCTCC M207210. The antifungal activity was completely destroyed when the cell-free liquid culture was pretreated at 100℃ for 60 min or subjected to ultraviolet radiation (30 W, 245 nm, 15 cm distance) for 90 min. The liquid culture showed the most stable antifungal activity at the original pH (5.7) and more stable at a little alkaline pH than acidic condition. Extension rate of the rotten spots was reduced by 25% when the liquid culture was sprayed on the apple surface 120 h after the inoculation of P. expansum. Patulin production was reduced by 90% when the liquid culture was added in the apple juice cultivation of P.expansum in ratio of 40% (v/v). 【Conclusion】 The antifungal substance in the cell-free liquid culture of Actinomycete CCTCC M207210 showed high resistibility to heat, acidic and alkaline conditions, and ultraviolet radiation, and had great potential in application of inhibiting the growth and patulin production of P. expansum for apple storage and apple juice production.

Key words: apple, patulin, Actinomycete CCTCC M207210, antifungal activity, stability