Study on the Fermentation Conditions and Fermentation Products Activity of Endophytic Actinomycetes Hj3 from Rhodiola rosea L.

Purpose In order to explore the new potential biocontrol member Hj3 (Streptomyces variabilis), the fermentation conditions, inhibition mechanism and control efficiency of postharvest tomato early blight of antifungal substance produced by endophytic actinomycetes Hj3 from Rhodiola rosea were studied.

Method Using mycelial growth rate method, the best medium and inoculation dose were screened. The cultivated temperature, rotated speed, the initial pH value were discussed by the orthogonal experimental design. And the growth curve of Hj3, antifungal substance produced curve of Hj3, spore production, spore germination of Alternaria solani affected by fermentation broth of Hj3, and the control efficacy of postharvest tomato early blight were tested.

Results The 8% seed medium of Hj3 was inoculated in the medium with lactose 15 g, corn meal 4 g, K₂HPO₄ 0.8 g, KCl 0.2 g, CaCO₄ 1.6 g, water 1 000 mL, pH 7. It was incubated in 28 ℃ and shaken with 150 r/min. In the fourth day the viable count was up to maximum, and the inhibition rate of Hj3 fermentation broth was the highest in the fifth day. The antifungal substance of Hj3 could inhibit the spore production and spore germination of A. solaniobviously, and control the postharvest tomato early blight well.

Conclusion The fermented condition avails the further study and application of antifungal substance produced by Hj3. And the inhibition mechanism and control efficacy of postharvest tomato early blight could support theoretically for practical application of Hj3.