Study on antifungal activity of hyphae extract of a streptomyces strain HU2014 against four phytopathogenic fungi

Abstract

The application of chemical pesticides emerges many disadvantages, so new natural resources of suppressing plant diseases are needed. Actinobacteria are gaining interest in agriculture as biological control agents (BCAs). Streptomyces spp. are part of actinobacteria and are known for producing a large number of active metabolites. In this paper, the antifungal effect of the hyphae methanol extract (HME) of a Streptomyces strain HU2014 on four phytopathogenic fungi was investigated by the growth rate method. A pretest study on different concentrations of the HME was conducted to determine a suitable range of antifungal activity. The result showed that the inhibited effect of the HME against Rhizoctonia solani was better than the other three fungi, reached 100 % with the concentration of 0.5 mg/ml. Based on the above test, the Log concentrationprobit regression lines were obtained according to the inhibition rate with different concentrations. The EC50 value of the HME against R. solani at 48 h, 72 h, and 96 h were lowest in other fungi respectively. The toxicity regression equations of HME on R. solani was y = 6.9826+1.4028x (Correlation Coefficient r = 0.9783), and the EC50 value was 0.0386 mg/ml at 72 h. The toxicity regression equations of HME on Botrytis cinerea was y=5.6627+1.2386x (Correlation Coefficient r = 0.9614), and the EC50 value was 0.2917 mg/ml at 72h. The toxicity regression equations of HME on Colletotrichum gloeosporioides was y = 5.3143 + 1.0873x (Correlation Coefficient r=0.9996), and the EC50 value was 0.5140 mg/ml at 72 h. The toxicity regression equations of HME on Fusarium graminearum was y = 5.7011 + 2.3280x (Correlation Coefficient r = 0.9869), and the EC50 value was 0.5024 mg/ml at 72 h. The Streptomyces HU2014 strain has a significant antifungal effect and may become a new biocontrol agent in agricultural production.