Antifungal effect of volatile organic compounds produced by Streptomyces salmonis PSRDC‐09 against anthracnose pathogen Colletotrichum gloeosporioides PSU‐03 in postharvest chili fruit.

Aims: Application of volatile organic compounds (VOCs) from Streptomyces salmonis PSRDC‐09 (VOCs PSRDC‐09) grown on sterile wheat seeds against chili anthracnose pathogen was investigated in vitro and in vivo. Methods and Results: Among 10 isolates of Colletotrichum species tested, Colletotrichum gloeosporioides PSU‐03 was selected as the most aggressive anthracnose pathogenic strain on chili fruit against VOCs produced by Streptomyces species. Among 11 isolates, the strain PSRDC‐09 exhibited the highest antifungal activity and was identified as S. salmonis PSRDC‐09. The antagonistic mechanism of the VOCs PSRDC‐09 on morphological of C. gloeosporioides PSU‐03, observed by scanning electron microscope (SEM), revealed the irregular distortions in the fungal hyphae. The effect of inoculum size and spore concentration of S. salmonis PSRDC‐09 prepared as a wheat seed inoculum on the suppression of C. gloeosporioides PSU‐03 was studied both in vitro and on chili fruit. The optimum inoculum size (45 g 0·31 l−1) and spore concentration (107 spores per ml) of the wheat seed culture of S. salmonis PSRDC‐09 exhibited the complete suppression (100% inhibition) on C. gloeosporioides PSU‐03. The optimum fumigation period of the VOCs PSRDC‐09 (45 g 1·38 l−1) was found to be 24 h. Based on gas chromatography‐mass spectrometry (GC‐MS) analysis, 14 major VOCs (produced by the strain PSRDC‐09) were detected and l‐linalool was the main volatile component. Conclusions: The results indicated that the VOCs from S. salmonis PSRDC‐09 could effectively control the chili anthracnose disease caused by C. gloeosporioides. Significance and Impact of the Study: These findings suggest that S. salmonis PSRDC‐09 may have the potential to become a promising biofumigant for biocontrol of chili anthracnose disease in the postharvest system. [ABSTRACT FROM AUTHOR]