Studying on the antifungal activity of the actinomycete XK1 isolated from growing orange’s soil against pathogenic fungi causing disease in citrus.

Abstract

Streptomyces are considered to be one of the actinomycetes genera having potential in the production of agricultural probiotics because they are safe and have strong antagonism to many bacterial and fungal species that cause plant diseases. In this study, 18 strains of actinomycetes were isolated from growing oranges’ soil in Ha Giang province, of which the actinomycete strain XK1 was considered to be strongly resistant to the fungi Penicillium digitatum and Colletotrichum gloeosporioides causing fruit rot and shedding in citrus. Based on morphological characteristics and 16S rRNA sequence, the strain XK1 was determined to belong to the Streptomyces albulus. On MT2 medium with pH=6, after five days of shaking cultivation at 30°C, the liquid cultures of S. albulus XK1 showed the strongest resisting activity to P. digitatum and C. gloeosporioides. At the same time, the broth cultures of S. albulus XK1 showed inhibitory activity against P. digitatum in oranges. The actinomycete strain S. albulus XK1 was selected base on strong antifungal ability against P. digitatum and C. gloeosporioides and had a potential for application in the production of probiotics used to control fruit rot and shedding in citrus.