Abstract: In this study, 15 strains of endophytic bacteria were isolated from healthy Dangshan pear. Out of these, one isolate, designated DSL-9, was screened for its strong inhibitory activity against Colletotrichum gloeosporioides. This strain was tentatively identified as Bacillus subtilis based on its morphological characteristics and 16S rDNA sequence. The results showed that the antifungal effect of strain DSL-9 was mediated mainly by the extracellular compounds secreted by it. A crude protein extract from DSL-9 was obtained by ammonium sulfate precipitation. The antifungal activity of the extract was not significantly changed at 30–60 ℃ but was decreased at temperatures higher than 60 ℃. In the pH range of 7 to 10, high antifungal activity was obtained without significant changes. Ultraviolet (UV) light had no significant influence on the antifungal extract. After protease treatment, the antifungal activity was declined. DSL-9 could improve resistance to C. gloeosporioides in Dangshan pear as reflected by its effect on defense enzyme activities in infected pear fruits. B. subtilis DSL-9 will have potential application in biological control of C. gloeosporioides in Dangshan pear.

Key words: Dangshan pear, endophytic bacteria, Colletotrichum gloeosporioides, defense enzymes