关键词: 果树, 内生细菌, 分离, 筛选, 菌株鉴定, 抑制作用

Abstract: Two hundred and thirty-five endophytic bacteria were isolated from the xylem from diverse healthy fruit trees with tissue isolation method. Through the primary and secondary screening with confront-culture method，six antagonistic strains were obtained. Antibacterial spectrum tests were performed with bacteria fermentation broth get by autoclaving and filtration. Ultimately，fermentation broth from strain X8 was found to have high antifungal activities. So strain X8 was further studied on colonization，identification and control. The results showed that：Strain X8 could colonize in apricots，peppers，and so on. The inhibition of fermentation broth from strain X8 was the strongest against Phytophthora capsici，up to 80.3%；Which was above 75% against three Alternaria pathogens. The control effect of X8 fermentation broth to tomato gray mould and pepper phytophthora blight reached 75.4% and 79.3%，which were significantly higher than those of 50% procymidone and 25% metalaxyl. With the 16S rDNA sequence analysis，strain X8 shared 99% homology with Bacillus subtilis. According to morphology，physiological and biochemical characters as well as 16S rDNA sequences，strain X8 was identified as B. subtilis（GenBank accession number HQ647257）.

Key words: fruit tree, endophytes, isolation, screening, strain identification, inhibition