从国内16个省市自治区的果园梨果上和土样中分离筛选到对由链格孢霉Alternaria alternate (Fr.) Keissler引起的梨采后黑斑病有明显抑制效果的拮抗菌J18，经生理生化及分子生物学鉴定为枯草芽孢杆菌(Bacillus subtilis)。梨果在拮抗菌J18菌悬液中浸果30 s，晾干后喷施接种病原真菌链格孢霉，处理后梨黑斑病的发病率仅为16.57%，且能在梨果上很好的定殖；将其分别与其他生防因子CaCl2，水杨酸(Salicylic acid, SA)，壳聚糖(Chitosan)复配后，可减低拮抗菌的使用浓度，显著提高生物拮抗菌的拮抗效果，其中与2% CaCl2和1%壳聚糖复配后的拮抗菌悬液其防效分别为72.81%和77.07%，具有很好的应用前景。

A bacterial strain with a high ability of inhibiting alternaria rot disease on pear was isolated from the pear fruits and orchard soil collected from different area across China with in vitro and in vivo methods. By morphological observation, physiological and biochemical characterization and the analysis of the 16S rDNA sequence, this strain was identified as Bacillus subtilis J18. Pretreatment with 108 CFU/mL cell suspension of B. subtilis J18 for 30s could decrease the incidence of alternaria rot on pear to 16.6% after inoculation with pathogenic fungi Alternaria alternate (Fr.) Keissler. Supplement with salicylic acid, CaCl2 and chitosan resulted in a significant increase in biocontrol effect of B. subtilis J18. It also showed that the biocontrol effect of B. subtilis J18 on pear alternaria rot could reach up to 72.81% and 77.07% when combined with 2% CaCl2 and 1% chitosan, respectively. These results revealed a potential application B. subtilis J18 as an antagonist for controlling the fruit postharvest diseases.