从辣椒果实中分离、筛选出了一株对辣椒炭疽病菌具有拮抗作用的内生细菌P5，通过菌体、菌落形态观察、生理生化测定及16S rDNA序列分析，鉴定P5为枯草芽孢杆菌。以辣椒炭疽病作为指示菌，测定其发酵滤液理化性质。用发酵滤液处理辣椒进行采后保鲜研究，测定品质指标：质量损失率、腐烂率、可滴定酸含量、Vc含量、总糖含量、叶绿素含量等品质指标。结果表明，发酵滤液热稳定性良好，在pH 8.0以下，40~100 ℃范围内，抑菌活性稳定无变化，121 ℃处理30 min活性有所下降，为对照组的85%；对pH稳定，在室温下，pH 2.0~12范围内，抑菌活性不发生变化；对紫外线稳定，经紫外光照射12 h，其活性仍为对照的89.87%。发酵滤液处理过的辣椒保鲜效果明显优于无菌水对照组，显著降低了辣椒失重率和腐烂率，并有效抑制了果实中可滴定酸、Vc、总糖、叶绿素等含量的减少，对辣椒有显著的保鲜效果。

An antagonistic endophytic bacterium strain (P5) against Colletotrichum capsici was isolated from capsicum fruits, and identified as Bacillus subtilis based on observations of bacterial cell and colony morphologies, physiological and biochemical measurements, and 16S rDNA sequence analysis. The physical and chemical properties of the crude fermentation extract were determined with Colletotrichum capsici as the indicative bacterium. In addition, the fresh-keeping effects of the crude fermentation extract of P5 on postharvest capsicum were studied by measuring the weight loss rate, rate of decay, titratable acidity, and the contents of vitamin C, total carbohydrates, and chlorophyll, along with other quality indices of capsicum. The results indicated that the crude fermentation extract had good thermal stability, and the antibacterial activity was stable, showing no changes in an environment with a pH value <8.0 and a temperature range from 40~100 ℃. The antibacterial activity decreased to 85% of that of the control group after treatment at 121 ℃ for 30 min. No changes in the antibacterial activity were observed from pH 2.0 to pH 12.0 under room temperature, showing good stability to pH fluctuations. The crude fermentation extract was stable to ultraviolet (UV) light and could maintain 89.87% of the initial activities under UV irradiation for 12 h. The crude fermentation extract treatment group exhibited better fresh-keeping effect on postharvest capsicum compared with the sterile water treatment group, and the fermentation extract could effectively reduce the weight loss rate and rate of decay. The treatment inhibited the reductions in titratable acidity and the contents of vitamin C, total carbohydrates, and chlorophyll, showing an apparent fresh-keeping effect on capsicum.

国家科技支撑计划项目（2015BAD16B00, 2015BAD16B01）；国家自然基金项目（31071738, 31000827）；湖南省教育厅重点项目（10A051）；湖南省自然基金项目（09JJ-3032）；湖南农业大学稳定人才项目（07WD18）；长沙市科技局项目（K1308044-21）；湖南省研究生科研创新项目（CX2013B310）