为了寻找番茄早疫病的微生物生防制剂,减少该病害对番茄产量与品质的影响.利用共培养法和菌丝生长抑制法从土壤中筛选番茄早疫病害的拮抗菌,并考察其抗菌谱、发酵液稳定性与防效效果.结果表明:成功筛选得到 1 株拮抗番茄早疫病较强的菌株Sa-6,菌丝生长抑制法显示该菌株发酵液对番茄早疫菌丝抑制率达 60.27%;根据形态学、生理生化特征和16S rDNA序列分析结果,鉴定菌株Sa-6为微黄白链霉菌(Streptomy-ces albiflaviniger);其发酵滤液对杨树枯萎病菌、西瓜炭疽病菌等5 种病原真菌及大豆细菌性斑点、水稻细菌性条斑等 8 种病原细菌均具有较好的抑制作用;同时菌株Sa-6发酵滤液对番茄早疫病的防效可达 90%以上.因此,菌株微黄白链霉菌Sa-6有望为微生物生防制剂开发提供优良的菌种资源.

The present manuscript highlights the potential role of Streptomyces roseoverticillatus 63 (Sr-63) against Xanthomonas oryzae pv. oryzae (Xoo), which is the cause of a disastrous bacterial leaf blight disease with rice worldwide. The disease suppression was achieved under greenhouse conditions. A foliar spray of the fermentation broth of Sr-63 significantly reduced the leaf blight symptoms with rice in Xoo inoculated rice plants. Furthermore, we observed that the carbazomycin B, isolated from the fermentation broth of Sr-63, was demonstrated to have antibacterial activity against Xoo with a minimum inhibitory concentration (MIC) of 8 μg mL–1. The results indicated that carbzomycin B hampered the membrane formation of Xoo, reduced the production of xanthomonadin and extracellular polymeric substance (EPS). The fourier transform infrared spectroscopic (FT-IR) indicated that carbazomycin B changed the components of the cell membrane, then caused a change of the cell surface hydrophobicity of Xoo. Scanning electron microscopy revealed that the Xoo cells treated with carbazomycin B exhibited apparent structural deformation. The results also indicated that carbazomycin B had a negative impact on the metabolism of Xoo, carbazomycin B reduced the activity of malate dehydrogenase (MDH) activity and suppressed the protein expression of Xoo. Overall, our data suggests that Streptomyces roseoverticillatus 63 is a promising biocontrol agent that could be used to combat the bacterial leaf blight diseases of rice.

为提高菌核曲霉(Aspergillus sclerotiorum)As-68菌株发酵液对水稻白叶枯病菌的抑菌活性,用响应面法优化培养基配方和发酵条件.通过单因素实验,筛选出适宜的碳源、氮源及其浓度和适宜发酵条件,利用Plackett-Burman设计,探究碳源浓度、氮源浓度、菌龄和转速对抑制水稻白叶枯病菌影响效果,采用最陡爬坡设计和响应面分析法进一步优化,获取最适发酵培养基配方和条件.结果表明:碳源浓度、氮源浓度、菌龄和转速对抑制水稻白叶枯病菌影响效果显著;最适发酵培养基配方和条件为碳源9.46％葡萄糖、氮源0.57％黄豆粉、菌龄6 d、接种量5％、转速170 r·min-1、发酵温度28℃.经模型验证实验优化后抑菌圈直径实际值为(50.10±0.20)mm,较优化前抑菌圈直径增大了52.70％.该实验可为生物农药开发及作物病害防治提供参考,为农业科学的发展奠定基础.

为寻找水稻白叶枯病天然生防药剂,本研究利用共培养和牛津杯法分离筛选植物根际土壤放线菌,共分离纯化获得65株放线菌菌株.在8株能够拮抗水稻白叶枯病菌Xanthomonas oryzae pv.oryzae(Xoo)放线菌菌株中,Sr-63菌株对水稻白叶枯病菌拮抗能力最强,其发酵液抑菌圈直径为46.4 mm±2.3 mm.优化发酵条件后,Sr-63菌株发酵液抑菌圈直径可达50.0 mm±1.2 mm;依据形态特征、生理生化特征和系统发育分析,鉴定菌株Sr-63为玫瑰轮丝链霉菌(Streptomyces ro-seoverticillatus).抗菌谱实验结果表明,Sr-63菌株发酵液对水稻细菌性条斑病菌、大豆细菌性斑疹病菌、番茄细菌性叶斑病菌以及大豆细菌性斑点病菌4种植物病原细菌也有较好的拮抗作用.水稻白叶枯病防效实验结果表明,Sr-63菌株发酵液对水稻白叶枯病具有良好的防治效果,对'Chai Nat 2'、'KDML105'、'Khao luang'3个水稻品种的病斑抑制率均达到了90％以上,且Sr-63菌株的发酵液防治效果优于化学农药叶枯唑.