链霉菌Sa-21对烟草黑胫病的防效及抑菌作用研究

烟草疫霉引起的烟草黑胫病，是烟草生产上的重要病害之一。为了明确链霉菌Sa-21防治烟草黑胫病的应用潜力，用盆栽试验测定了链霉菌Sa-21的生防效果，并用生长速率法等手段探讨了链霉菌Sa-21对烟草疫霉的抑菌作用。盆栽试验表明，链霉菌Sa-21菌株发酵液对苗期和成株期烟草黑胫病有较好的控制效果，最高防效可达98.39%。菌株Sa-21粗浸膏对烟草疫霉菌丝生长的抑菌中浓度为56.1μg/mL,50μg/mL的粗浸膏处理后可以降低50%的菌丝生物量。菌株Sa-21粗浸膏对烟草疫霉孢子囊的产生、游动孢子释放、休止孢萌发以及细胞膜透性均有抑制作用，100μg/mL的粗浸膏基本能够完全抑制孢子囊的产生，并且对游动孢子释放的抑制率达50%以上；粗浸膏浓度为150μg/mL时，对休止孢萌发的抑制率达94.35%；随着粗浸膏浓度增加，菌丝细胞膜的透性也会加大。研究结果表明，链霉菌Sa-21代谢物对烟草疫霉的生长繁殖产生抑制作用，并为链霉菌Sa-21生防菌剂的开发及其对烟草黑胫病的防治提供了理论依据。

Study on the Antibacterial Action and Control Effect of Streptomyces Sa-21 against Phytophthora nicotianae

Tobacco black shank caused by Phytophthora nicotianae is one of the important diseases. This study was aimed to clarify the application potential of Streptomyces Sa-21 to the disease control and provide a reference for basic research on the biological control of tobacco black shank. The biocontrol effect of Streptomyces Sa-21 was determined by pot experiment, and the antibacterial effect of Streptomyces Sa-21 on P. nicotianae was investigated by growth rate method. In pot experiment, the control effect of fermentation solution of Streptomyces Sa-21 reached a maximum inhibition rate with 98.39% on P. nicotianae at the seedling and adult stage of tobacco. The crude extractof Streptomyces Sa-21 of reduced 50% mycelial biomass at the concentration of 50 μg/mL, and EC₅₀ of 56.1 μg/mL. The crude extract at 100 μg/mL completely inhibited the production of sporangia and 50% of sporangia release. The concentration of 150 μg/mL inhibited the germination of cystcspore by 94.35%. The results showed that Streptomyces Sa-21 metabolites could inhibit the growth and reproduction of P. nicotianae, and provided a theoretical basis for the development of Streptomyces Sa-21 biocontrol agents and the control of tobacco black shank.