螺旋毛壳ND35抗生素的产生及其在病害生物防治中的作用

Production of antibiotics by Chaetomium spirale ND35 and the role in biocontrol of plant diseases

内生菌螺旋毛壳Chaetomium spirale ND35是一株广谱拮抗性生防因子。为了阐明菌株ND35抗生素在植物病害生物防治中的作用机制,系统研究了抗生素的产生、提取纯化及其在离体和温室条件下的抑菌防病作用。菌株ND35的发酵液经乙酸乙酯萃取,浓缩得黄褐色抗生素粗提液。平皿抑菌试验表明,抗生素粗提液对20余种植物病原真菌有抑制作用,浓度为400μg/mL时对病菌菌丝生长的抑制率范围从14．4%到72．6%。浓度为500μg/mL和1000μg/mL的抗生素粗提液对新月弯孢分生孢子萌发的抑制率分别是54．2%和75．9%。发酵时间也影响抗生素的产量,马铃著葡萄糖液体培养基中发酵15天时,抗生素产量最高。经薄层层析和高效液相色谱检测,证明有两个活性组分。温室试验表明,该抗生素粗提液稀释50倍液对玉米弯孢叶斑病的防治效果可达85．5%,稀释250倍液防治效果达63。3%。试验结果表明,抗生素是菌株ND35重要的生防决定因子之一,抗生素粗提液也展示了对玉米弯孢叶斑病具有较好的生防潜能。

The endophytic Chaetomium spirale ND35 is a potential biocontrol agent with a wide range of antifungal activities. In this study, production, extraction and purification of the antibiotics by C. spirale ND35, as well as the antifungal activity in vitro and in vivo were systemically investigated in order to explore the mechanism of antibiotics produced by ND35 involved in biocontrol activity. The culture filtrate of the strain ND35 was extracted by ethyl acetate, concentrated, and the brown crude extracts were obtained. Bioassay of antifungal activity showed that the crude extracts significantly suppressed mycelial growth of several phytopathogenic fungi in vitro. The suppression percentage of mycelial growth of the phytopathogens ranged from 14.4% to 72.6% at a concentration of 400μg/mL of the crude extracts, and the inhibition percentage of conidia germination of Curvularia lunata was 54.2% and 75.9% at concentrations of 500 μg/mL and 1000μg/mL, respectively. Yield of the crude extracts produced by C. spirale ND35 in PDB reached to the maximum after incubation for 15 d. Two active fractions were purified by TIE and HPLC analyses. In greenhouse experiments, the control efficacy of Curvularia leaf spot of maize reached 85.5% and 63.3% with antibiotics extract in 50 fold dilution and 250 fold dilution. The antibiotics produced by strain ND35 as an important determinant involved in antffungal activity as well as the potential to control Curvularia leaf spot of maize.