Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan.
N Biotechnol. 2010 Sep 30;27(4):397-402. doi: 10.1016/j.nbt.2010.05.014. Epub 2010 May 24.
Microorganisms capable of utilizing vegetable tissues for growth in soils were isolated and their vegetable broth cultures were individually sprayed directly on leaves to test their ability to control Phytophthora blight of bell pepper caused by Phytophthora capsici. Liquid culture of Streptomyces strain TKA-5, a previously undescribed species obtained in this study, displayed several desirable disease control characteristics in nature, including high potency, long lasting and ability to control also black leaf spot of spoon cabbage caused by Alternaria brassicicolca. The extract was fungicidal to P. capsici but fungistatic to A. brassicicola. It was stable at high temperature and high pH. However, after exposure to pH 2 for 24h, the extract was no longer inhibitory to P. capsici although it was still strongly inhibitory to A. brassicicola. After treatment with cation or anion exchange resins, the extract lost its inhibitory effect against P. capsici but not A. brassicicola. The results suggest that the extract contained two different kinds of inhibitory metabolites, one against P. capsici with both positive and negative charges on its molecule and another against A. brassicicola with no charges on its molecule. The inhibitory metabolites were soluble in ethanol or methanol but not in water, ether or chloroform. They were dialyzable in the membrane tubing with molecular weight cut-off of 10,000, 1000 or 500 but not 100, indicating that the inhibitors have a molecular weight between 500 and 100. Results also showed that both inhibitors are not proteins.
从土壤中分离出能够利用植物组织进行生长的微生物，并将其蔬菜肉汤培养物直接喷洒在叶片上，以测试其控制辣椒疫霉引起的甜椒疫病的能力。本研究中获得的一种以前未描述的链霉菌菌株 TKA-5 的液体培养物在自然条件下显示出几种理想的病害控制特性，包括高活性、长效性和控制黑腐病的能力由交替镰刀菌引起的白菜。提取物对 P. capsici 具有杀菌作用，但对 A. brassicicola 具有抑菌作用。它在高温和高 pH 值下稳定。然而，暴露于 pH 2 24h 后，提取物对 P. capsici 不再具有抑制作用，尽管它对 A. brassicicola 仍具有强烈的抑制作用。用阳离子或阴离子交换树脂处理后，提取物失去了对 P. capsici 的抑制作用，但对 A. brassicicola 没有抑制作用。结果表明，提取物中含有两种不同的抑制代谢物，一种对 P. capsici 的分子带有正电荷和负电荷，另一种对 A. brassicicola 的分子不带电荷。抑制代谢物可溶于乙醇或甲醇，但不溶于水、乙醚或氯仿。它们可在分子量为 10,000、1000 或 500 的膜管中透析，但不能在分子量为 100 的膜管中透析，表明抑制剂的分子量在 500 到 100 之间。结果还表明，两种抑制剂都不是蛋白质。
