青海高原东部土壤中拮抗性放线菌的生态分布特征

Characteristics of ecological distribution of antimicrobial actinomycetes from soil in the eastern part of qinghai plateau

采用常规方法研究了从青海高原东部海晏、湟源、湟中、大通、西宁、互助、乐都和平安等八个县(市 ) ,粮田 (旱地和水地 )、菜地 (露地和保护地 )及自然土壤 34个样区 4 0个代表性土壤样品中分离所得 6 85株放线菌对 6种靶标菌的拮抗性。结果表明 ,(1)拮抗性放线菌占放线菌总数的比例与土壤利用方式有关 :粮田、菜地和自然土壤中拮抗性放线菌所占比例分别为 2 6 .8%、2 3.8%和 2 0 .5 % ,保护地土壤中拮抗性放线菌的比例是露地的 2倍 ,旱地土壤中拮抗性放线菌的比例明显高于水地 ;(2 )供试菌株中对大肠埃希氏菌、金黄色葡萄球菌、假丝酵母、青霉、西瓜枯萎病菌和黄瓜枯萎病菌有拮抗活性菌株数分别为 2 .8%、14 .9%、3.5 %、0 .9%、1.8%和 0 .6 %。说明供试菌株对细菌的拮抗作用强于真菌 ,对革兰氏阳性细菌的拮抗作用强于革兰氏阴性细菌 ,对单细胞真菌的拮抗作用强于丝状真菌。

The antimicrobal activity of 685 actinomycetes against six target microbes was studied by normal methods,which were isolated from 40 representative soil samples that were collected from 34 regions involved grain field (including dry field and water field) and vegetable field (including opencast field and protectorate field) and natural soil in the eastern part of Qinghai Plateau. Results indicated that: ①The percentage of antimicrobal actinomycetes to total actinomycetes had relations to their soil utilizing way, which were 26.8%, 23.3% and 20.5% in grain field, vegetable field and natural soil respectively. The percentage of antimicrobal actinomycetes in protectorate field soil was two times of opencast field one, and the dry field soil was significantly higher than the water field. Only 20.5% of the strains tested from natural soil had antimicrobal activity against strains experimented. ②2.8%, 14.9%, 3.5%, 0.9%, 1.8% and 0.6% of tested strains had antimicrobal activity against Escherichia coli, Staphylococcus aureus, Candida tropicalis, Penicillium sp., Fusarium oxysporum f .sp. Niveum and Fusarium oxysporum f .sp.Cucumerinum respectively , which illustrated that the strains tested had stronger antimicrobal activity against bacteria than fungi, had stronger antimicrobal activity against Gram positive bacteria than Gram-negative bacteria, and had stronger antimicrobal activity against single cell fungi than filament fungi.