Diversity and bioactivity analysis of actinomycetes isolated from Cibagou Nature Reserve soil | 慈巴沟自然保护区土壤放线菌区系分析及其生物活性测定

Chinese. 分析西藏察隅慈巴沟自然保护区土壤放线菌的组成及其抑菌活性和酶活性，为放线菌新药物先导化合物和高活性酶的筛选提供资源。从慈巴沟自然保护区采集不同植被和不同海拔高度的45份土样，用5种培养基分别分离高温、中温和低温放线菌，根据形态和化学分类特征对分离到的放线菌进行鉴定。采用植物相似性系数计算公式，将慈巴沟土壤放线菌区系与临近地区云南、青海以及地理位置及气候条件具有显著差异的河北承德和武陵山放线菌区系进行比较分析，并采用琼脂移块法，检测了617株中温放线菌对2株细菌和3株农作物病原真菌的抑菌活性及酶活性。慈巴沟自然保护区土壤放线菌区系复杂，从45份土样中共分离到11个属的放线菌。该地土壤中广泛分布着高温放线菌，其分布的上限海拔为4 000 m，主要属于链霉菌属、小单孢菌属和高温放线菌属；中温放线菌较复杂，共分离到10个属的中温放线菌；低温放线菌组成简单，仅分离到3个属。在区系亲缘关系上，慈巴沟放线菌与云南区系较为接近，与武陵山、河北承德及青海区系较远。617株中温放线菌中的大部分菌株能利用明胶、还原硝酸盐和产生凝乳酶等，对农作物病原真菌拮抗比率小，但活性较强。慈巴沟自然保护区原始森林土壤蕴涵着种类和活性丰富的放线菌，从该地区酸性土壤中能筛选到对植物病原真菌有较强活性的拮抗放线菌。

English. The composition, antibacterial activity and enzyme activity of soil actinomycetes in Cibagou Nature Reserve of Chayu, Tibet were analyzed, which could also provide microbial resources to screen new drug lead compounds and highly active enzymes. The thermophilic, mesothermal and psychrophilic actinomycetes were separated and cultivated by 5 kinds of media from 45 soil samples that were sampled from different vegetations and altitudes in Cibagou Nature Reserve. Actinomycetes were classified according to their morphological and chemical characteristics. Plant similarity calculation formula was used to analyze the similarities among soil actinomycetes flora in Cibagou Nature Reserve, neighboring areas in Yunnan and Qinghai, as well as significantly different geographical locations and climatic conditions in Chengde, Hebei, and Wuling Mountain. A variety of enzyme activities and antimicrobial activities of 617 mesothermal actinomycetes were analyzed by Agar block shift methods to 2 bacteria strains and 3 pathogenic fungus strains. The soil actinomycetes flora were complex and 11 genera were found. Thermophilic actinomycetes were widely distributed under the altitude of 4 000 m in soil. The dominant genera were Stretomyces, Micromonospora and Thermoactinomyces. 10 genera of mesothermal actinomycetes and 3 genera of psychrophilic actinomycetes were found simultaneously. The soil actinomycetes groups were related more closely to that of Yunnan than that of Wuling Mountain, Chengde in Hebei and Qinghai areas. 617 mesothermal actinomycetes could use gelatin, nitrate reduction and condensate lactasin, and had low antagonistic ratio to crop pathogenic fungus but strong activities. Cibagou Nature Reserve implies rich and strong activity of actinomycetes in primeval forest soils,strong antagonistic activity of actinomycetes to plant pathogenic fungus can be screened in acidic soils in Cibagou Nature Reserve.