中文摘要：

为探明纳木错盐湖中度嗜盐放线菌的数量、种类组成、拮抗活性和酶活性。采用盐浓度为5%和10%的4种分离培养基,利用稀释平板倾注法对盐湖土壤和水样放线菌进行分离,通过形态特征、培养特征和细胞壁化学组成对放线菌进行初步鉴定,并对分离到的放线菌进行抑菌和酶活性试验。结果表明：从纳木错盐湖土壤和水样中分离到36株中等嗜盐放线菌,其中土样中26株,水样中10株。分别属于链霉菌属（Streptomyces）、诺卡氏菌属（No-cardia）、拟诺卡氏菌属（Nocardiopsis）和红球菌属（Rhodococcus）。放线菌形态学排重后合并为13株,抑菌活性实验结果表明,分别有4株放线菌对小麦赤霉菌、小麦根腐病菌和烟草赤星病菌有抑菌活性,抑菌率占30.8%。其中对小麦根腐病菌的抑制活性最强,最大抑菌圈直径达22 mm。酶活性测定发现,纳木错盐湖中度嗜盐放线菌的酶活性菌株数少且弱。

英文摘要：

The quantity,antibacterial activity and species composition of moderately-halophilic actinomycetes isolated from the Nam Co Lake,a salt lake in Tibet,were researched.The samples collected from the Nam Co Lake were isolated with 4 isolation media containing 5% and 10% NaCl by dilution plate pouring process.Based on morphological characters,culture characters and cell-wall chemical composition,the strains were preliminarily identified,and the bacteriostasis and enzymatic activity of the isolated actinomycetes were tested.The results show that 36 strains of moderately-halophilic actinomycetes were isolated,in which 26 strains were isolated from soil samples and 10 from water samples.They were identified as Streptomyces,Nocardia,Nocardiopsis and Rhodococcus.The trains were merged into 13 trains based on the morphological characters of the actinomycetes.The results of antibacterial activity experiment showed that there were 4 strains of actinomyces to have a bacteriostatic activity to Fusarium graminearum,Bipolaris sorokinianum and Alternaria alternata,and the antibacterial rate accounted for 30.8%.The restriction activity was the highest to Bipolaris sorokinianum,and the largest antibacterial circle diameter was up to 22 mm.