1株抗耐甲氧西林金黄色葡萄球菌放线菌的鉴定及其代谢产物活性分析

Identification of an Actinomycetes strain with resistance to MRSA and activity of its metabolites

【目的】对从原始森林土壤中分离得到的1株抗耐甲氧西林金黄色葡萄球菌的放线菌AF1进行分类鉴定,并对其代谢产物活性进行分析。【方法】通过菌株形态学特征、生理生化特征观察和16SrDNA序列分析,对AF1菌株进行分类鉴定;采用琼脂平板打孔法,测定AF1菌株发酵产物的稳定性及AF1菌株发酵产物乙酸乙酯粗提物对耐甲氧西林金黄色葡萄球菌的抑菌活性。【结果】电子显微镜观察显示,AF1菌株分生孢子直或呈波浪弯曲状,孢子链呈松散螺旋状,AF1菌株能利用葡萄糖、D-半乳糖、麦芽糖、鼠李糖和蔗糖,不能利用D-果糖、D-甘露醇和肌醇,可以水解淀粉但不能水解纤维素。AF1菌株16SrDNA序列全长1 242bp（GenBank ID：KF059834.1）,与加利利链霉菌XSD-102（Streptomyces galilee XSD-102）的相似度为100%,初步确定菌株AF1为加利利链霉菌（S.galilee）;AF1发酵产物对外界环境不敏感,在30～80℃下活性稳定,90℃处理60min时活性丧失,在pH 2～10下活性稳定,耐受紫外线照射;其乙酸乙酯提取物对耐甲氧西林金黄色葡萄球菌的最低抑菌质量浓度（MIC）为68μg/mL。【结论】AF1菌株为加利利链霉菌（S.galilee）,其代谢产物对耐甲氧西林金黄色葡萄球菌具有抗菌活性。

【Objective】The purpose of this work was to identify and characterize the Streptomyces strain AF1,which was selected from Madagascar forest soil with resistance to MRSA.【Method】The strain AF1 was characterized by observation of morphology,physiological and biochemical characterizations and16 SrDNA sequence analysis.Using agar diffusion plate method,the stability of fermentation products of AF1 and the resistance to MRSA were measured.【Result】The conidium of AF1 strain was straight or wavy curved,and the spore chain was loose spiral.AF1 strain could use glucose,galactose,sucrose,maltose and rhamnose but not fructose,mannitol and inositol.AF1 strain could hydrolyze starch but not cellulose.The 16 SrDNA of AF1 was 1 242bp（GenBank ID：KF059834.1）,having the homology of 100% with potato scab pathogen XSD-102.The antimicrobial substance was not sensitive to the external environment.It had stability when pH was 2-10,temperature was 30-80℃,or under ultraviolet radiation.The activitywas lost when treated by 90℃for 60 min.The MIC of ethyl acetate extract against MRSA was 68μg/mL【Conclusion】AF1strain was identified as Streptomyces galilee AF1 and its metabolites showed antimicrobial activity against MRSA.