中华真地鳖共附生放线菌DB2C2的筛选和鉴定

利用稀释平板法从中华真地鳖体内分离得到52株共附生放线菌,活性筛选表明菌株BD2C2具有较好的抗菌活性,其发酵液对金黄色葡萄球菌的抑菌圈直径超过23mm,对枯草芽胞杆菌的抑菌圈直径约17.5mm,对大肠杆菌也有一定的抑制作用。进一步研究表明其活性物质主要集中在中等极性部位。在供试浓度为每张滤纸片30μg时,菌株BD2C2发酵液的乙酸乙酯提取物对金黄色葡萄球菌、枯草芽胞杆菌和大肠杆菌的抑菌圈直径分别约27.5、22.4和10.7mm,其抑制活性与阳性对照硫酸庆大霉素相当。利用形态学观察和分子生物学方法初步鉴定该菌为Streptomyces sp.,为一个潜在新种。作为微生物源杀菌剂,DB2C2具有一定开发潜力,值得进一步研究。

Antimicrobial activity and identificaion of symbiotic or epiphytic actinomycetes strain DB2C2 from Eupolyphaga sinensis

Fifty-two symbiotic or epiphytic actinomycetes were isolated from Eupolyphaga sinensis by the dilution plate method.The screening of antimicrobial activity showed that strain BD2C2 had good antibacterial activity.The inhibition zone diamerers of the fermentation broth of BD2C2 were more than 23 mm against Staphylococcus aureus and about 17.5 mm against Bacillus subtilis.In addition,the fermentation broth of BD2C2 had a certain inhibitory effect against Escherichia coli.Further study showed that the active substances were mainly concentrated in the middle polar parts.When the test concentration was 30 μg per filter paper,the inhibition zone diameters of the ethyl acetate extract of the fermentation broth were about 27.5,22.4 and 10.7 mm against S.aureus,B.subtilis and E.coli,respectively,which were comparable to those of positive control of gentamicin sulfate.By the morphological characteristics and gene sequence analyses,DB2C2 was identified as Streptomyces sp.and was a potential new species.DB2C2 is worthy to be studied further as a potential microbial source of antimicrobial agent.