土壤拮抗放线菌的分离筛选及其抑菌物质特性的研究

目的从土壤中筛选拮抗能力强且抑菌特性稳定的放线菌菌株。方法采用双层琼脂法筛选出4株拮抗放线菌菌株,然后采用杯碟法测这4株菌株发酵液提取物的抗菌谱、最小抑菌浓度、热稳定性和酸碱稳定性。结果 4株菌株发酵液提取物都能抑制金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌和白色念珠菌的生长。以金黄色葡萄球菌为指示菌测发酵液提取物的最小抑制浓度,6#和9#拮抗作用较强,发酵液提取物稀释0.125mg/ml仍有抑菌作用。6#菌株在100℃处理30min后仍有40%的抑菌活性。6#菌株发酵液提取物在碱性环境条件下比在酸性环境条件下稳定。结论 4株菌株中6#菌株发酵液提取物具有拮抗能力强、最小抑菌浓度低和在碱性条件下活性较稳定的特点。

Isolation and screening of antagonistic actinomyces from soil and antibiotic activity of their fermentation broth extract

Objective To isolate and screen antagonistic actinomyces with strong inhibitory activity from soil and study the antibiotic activity of their fermentation broth extract. Method 4 antagonistic actinomyces strains were screened by using double-layer agar method. Their antibiotic spectrum,minimum inhibitory concentration were tested through cylinder plate method. Thermal stability and pH stability were also studied. Result The fermentation broth extract of the four strains inhibited the growth of Staphylococcus aureus,Escherichia co1i,Pseudomonas aeruginosa and Candida albicans.The 6# and 9# strains had stronger inhibitory effect than the others. Their fermentation broth extracts diluted to 0.125 mg/ml were still antibacterial. The 6# strain retained 40% of its antibiotic activity against Staphylococcus aureus after its fermentation broth extract was maintained at 100 ℃ for 30 minutes. The fermentation broth extract of 6# possessed relatively better pH stability in alkaline environment than in acidic environment. Conclusion Among the 4 strains,the 6# fermentation broth extract has stronger antagonistic ability,lower minimum inhibitory concentration,relatively better pH stability in alkaline environment.