RESUMEN
Objective To isolate and identificate Streptomyce strain from cow dung and observe its antimicrobial activity. Methods Strains were isolated from cow dung by dilution coating method.Strong antibacterial strains were screened out by agar block method with fixed Staphylococcus aureus and Escherichia coli as indicative bacteria.The strains were identified based on physiological and biochemical characteristics as well as 16S rDNA gene sequence analysis.Active antibacterial fermentation broth substance was determined by disk diffusion method,and antibacterial active substance of strains fermentation broth was extracted by water-saturated n-butanol.Antibacterial substance of strains was identified by Molish reaction,biuret test and ninhydrin reaction. Results Eight strains were isolated from cow dung and one strong antibacterial strain was screened out and named B5-2,identified as Streptomyces.The results showed that the strain had the highly antibacterial effect on Staphylococcus aureus,Escherichia coli,Citrobacter freundii,Enterobacter cloacae,Klebsiella pneumoniae,Enterobacter aerogenes.The strain antibacterial active substance of fermentation broth preliminary analysis showed that strong antibacterial active substance of B5-2 was the water-soluble substance.Antibacterial substance of B5-2 was preliminarily identified as glycoside and protein by Molish reaction,biuret test and ninhydrin reaction. Conclusion The strain isolated have a strong inhibition effect on clinical pathogenic bacteria in clinical practice.