Isolation and Identification of Viola philippica Rhizosphere Bacteria and Analysis of their Fermentation Products

摘要

Dilution plating procedure was adopted to isolate strains from the rhizosphere soil of medicinal plants Viola philippica (Viola yedoensis Makino). The pathogenic bacteria isolated in clinic were used as the indicator bacteria and the active strains were screened by fixed agar block method. Biological characteristics of the strains with a strong antibacterial activity were analyzed. The strains were identified and classified, and the antibacterial activity was determined by disk diffusion test. The antibacterial activity components were analyzed in combination with the extraction. Two strains Z1-7 and Z1-13a were screened from 21 strains, which showed a stronger antibacterial activity against the indicator bacteria. Z1-7 was an unknown species of Streptomyces and Z1-13a was California Streptomyces. The fermentation broth of the both strains had a strong antibacterial activity against Staphylococcus aureus, Escherichia coli and Staphylococcus epidermidis. The diameter of their inhibition zones was 10.0~15.5 mm. Z1-13a had a strong antibacterial activity against Pseudomonas aeruginosa and Citrobacter freundii. The antibacterial substances in Z1-7 and Z1-13a fermentation broth were lipid- and water-soluble substances, respectively. Both the above strains have a good antibacterial activity against common drug-resistant bacteria in clinic. Results suggest the potential value of strains Z1-7 and Z1-13a in research and development of new antibiotics against drug-resistant pathogens.