The study on extraction and antimicrobial activity of antimicrobial peptides from skin of rana chensinensis

Antimicrobial peptides were isolated from skin of Rana chensinensis by methanol.Some factor of influence on antimicrobial percentage of antimicrobial peptides crude product was reviewed,such as time,temperature,ratio of sample and extraction solvent and pH.The optimum condition was chosen by orthogonal experiment.The optimum conditions are as follows: The ratio of sample and extraction solvent is 1 ∶25.The extracting solution was disposed for 24 h at-20 ℃.And the pH of extracting solution is 5.0.Under the optimize conditions antimicrobial percentage of antimicrobial peptides can reach 75.22%.Antimicrobial peptides crude product could effectively inhibit the growth of series microorganisms,including Gram-positive bacteria,Gram-negative bacteria and fungus.The MICs of the tested microorganisms were tested as follows: The MIC of Staphylococcus aureus and Streptococcus is 0.25 mg/mL,the MIC of Bacillus subtilis and Escherichia coli is 0.5 mg/mL,the MIC of Bacillus cereus is 1.0 mg/mL,the MIC of Candida albicans,Saccharomyces cerevisia and Mucor is 2.0 mg/mL,the MIC of Rhizopu is 4.0 mg/mL.