| Antimicrobial Peptides are a kind of bioactive little peptides which exist in biosphere widely.They are amphoteric molecules,produced by induction in organism always with positive charge.According to the difference of the resources,Antimicrobial Peptides can be divided into three kinds:animal origin,plant origin and micaobial origin.Antimicrobial lipopeptides belong to the latter,produced by Bacillus sp.with the function of antibacterial, antifungal,antivirus and antimycoplasmal without nomal cells' damage.So they are safe for human and have an important application value in pharmaceutical and biomedicine.In addition,lipopeptides can be used as a biosurfactant that widely applied in the fields of petroleum industry,food,cosmetic and agriculture.The paper stresses to study the quantitative detection method of antibacterial lipopeptide by HPLC which provides a basis for its application.This paper contained four parts as follows:1.The standard curve of penicillin efficacy was established by cylinder-plate method, which was Y=0.0057x+2.6048 with the correlation coefficients 0.9955.3 standard curves was made by repeatation and the relative standard deviation of them was within 4%.Based on the standard curve,the titer of 1g crude antimicrobial lipopeptides reached 0.93×106 IU.2.A new method of detecting the content of surfactin in fermentation broth by HPLC was established.Surfactin was detected within 20 minutes at UV 210nm on a chromatographic column of COSMOSIL 5C18-AR-Ⅱ(4.6×250mm),with a mobile phase of acetonitrile(0.1%TFA) and water(0.1%TFA) at a flow rate of 0.84mL/min by gradient elution.The results showed that by using this method,the correlation coefficient of integral area and concentration was 0.9998 within the range of 1 to 100mg/L,with precision 1.5%, detection limit 1mg/L and recovery 96.59%,respectively.3.The self-made Fengycin was relative purified,and a new method of detecting the content of fengycin in fermentation broth was established by HPLC.Fengycin was detected within 30 minutes at UV 230nm on a chromatographic column of COSMOSIL 5C18- Ms-Ⅱ(4.6×250mm),with a mobile phase of acetonitrile(0.1%TFA) and water(0.1% TFA) at a flow rate of 0.SmL/min by gradient elution.The results showed that by using this method,the correlation coefficient of integral area and concentration was 0.9921 within the range of 5 to 300mg/L,with precision 2.74%,detection limit 2mg/L.4.The titer and application of Antirnicrobial lipopeptides was studied.The titer of 1g crude Antirnicrobial lipopeptides was 1.1×106 IU by calculation using double agar plate method.The yoghurt's preservation under room temperature was researched by adding crude Antirnicrobial lipopeptides,potassium sorbate and EDTA together.The results showed that under 25℃,with the proportioning of crude Antimicrobial lipopeptides 0.5g/kg, potassium sorbate 0.2g/kg and EDTA 0.13g/kg added into yoghurt,the propagation of microorganism was obviously inhibited and the shelf life of yoghurt under room temperature could reach longer than10 days... |
PDF Full Text Request