珠芽蓼内生细菌ZA1的抑菌物质产生条件的优化及其稳定性测定

从珠芽蓼中分离的内生细菌ZA1对马铃薯坏疽病菌具有良好的抑菌效果,鉴定为莫海威芽孢杆菌。本文通过平板对峙法对ZA1分泌物抑制马铃薯坏疽病菌的培养条件进行了优化,并对ZA1抑菌粗提物的稳定性进行了测定。结果表明,ZA1的最佳培养基为B培养液,最佳发酵温度为17.8℃,培养基的最佳pH是6.9,150mL三角瓶的最佳装液量为20mL,最佳培养方式为暗处理振动培养96h,经对ZA1进行优化培养,其对马铃薯坏疽病菌的EC50=0.1228μL/mL,是优化前EC50=4.5888μL/mL的37倍。ZA1的抑菌粗提物90℃下处理2h,其相对活性达到76.62%,具有耐高温的特性;对紫外线照射30min后相对活性差异不明显;pH为3和11时,其相对活性分别为92.87%和85.11%;对蛋白酶和Ag+、Cu2+、Zn2+和Fe3+等金属离子不敏感,经Ag+处理后的相对活性可达到86.93%。

Optimizing the culture conditions and determining the stability of antibiotic secretion by Polygonum viviparum of the endophytic bacteria Bacillus mojavensis

One strain of Bacillus mojavensis (ZA1 )is known to have a strong antibacterial effect against the pathogen of potato gangrene (Phomafoveata ).In this study,P .foveata was isolated as a fungal pathogen and the method of petri dish confrontation was used to determine culture conditions for optimizing and stabilizing production of the antibiotic secreted by ZA1.The results showed that the optimum culture medium for ZA1 consisted of 200 g potato,10 g peptone,20 g sucrose and 1000 mL distilled water.The optimum fermentation temperature of ZA1 was 17.8℃.The optimum pH value of ZA1’s culture medium was 6.9.The optimum 150 mL triangle bottle volume of ZA1 was 20 mL.The optimum culture mode of ZA1 was shaking cultivation in the dark for 96 hours.Results showed that the EC50 =0.1228 μL/mL against P .foveata after optimization was 37 times higher than the EC50 =4.5888 μL/mL against P .foveata before optimization.Crude extracting of bac-teriostatic from ZA1 showed that the characteristics of high temperature resistance and relative activity could reach 76.62% after it was treated at 90℃ for 2 hours.Relative activity was stable and could not be destroyed under UV irradiation for 30 minutes.The bacteriostatic extract of ZA1 had good acid and alkali resistance. When it was treated by pH=3 and pH=11,the relative activity was 92.87% and 85.11% respectively.It was not sensitive to protease and heavy metal ions such as Ag+ ,Cu2 + ,Zn2 + and Fe3 + .Relative activity remained at 86.93% after Ag+ treatment.