初始pH对嗜线虫致病杆菌YL001菌株抑菌活性及代谢的影响  

Effect of initial pH on antimicrobial activity and metabolism of Xenorhabdus neamatophila strain YL001

作　　者：郭树奇 许鹏[1] 鲁梅[1] 王泽宇 王永宏[1] 张兴[1] 

机构地区：[1]西北农林科技大学无公害农药研究服务中心,陕西杨凌712100 [2]陕西省杨凌区高新中学,陕西杨凌712100

出　　处：《西北农林科技大学学报（自然科学版）》2016年第6期132-140,共9页Journal of Northwest A&F University(Natural Science Edition)

基　　金：国家自然科学基金项目(31171910);陕西省自然科学基金重点项目(2014JZ004);中央高校基本科研创新重点项目(Z109021304)

摘　　要：【目的】研究初始培养pH对Xenorhabdus neamatophila YL001发酵液抑菌活性的影响,为进一步提高YL001的抑菌活性提供理论依据。【方法】采用生长速率法、琼脂扩散法、活体组织法,分别测定了初始pH 4.5,5.5,6.5,7.0,7.5和8.5培养条件下,X.neamatophila YL001发酵液及其乙酸乙酯提取物的抑菌活性;同时采用HPLC、LC-MS分析了乙酸乙酯提取物中代谢物的差异。【结果】随着初始pH的升高,共生菌发酵液及其乙酸乙酯提取物的抑菌活性也逐步提高。pH8.5时,YL001发酵液对水稻瘟疫病菌(Magnaporthe grisea)、辣椒疫霉病菌(Phytophthora capsici)、番茄灰霉病菌(Botrytis cinerea)、苹果轮纹病菌(Physalospora piricola)、番茄早疫病菌(Alternaria solani)、甘蓝黑斑病菌(Alternaria brassicae)以及枯草芽孢杆菌(Bacillus subtilis)均具有最强的抑制作用,发酵液乙酸乙酯提取物对番茄灰霉病的EC50为1.29mg/mL,对枯草芽孢杆菌的抑菌圈直径为14.65mm。随着初始培养pH的升高,YL001发酵液及乙酸乙酯提取物对番茄灰霉病的治疗和保护作用也逐渐提高,保护作用明显优于治疗作用。HPLC和LC-MS代谢分析表明,pH8.5、pH 7.0及pH 4.5培养条件下发酵液乙酸乙酯提取物中代谢物含量存在显著差异。【结论】初始培养pH可以显著影响X.neamatophila YL001的抑菌活性及代谢能力,碱性条件更有利于活性物质的产生及其稳定性的保持。[Objective] This study aimed to provide theoretical basis for improving bacteriostatic activi- ty of Xenorhabdus neamatophila YL001 strain through investigating the effect of initial pH on its antimi- crobial activity. [Method] Antifungal activities of fermented liquid and ethylacetate extract of X. nernato- phila YL001 under different initial pH values of 4. 5,5. 5,6. 5,7. 0,7. 5 and 8. 5 were measured using growth rate method,agar diffusion method, and biopsy method. The differences in metabolism of ethylace tate extract of X. neamatophila YL001 were also analyzed using HPLC and LC-MS. [Result] Antimicrobi- al activities of fermented liquid and its ethylacetate extract were improved with the increase of initial pH.Fermented liquid of YL001 exhibited highest inhibitory effect on mycelia growth of Magnaporthe grisea, Phytophthora capsici , Botrytis cinerea , Ph ysalospora piricola ,Alternaria solani ,Alternaria brassicae , and Bacillus subtilis at pH of 8.5. Ethylacetate extract of fermented liquid exhibited high inhibitory activity a- gainst Botrytis cinerea with ECs0 of 1.29 mg/mL and against Bacillus subtilis with antibacterial zone diam- eter of 14.65 mm. The therapeutic and protective effects o~ YL001 on B. cinerea were also improved with the increase of initial pH. The protective efficacy was higher than therapeutic efficacy. HPLC and LC-MS revealed that the production of metabolites was regulated by culture conditions. The metabolites of organic extracts from X. neamatophila YL001 had significant difference at pH values of 8.5,7.0 and 4.5. [Conclusion] The initial pH significantly affected the antimicrobial activity and metabolism of X. neamatophila YL001 ,and alkaline condition was conductive to produce active substance.

关 键 词：嗜线虫致病杆菌 初始pH 胞外产物 抑菌活性 

分 类 号：S482.292[农业科学—农药学]