苏云金芽胞杆菌挥发性物质的测定

Determination of Bacillus thuringiensis volatile substances

目的分析、鉴定苏云金芽胞杆菌(Bacillus thuringiensis,Bt)的挥发性成分。方法采用顶空固相微萃取技术(HS-SPME)对Bt的挥发性成分进行捕集,再通过气相色谱-质谱联用(GC-MS)技术对挥发性成分进行鉴定。以本实验室分离的高效苏云金芽胞杆菌FJAT-12菌株为实验菌株,探索Bt菌株的不同培养方式、不同固相微萃取吸附方式及不同萃取头的选择对挥发性成分鉴定结果的影响,确定Bt菌株挥发性物质测定的最优方法。结果采用NA液体培养基培养,选择水浴至气-液平衡再吸附的吸附方式,采用65μm PDMS/DVB萃取头的萃取效果最佳。Bt菌株的挥发性成分主要为6-甲基-2-庚酮、2,4-二氨基甲苯、苯甲醇、2,3-二乙基-5-甲基吡嗪、2-甲基萘、2,3-Dimethy1-5-isopentylpyrazine、十四烷、正十二烷、2-甲硫基苯并噻唑。结论HS-SPME/GC-MS效果好,方法实用,便于操作,适用于对Bt挥发性成分进行分析,从而为食品安全评估提供理论依据。

Objective To analyze and identify the volatile substances of Bacillus thuringiensis. Methods The volatile constituents of Bacillus thuringiensis were captured by headspace solid phase micro-extraction technology (HS-SPME) and identified by gas chromatography-mass spectrometry (GC-MS) tech-nology. The optimal method was used to analyze the volatile constituents of Bacillus thuringiensis FJAT-12, which was a high efficient strain separated by our lab, investigated from the culture way, adsorption pattern and fibers type. Results Bacillus thuringiensis FJAT-12 was better cultured by NA liquid medium, and volatile vial was maintained in a water bath at 50 ℃ for equilibrating (180 min) and then extracted by 65 μm PDMS/DVB fibers for 60 min. The mainly volatile constituents of Bt were 6-methyl-2-Heptanone, 4-methyl-1,3-Benzenediamine, Benzyl Alcohol, 3,5-diethyl-2-methyl-Pyrazine, 2-methyl-Naphthalene, 2,3-Dimethyl-5-isopentylpyrazine, tetradecane, eicosane, 2-(methylthio)-Benzothiazole. Conclusion The method of HS-SPME/GC-MS is effective, practical, easy for operation, and suitable for the analysis of the vo-latile substances of Bacillus thuringiensis, so as to provide theoretical basis for food safety assessment.