Escherichia coli O157:H7是一种食源性致病菌，在某些逆境条件下可进入一种活的但非可培养（viable but nonculturable, VBNC）状态，该状态细菌用常规培养方法检测不到，从而对食品安全构成潜在威胁。作为新兴非热杀菌技术，高压二氧化碳（high pressure CO2，HPCD）能有效杀死食品中微生物，保留食品品质。但申请人在前期研究中首先报道了HPCD能诱导苹果汁中微生物进入VBNC状态，并发现其也能诱导E. coli O157:H7进入VBNC状态，这使该技术在食品加工中的应用面临挑战。针对该问题，本研究以E. coli O157:H7脱毒株为目标菌，开展HPCD对该菌株VBNC状态的诱导研究，以筛选出最佳的HPCD诱导条件；基于HPCD诱导该菌株形成VBNC状态的条件筛选，利用扫描电子显微镜和透射电子显微镜对VBNC细胞的形态特征进行分析，并利用荧光光度计和API ZYM试剂盒对VBNC细胞的生理特性进行分析，为优化加工工艺和保证食品安全奠定理论基础。

Escherichia coli O157:H7, a foodborne pathogen, can enter into a viable but nonculturable (VBNC) state in some adverse conditions. Although VBNC cells remain viable, they cannot grow in or develop colonies on nonselective media normally used for their culture, which make the VBNC cells undetectable by traditional culture methods. Therefore, VBNC cells in food systems would increase the risk of food safety. High pressure carbon dioxide (HPCD), one of the most promising non-thermal processing techniques, can kill microorganisms in food and retain food quality by the effects of pressurization, acidification, explosion, anaerobic environment and super/sub-critical conditions. However, we reported for the first time that HPCD could induce bacteria in apple juice to form the VBNC state, and then found that E. coli O157:H7 (non-toxogenic strain) could also enter into VBNC state by HPCD treatment. The discovery makes HPCD technique meet challenges in food processing. In order to optimize HPCD processing strategy and ensure food safety, this research aimed to investigate the best HPCD parameter for the induction of E. coli O157:H7 into VBNC state, and analyze the morphological characteristics and physiological property of VBNC cells by scanning electron microscope (SEM), transmission electron microscope (TEM), fluorophotometer and API ZYM kit. This research has significant value for theory and practice.