AUTHOR=Li Jiao , Ma Luyao , Liao Xinyu , Liu Donghong , Lu Xiaonan , Chen Shiguo , Ye Xingqian , Ding Tian 

TITLE=Ultrasound-Induced Escherichia coli O157:H7 Cell Death Exhibits Physical Disruption and Biochemical Apoptosis

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02486

DOI=10.3389/fmicb.2018.02486

ISSN=1664-302X

ABSTRACT=<p>Ultrasound has attracted great interest of both industry and scientific communities for its potential use as a physical processing and preservation tool. In this study, <italic>Escherichia coli</italic> O157:H7 was selected as the model microbe to investigate the ultrasound-induced cell death. Slight variations in membrane potential and ion exchanges across membrane induced by low-intensity ultrasound increased the membrane permeability of <italic>E. coli</italic> O157:H7, and this reversible sublethal effect can preserve the viability of <italic>E. coli</italic> O157:H7 and meanwhile be beneficial for bioprocessing application. In comparison, high-intensity ultrasound resulted in irreversible lethal effect on <italic>E. coli</italic> O157:H7, which can be applied in the field of microbial inactivation. In addition, both low- and high-intensity ultrasound induced either physical destruction or trigger genetically encoded apoptosis of <italic>E. coli</italic> O157:H7. Accumulation of reactive oxygen species and decrease of adenosine tri-phosphate might be related to the physiological and biochemical hallmarks of apoptosis, including exposed phosphatidylserine and activated caspases in <italic>E. coli</italic> O157:H7. The result provides novel insight into the mechanisms of non-thermal physical treatment on the inactivation of bacteria and lays foundation for the further research on the cell signaling and metabolic pathway in apoptotic bacteria.</p>