Sterilization of Bacillus tequilensis isolated from aerogenic vinegar by intense pulsed light

摘要

Herein Bacillus tequilensis was chosen as a representative strain isolated from aerogenic vinegar produced by solid-state fermentation (SSF) for the purpose of this research to elucidate the bacterial inactivation mechanisms of intense pulsed light (IPL) at cellular and molecular levels. The optimum sterilization conditions of IPL for this strain were obtained by using response surface methodology (RSM), resulting in an average lethality of 99.98%. The results showed that IPL at the optimum sterilization conditions caused a destructed structure of the B. tequilensis strain. Its intracellular nucleic acid and proteins seeped out of the IPL-treated strain showing a positive relationship between the concentration of nucleic acid and proteins in the culture medium and the bacterial lethality. Extracellular calcium ions flowed in the IPL-treated strain, resulting in a higher concentration of calcium ions. Comparative proteomic analysis showed that there were 46 up-regulated proteins and 58 down-regulated proteins in the IPL-treated strain culture compared with the IPL-untreated strain culture. Western blot analysis confirmed the up-regulation of four proteins catalase 1, catalase 2, chitosanase and gamma-glutamyltransferase. It indicated that there existed stress reacting processes in the IPL-treated strain during its sterilization process.