テーマ

飲食料品加工（その他）

研究機関名

The University of Georgia

代表者名

Professor Yen-Con Hung

発表概要文

Microorganisms exhibit differing responses when exposed to conditions that are unfavorable for their proliferation. The viable but nonculturable (VBNC) state can occurs when living cells lose their ability to grow on media but can return to a state of culturability (resuscitation) and exhibit virulence when the stresses are removed. This presentation investigated whether bacteria treated by the electrolyzed (EO) water has the potential of entering the VBNC state. E. coli O157:H7 was exposed to varying free chlorine concentrations of EO water and cells were recovered on Sorbitol MacConkey agar plates and Tryptic Soy enrichment broths. For VBNC determination, 3 µL of a mixture of propidium iodide and SYTOTM 9 dyes was added to 1 mL of each treated sample and subsequently analyzed in a flow cytometer. EO water treatments with low chlorine concentrations resulting in growth only observed after enrichment and up to 4% of cells remained in the live region of flow cytometric profiles. Resuscitation was triggered by the combined effect of elevated temperature and the addition of sodium pyruvate and TweenTM 20 in the medium. This study demonstrated although EO water treatments lead to great reductions in E. coli O157:H7 cells, some cells may enter the VBNC state when chlorine concentration was low with the potential to resuscitate and cause serious food safety concerns.