| Autor: |
S, Koseki, M L, Tamplin, J P, Bowman, T, Ross, T A, McMeekin |
| Rok vydání: |
2011 |
| Předmět: |
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| Zdroj: |
Letters in applied microbiology. 54(3) |
| ISSN: |
1472-765X |
| Popis: |
To elucidate the potential use of microelectrode ion flux measurements to evaluate bacterial responses to heat treatment.Escherichia coli K12 was used as a test bacterium to determine whether various heat treatments (55-70°C for 15 min) affected net ion flux across E. coli cell membranes using the MIFE™ system to measure net K(+) fluxes. No difference in K(+) fluxes was observed before and after heat treatments regardless of the magnitude of the treatment. Applying hyperosmotic stress (3% NaCl w/v) during flux measurement led to a net K(+) loss from the heat-treated E.coli cells below 65°C as well as from nonheated cells. In contrast, with E. coli cells treated at and above 65°C, hyperosmotic stress disrupted the pattern of K(+) flux observed at lower temperatures and resulted in large flux noise with random scatter. This phenomenon was particularly apparent above 70°C. Although E. coli cells lost the potential to recover and grow at and above 62°C, K(+) flux disruption was not clearly observed until 68°C was reached.No changes in net K(+) flux from heat-stressed E. coli cells were observed directly as a result of thermal treatments. However, regardless of the magnitude of heat treatment above 55°C, loss of viability indicated by enrichment culture correlated with disrupted K(+) fluxes when previously heated cells were further challenged by imposing hyperosmotic stress during flux measurement. This two-stage process enabled evaluation of the lethality of heat-treated bacterial cells within 2 h and may be an alternative and more rapid method to confirm the lethality of heat treatment.The ability to confirm the lethality of thermal treatments and to specify minimal time/temperature combinations by a nonculture-dependent test offers an alternative system to culture-based methods. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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