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Research Support, Non-U.S. Gov't
- Inactivation of Barotolerant Strains of Listeria monocytogenes and Escherichia coli O157:H7 by Ultra High Pressure and tert-Butylhydroquinone Combination
- Yoon-Kyung Chung , Ahmed E. Yousef
- J. Microbiol. 2008;46(3):289-294. Published online July 5, 2008
- DOI: https://doi.org/10.1007/s12275-008-0090-6
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- 8 Scopus
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Abstract
- Antimicrobial efficacy of ultra-high-pressure (UHP) can be enhanced by application of additional hurdles. The objective of this study was to systematically assess the enhancement in pressure lethality by TBHQ treatment, against barotolerant strains of Escherichia coli O157:H7 and Listeria monocytogenes. Two L. monocytogenes Scott A and the barotolerant OSY-328 strain, and two E. coli O157:H7 strains, EDL-933 and its barotolerant mutant, OSY-ASM, were tested. Cell suspensions containing TBHQ (50 ppm, dissolved in dimethyl sulfoxide) were pressurized at 200 to 500 MPa (23±2°C) for 1 min, plated on tryptose agar and enumerated the survivors. The TBHQ-UHP combination resulted in synergistic inactivation of both pathogens, with different degrees of lethality among strains. The pressure lethality threshold, for the combination treatment, was lower for E. coli O157:H7 (≥ 200 MPa) than for L. monocytogenes (> 300 MPa). E. coli O157:H7 strains were extremely sensitive to the TBHQ-UHP treatment, compared to Listeria strains. Interestingly, a control treatment involving DMSO-UHP combination consistently resulted in higher inactivation than that achieved by UHP alone, against all strains tested. However, sensitization of the pathogens to UHP by the additives (TBHQ in DMSO) was prominently greater for UHP than DMSO. Differences in sensitivities to the treatment between these two pathogens may be attributed to discrepancies in cellular structure or physiological functions.
- Glutathione Content and the Activities of GlutathioneSynthesizing Enzymes in Fission Yeast are Modulated by Oxidative Stress
- Yuk-Young Lee , Su-Jung Kim , Eun-Hee Park , Chang-Jin Lim
- J. Microbiol. 2003;41(3):248-251.
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Abstract
- Glutathione (GSH) is an important factor in determining tolerance against oxidative stress in living organisms. It is synthesized in two sequential reactions catalyzed by [gamma]-glutamylcysteine synthetase (GCS) and glutathione synthetase (GS) in the presence of ATP. In this work, the effects of three different oxidative stresses were examined on GSH content and GSH-related enzyme activities in the fission yeast Schizosaccharomyces pombe. GSH content in S. pombe was significantly enhanced by treatment with hydrogen peroxide, [beta]-naphthoflavone (BNF) and tert-butylhydroquinone (BHQ). Simultaneously, they greatly induced GCS and GS activity. However, they did not have any effects on glutathione reductase activity. These results suggest that GCS and GS activities in S. pombe are upregulated by oxidative stress.
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