Contribution of exofacial thiol groups in the reducing activity of Lactococcus lactis

Lactococcus lactis can decrease the redox potential at pH 7 (Eh₇) from 200 to -200 mV in oxygen free Man-Rogosa-Sharpe media. Neither the consumption of oxidizing compounds or the release of reducing compounds during lactic acid fermentation were involved in the decrease in Eh₇ by the bacteria. Thio...

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Bibliographic Details
Published in:The FEBS journal 2010-05, Vol.277 (10), p.2282-2290
Main Authors: Michelon, D, Abraham, S, Ebel, B, De Coninck, J, Husson, F, Feron, G, Gervais, P, Cachon, R
Format: Article
Language:English
Subjects:
Acids
Bacteria
Biochemistry
Carbonyl Cyanide m-Chlorophenyl Hydrazone - pharmacokinetics
Culture Media, Conditioned - chemistry
Culture Media, Conditioned - metabolism
Dicyclohexylcarbodiimide - pharmacology
Electrochemistry
Electrodes
Ethylmaleimide - pharmacology
Fermentation - drug effects
Food engineering
Hydrogen-Ion Concentration - drug effects
Lactococcus lactis
Lactococcus lactis - drug effects
Lactococcus lactis - metabolism
Life Sciences
Membrane Proteins - metabolism
Nigericin - pharmacology
Oxidation
Oxidation-Reduction - drug effects
proton motive force
Proton-Motive Force - drug effects
redox
reducing activity
Stilbenes - pharmacology
Sulfhydryl Compounds - antagonists & inhibitors
Sulfhydryl Compounds - metabolism
Sulfhydryl Reagents - pharmacology
Sulfonic Acids - pharmacology
thiol groups
Valinomycin - pharmacology
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Summary:Lactococcus lactis can decrease the redox potential at pH 7 (Eh₇) from 200 to -200 mV in oxygen free Man-Rogosa-Sharpe media. Neither the consumption of oxidizing compounds or the release of reducing compounds during lactic acid fermentation were involved in the decrease in Eh₇ by the bacteria. Thiol groups located on the bacterial cell surface appear to be the main components that are able to establish a greater exchange current between the Pt electrode and the bacteria. After the final Eh₇ (-200 mV) was reached, only thiol-reactive reagents could restore the initial Eh₇ value. Inhibition of the proton motive force showed no effect on maintaining the final Eh₇ value. These results suggest that maintaining the exofacial thiol (-SH) groups in a reduced state does not depend on an active mechanism. Thiol groups appear to be displayed by membrane proteins or cell wall-bound proteins and may participate in protecting cells against oxidative stress.
ISSN:1742-464X
1742-4658
DOI:10.1111/j.1742-4658.2010.07644.x