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Int. J. Mol. Sci. 2019, 20(3), 782;

The Chemical Transformation of the Cellular Toxin INT (2-(4-Iodophenyl)-3-(4-Nitrophenyl)-5-(Phenyl) Tetrazolium Chloride) as an Indicator of Prior Respiratory Activity in Aquatic Bacteria

Facultad de Ciencias Marinas. UABC, Carretera Tijuana-Ensenada km 106, Ensenada, Baja California, CP 22860, Mexico
CICESE, Carretera Tijuana-Ensenada No. 3918, Ensenada, Baja California, CP 22860, Mexico
Author to whom correspondence should be addressed.
Received: 13 January 2019 / Revised: 2 February 2019 / Accepted: 10 February 2019 / Published: 12 February 2019
(This article belongs to the Special Issue Cell Targets and Toxicity)
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In the ocean, the prokaryote respiration rates dominate the oxidation of organics, but the measurements may be biased due to pre-incubation size filtration and long incubation times. To overcome these difficulties, proxies for microbial respiration rates have been proposed, such as the in vitro and in vivo estimation of electron transport system rates (ETS) based on the reduction of tetrazolium salts. INT (2-(4-Iodophenyl)-3-(4-Nitrophenyl)-5-(Phenyl) Tetrazolium Chloride) is the most commonly applied tetrazolium salt, although it is toxic on time scales of less than 1 h for prokaryotes. This toxicity invalidates the interpretation of the rate of in vivo INT reduction to formazan as a proxy for oxygen consumption rates. We found that with aquatic bacteria, the amount of reduced INT (F; µmol/L formazan) showed excellent relation with the respiration rates prior to INT addition (R; O2 µmol/L/hr), using samples of natural marine microbial communities and cultures of bacteria (V. harveyi) in batch and continuous cultures. We are here relating a physiological rate with the reductive potential of the poisoned cell with units of concentration. The respiration rate in cultures is well related to the cellular potential of microbial cells to reduce INT, despite the state of intoxication. View Full-Text
Keywords: prokaryotes; respiration; INT toxicity prokaryotes; respiration; INT toxicity

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Villegas-Mendoza, J.; Cajal-Medrano, R.; Maske, H. The Chemical Transformation of the Cellular Toxin INT (2-(4-Iodophenyl)-3-(4-Nitrophenyl)-5-(Phenyl) Tetrazolium Chloride) as an Indicator of Prior Respiratory Activity in Aquatic Bacteria. Int. J. Mol. Sci. 2019, 20, 782.

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