Stimulatory Effect of Xenobiotics on Oxidative Electron Transport of Chemolithotrophic Nitrifying Bacteria Used as Biosensing Element |
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| Authors: | Andrzej Woznica Agnieszka Nowak Przemyslaw Ziemski Miros?aw Kwasniewski Tytus Bernas |
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| Institution: | 1. Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia, Katowice, Poland.; 2. Department of Genetics, Faculty of Biology and Environmental Protection, University of Silesia, Katowice, Poland.; 3. Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warszawa, Poland.; Institut Pasteur Paris, France, |
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| Abstract: | Electron transport chain (ETCh) of ammonium (AOB) and nitrite oxidizing bacteria (NOB) participates in oxidation of ammonium to nitrate (nitrification). Operation of ETCh may be perturbed by a range of water-soluble xenobiotics. Therefore, consortia of nitrifying bacteria may be used as a biosensor to detect water contamination. A surprising feature of this system is an increase of oxygen consumption, detected in the presence of certain inhibitors of ETCh. Thus, to shed light on the mechanism of this effect (and other differences between inhibitors) we monitored separately respiration of the bacteria of the first (AOB - Nitrosomonas) and second (NOB -Nitrobacter) stages of nitrification. Furthermore, we measured plasma membrane potential and the level of reduction of NAD(P)H. We propose a novel model of ETCh in NOB to explain the role of reverse electron transport in the stimulation of oxygen consumption (previously attributed to hormesis). |
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