Studies on bacterial activities during degradation of mineral oil compounds

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MORASCH, Barbara, 2003. Studies on bacterial activities during degradation of mineral oil compounds

@phdthesis{Morasch2003Studi-7690, title={Studies on bacterial activities during degradation of mineral oil compounds}, year={2003}, author={Morasch, Barbara}, address={Konstanz}, school={Universität Konstanz} }

application/pdf Untersuchungen zur bakteriellen Aktivität im Zuge des Abbaus von Mineralölkomponenten 2011-03-24T17:36:25Z Morasch, Barbara 2003 Studies on bacterial activities during degradation of mineral oil compounds deposit-license Morasch, Barbara 1. Adsorber resin Amberlite-XAD7 was applied in bacterial batch cultures to enrich, isolate, and cultivate bacteria that use putatively toxic substrates.<br />2. Strain OX39, isolated from contaminated aquifer material in the presence of XAD7, is an endospore-forming sulfate-reducing bacterium. Its substrate range was found to be limited to toluene, m- and, o-xylene, as well as their degradation products benzoic acid, m-, and o-toluic acid. Degradation to CO2 proceeds via fumarate addition to one methyl group. Analysis of its 16S rRNA gene showed that strain OX39 is the first aromatic hydrocarbon-using member of the genus Desulfotomaculum.<br />3. For measurement of 2H/1H isotope fractionation upon bacterial toluene degradation, an alternative approach by gas chromatographic analysis was developed. Selectively deuterium labeled toluene species were supplied as growth substrates. Results acquired could be validated using IRM-GC-MS.<br />4. Carbon and hydrogen isotope fractionation during toluene degradation were found to be independent of growth temperatures under sulfate-reducing conditions. In contrast, during aerobic toluene degradation by P. putida strain mt-2, isotope fractionation was found to vary with growth temperatures. Isotope fractionation was not influenced by degradation rates.<br />5. Isotope enrichment factors for toluene determined in growth experiments with bacterial pure cultures taking nitrate, Fe(III), or sulfate as electron acceptors were close to each other. Significantly higher isotope enrichment was observed under oxic conditions. Therefore, important prerequisites for quantification of contaminant degradation in situ might be fulfilled only in absence of O2.<br />6. The main process leading to isotope fractionation during toluene degradation was the first enzyme reaction, whereas substrate diffusion to the cells and substrate uptake by the bacteria was negligible. Influence of additional masses by deuterium labels was not detectable.<br />7. Various bacteria degrading different substrates in enzyme reactions of the glycyl radical type caused isotope enrichment in a narrow range. An average enrichment factor may be applicable to quantify overall biodegradation of contaminants degraded via this pathway in the environment.<br />8. Aerobic degradation of different methyl benzenes via a methyl monooxygenase reaction was accompanied by large isotope enrichment effects. Mono- and dioxygenase reactions attacking the aromatic ring led to characteristically weak or insignificant hydrogen and carbon isotope fractionation. The big differences preclude quantitative applications in oxic environments. However, isotope shifts are positive indications for in situ biodegradation. 2011-03-24T17:36:25Z eng

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