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You searched for subject:(xenobiotic degradation). Showing records 1 – 3 of 3 total matches.

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Washington University in St. Louis

1. Campbell, Tayte Paul. Multi-omic Understanding of the Evolution of Xenobiotic Tolerance in Bacterial Isolates and Communities.

Degree: PhD, Biology & Biomedical Sciences (Plant & Microbial Biosciences), 2019, Washington University in St. Louis

Xenobiotic compounds are any chemicals that are released into an environment by human action and that occur at concentrations higher than found naturally. Xenobiotics, including aromatic compounds and antibiotics, are recalcitrant to degradation because they are often toxic or mutagenic. Despite this toxicity, bacteria account for a large portion of xenobiotic degradation in the environment. Bacteria are able to adapt to these foreign chemicals, gaining increased levels of tolerance and increased rates of xenobiotic degradation. On the strain level, increased tolerance can be caused by mutations in individual cells or through the acquisition of genes from other cells. At the community level, xenobiotics select for naturally resistant bacterial often resulting in an increase in genes involved with xenobiotic tolerance. The goal of my thesis was to (1) understand how bacterial strains evolve increased tolerance to toxic aromatics xenobiotics through adapted evolution and (2) how microbial communities in mammalian guts are altered due to xenobiotic selection pressure.To determine the microbial adaptations that occur in bacterial strains exposed to xenobiotics, I studied the changes that occurred in the genome and transcriptome of Rhodococcus opacus PD630 when grown over several generations on increasing concentrations of toxic aromatic compounds. Chemical pretreatment of lignocellulose as a first step in biofuel production results in the creation of monomeric sugars and toxic xenobiotic compounds. Bacterial conversion of the resulting moiety to biofuel precursors is one of the most cost-effective methods of biofuel production. However, the toxic aromatic compounds created from lignocellulose pretreatment inhibit bacterial growth and reduce overall productivity. R. opacus is a bacterial strain that naturally has a high tolerance to aromatic compounds and optimization of this bacteria can improve process efficiency. By analyzing 35 R. opacus strains adapted on 6 different compounds or compound mixtures, I show that adapted strains demonstrated up to 1900% improvement in final cell densities. I found no mutations in xenobiotic degradations genes for the adapted strains, but I found several mutations in genes that are involved with oxidation-reduction reactions that may assist in degradation. These results demonstrate that bacterial strains can gain increased xenobiotic tolerance by fine-tuning metabolic pathways indirectly related to xenobiotic degradation.To determine the effects of xenobiotic selection on microbial communities, I studied the gut microbiome of humans, captive chimpanzees, and captive gorillas that have received antibiotic treatment compared to the microbiome of wild chimpanzees and gorillas that have never received antibiotic treatment. I found that antibiotic treatment was correlated with higher richness and abundance of antibiotic resistance genes. In addition, the microbiome and resistome in captive apes were more similar to that of humans than to the wild apes, despite differences in host species… Advisors/Committee Members: Gautam Dantas, Arpita Bose, Andrew Kau, Audrey Odom-John, Himadri Pakrasi.

Subjects/Keywords: antibiotic resistance, bacterial communities, genomics, lignocellullose degradation, metagenomics, xenobiotic tolerance; Bioinformatics; Biology; Microbiology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Campbell, T. P. (2019). Multi-omic Understanding of the Evolution of Xenobiotic Tolerance in Bacterial Isolates and Communities. (Doctoral Dissertation). Washington University in St. Louis. Retrieved from https://openscholarship.wustl.edu/art_sci_etds/1888

Chicago Manual of Style (16th Edition):

Campbell, Tayte Paul. “Multi-omic Understanding of the Evolution of Xenobiotic Tolerance in Bacterial Isolates and Communities.” 2019. Doctoral Dissertation, Washington University in St. Louis. Accessed October 26, 2020. https://openscholarship.wustl.edu/art_sci_etds/1888.

MLA Handbook (7th Edition):

Campbell, Tayte Paul. “Multi-omic Understanding of the Evolution of Xenobiotic Tolerance in Bacterial Isolates and Communities.” 2019. Web. 26 Oct 2020.

Vancouver:

Campbell TP. Multi-omic Understanding of the Evolution of Xenobiotic Tolerance in Bacterial Isolates and Communities. [Internet] [Doctoral dissertation]. Washington University in St. Louis; 2019. [cited 2020 Oct 26]. Available from: https://openscholarship.wustl.edu/art_sci_etds/1888.

Council of Science Editors:

Campbell TP. Multi-omic Understanding of the Evolution of Xenobiotic Tolerance in Bacterial Isolates and Communities. [Doctoral Dissertation]. Washington University in St. Louis; 2019. Available from: https://openscholarship.wustl.edu/art_sci_etds/1888


Université du Luxembourg

2. Christen, Anne. The impact of macro-substrate on micropollutant degradation in activated sludge systems.

Degree: 2019, Université du Luxembourg

Wastewater treatment plants are designed as a first barrier to reduce xenobiotic emission into rivers. However, they are not sufficient enough to fully prevent environmental harm of emerging substances in the water body. Therefore, advanced treatment processes are currently being investigated but their implementation is cost-intensive. The optimisation of the activated sludge treatment to enhance biological micropollutant removal could reduce operating costs and material. Although the impact of operational parameters, such as sludge retention time and hydraulic retention time on the xenobiotic removal have been investigated, the influence of the macro-substrate composition and load on micropollutant elimination causes a high degree of uncertainty. This study focuses on the latter by analysing 15 municipal wastewater treatment plants, where variations in load and composition of the macro-substrate were expected. Assuming that macro-substrate shapes the biomass and triggers their activity, the impact of macro-substrate composition and load on xenobiotic degradation by microorganisms was analysed. It was hypothesised that on the one hand, a high dissolved organic carbon concentration might lead to enhanced xenobiotic degradation for certain substances due to a high microbial activity. The latter is assumed to be caused by a high labile dissolved organic carbon portion and the tendency for a shorter sludge retention time. On the other hand, a low dissolved organic carbon concentration, probably containing a predominant recalcitrant substrate portion, tends to a longer sludge retention time. Consequently, slow-growing and specialised microorganisms may develop, able to degrade certain xenobiotics. As a second question, the contribution of the autotrophic biomass to xenobiotic degradation was tested by inhibiting the autotrophic microorganisms during the degradation test. To additionally test the hypothesis, the impact of a readily biodegradable substrate (acetate) on the xenobiotic degradation was tested and the sensitivity of the fluorescence signal of tryptophan was used to analyse the impact of tryptophan on xenobiotic degradation. Degradation tests focusing on the removal of macro-substrate and micropollutants within 18 hours incubation in the OxiTop® system were performed. The OxiTop® system is known as fast and easy method for organic matter analysis in the wastewater. To assess the macro-substrate composition prior to and after the degradation test, three characterisation methods were applied. Firstly, to determine the labile and the rather recalcitrant portion in the dissolved organic carbon, absorbance was measured at 280 nm and further analysed. This was verified by the characterisation of both portions based on the oxygen consumption measurements. Secondly, to analyse the organic matter concerning its fluorescent properties, excitation-emission scans were run and analysed using the parallel factor analysis approach. Lastly, the chromophoric and fluorescent organic matter was separated via size-exclusion… Advisors/Committee Members: Hansen, Joachim [superviser], Wilmes, Paul [president of the jury], Köhler, Christian [member of the jury], Abbt-Braun, Gudrun [member of the jury], Knerr, Henning [member of the jury].

Subjects/Keywords: micropollutants; macro-substrate; xenobiotic degradation; Engineering, computing & technology :: Civil engineering [C04]; Ingénierie, informatique & technologie :: Ingénierie civile [C04]

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Christen, A. (2019). The impact of macro-substrate on micropollutant degradation in activated sludge systems. (Doctoral Dissertation). Université du Luxembourg. Retrieved from http://orbilu.uni.lu/handle/10993/41195

Chicago Manual of Style (16th Edition):

Christen, Anne. “The impact of macro-substrate on micropollutant degradation in activated sludge systems.” 2019. Doctoral Dissertation, Université du Luxembourg. Accessed October 26, 2020. http://orbilu.uni.lu/handle/10993/41195.

MLA Handbook (7th Edition):

Christen, Anne. “The impact of macro-substrate on micropollutant degradation in activated sludge systems.” 2019. Web. 26 Oct 2020.

Vancouver:

Christen A. The impact of macro-substrate on micropollutant degradation in activated sludge systems. [Internet] [Doctoral dissertation]. Université du Luxembourg; 2019. [cited 2020 Oct 26]. Available from: http://orbilu.uni.lu/handle/10993/41195.

Council of Science Editors:

Christen A. The impact of macro-substrate on micropollutant degradation in activated sludge systems. [Doctoral Dissertation]. Université du Luxembourg; 2019. Available from: http://orbilu.uni.lu/handle/10993/41195


University of Cincinnati

3. Subramanian, Venkataramanan. Functional Genomics of Xenobiotic Detoxifying Fungal Cytochrome P450 System.

Degree: PhD, Medicine : Toxicology (Environmental Health), 2008, University of Cincinnati

The white rot fungus <i>Phanerochaete chrysosporium</i>is primarily known for its ability to degrade a wide range of xenobiotic compounds including the highly recalcitrant polycyclic aromatic hydrocarbons. The natural substrate of this basidiomycete fungus is however, lignin, the most abundant aromatic polymer on earth. The versatililty of this fungus in breaking down a wide array of compounds arises from the presence of a highly nonspecific enzyme system (peroxidase enzyme system) in its repertoire. Most of the research involving degradation of toxic chemicals has focused on this biodegrading enzyme machinery. Cytochrome P450 monooxygenases (P450s) on the other hand, are heme-thiolate proteins that are known to be involved in metabolism of endogenous compounds as well as xenobiotic compounds in higher eukaryotes. Nearly 150 P450s are present in this organism, which is the highest number known till date among fungal species. Based on the sequence similarity criteria and our phylogenetic analysis, these P450s have been classified under 12 families and 23 sub-families. Despite indirect evidences suggesting the role of P450s in oxidation of xenobiotics, there have been hardly any reports on characterization and role of individual P450s either in regulation of physiological processes or in direct metabolism of xenobiotics in this organism. Here we characterized and investigated the role of P450 enzymes in two different mechanisms in this fungus. One, indirect involvement of P450s in peroxidase–mediated oxidation of xenobiotics, and two, direct involvement of P450s in metabolism of xenobiotics. In order to achieve the first objective, we investigated the role of <i>PC-bph</i>gene, the only member of the P450 CYP53 in synthesis of a secondary metabolite, veratryl alcohol, which regulates the activity of the peroxidase enzyme system of this fungus. In order to achieve the second objective, we used the functional genomic approach based on a custom-designed microarray and heterologous expression of the components of the P450 enzyme system (P450 and its associated electron transfer proteins) in this white rot fungus. Advisors/Committee Members: Yadav, Dr. Jagjit (Advisor).

Subjects/Keywords: <; i>; Phanerochaete chrysosporium<; /i>;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Subramanian, V. (2008). Functional Genomics of Xenobiotic Detoxifying Fungal Cytochrome P450 System. (Doctoral Dissertation). University of Cincinnati. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204753142

Chicago Manual of Style (16th Edition):

Subramanian, Venkataramanan. “Functional Genomics of Xenobiotic Detoxifying Fungal Cytochrome P450 System.” 2008. Doctoral Dissertation, University of Cincinnati. Accessed October 26, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204753142.

MLA Handbook (7th Edition):

Subramanian, Venkataramanan. “Functional Genomics of Xenobiotic Detoxifying Fungal Cytochrome P450 System.” 2008. Web. 26 Oct 2020.

Vancouver:

Subramanian V. Functional Genomics of Xenobiotic Detoxifying Fungal Cytochrome P450 System. [Internet] [Doctoral dissertation]. University of Cincinnati; 2008. [cited 2020 Oct 26]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204753142.

Council of Science Editors:

Subramanian V. Functional Genomics of Xenobiotic Detoxifying Fungal Cytochrome P450 System. [Doctoral Dissertation]. University of Cincinnati; 2008. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204753142

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