ITQB: BEM - MA Dissertations
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- Study of the QrcABCD membrane complex involved in energy conservation in gut anaerobesPublication . Manteigas, Gonçalo; Cardoso Pereira, Inês; Duarte, Américo"The human gut microbiome has been studied for several decades, and changes in its composition affect human physiology and may trigger health disorders. Sulfate-reducing prokaryotes (SRP) are members of this diverse microbiota and are implicated in inflammatory bowel diseases (IBD) and in colorectal cancer due to sulfide toxicity, which is released as the main product of their metabolism. In the gut, one of the main electron sources for microbial respiration is hydrogen and SRP can use it to respire sulfate producing sulfide. The QrcABCD is an electrogenic respiratory complex, present in the inner membrane, that is essential to link the periplasmic oxidation of hydrogen to sulfate metabolism inside the cell.(...)"
- Novel Biohybrid Systems for the Production of Solar FuelsPublication . Otega Ojake, Leona; Neves, Mónica; Cardoso Pereira, Inês"Greenhouse gas emissions from the energy sector being one of the major contributors to climate change, the search for clean sustainable fuels and a sustainable means to close the anthropogenic carbon cycle are more pressing than ever. Sunlight provides more energy in a day than humanity requires in a year, thus the conversion of solar energy into fuels is an expanding and highly promising area. Biohybrid photosynthetic systems, coupling whole cell catalysts with semiconductors produced by self-photosensitised non-photosynthetic microorganisms, have emerged as a potential approach for the production of solar fuels in a process known as semi-artificial photosynthesis. The objective of the following work is the creation of novel biohybrid systems using different combinations of microorganisms and semiconductors for the light driven conversion of CO2 into value-added compounds and the sustainable production of hydrogen (H2) fuel.(...)"
- Elucidating the physiological role of the DsrJ cytochrome in dissimilatory sulfate metabolismPublication . Bernardino, Raquel M.; Cardoso Pereira, Inês"The increase of sulfidogenic (sulfide-producing) bacteria in the human gut, as a result of dysbiosis, is often associated with chronic inflammatory disorders. The pathogenesis of sulfidogenic bacteria is mainly due to the toxicity of their main metabolic product, sulfide. To prevent the development of such diseases, it is crucial to understand the energy metabolism of these bacteria. Desulfovibrio vulgaris Hildenborough, a sulfate-reducing bacterium that is a member of the human gut microbiota, is one of the best-studied model organisms for the dissimilatory reduction of sulfate to sulfide. Nonetheless, its energy-conserving mechanisms are still not fully understood, particularly, the function of the widely conserved DsrMKJOP transmembrane complex. The Dsr complex is likely involved in the reduction of the DsrC-trisulfide with the concomitant production of sulfide, through the DsrMK module. However, the function of the DsrJOP module is more puzzling, namely that of its periplasmic subunit, DsrJ.(...)"
- Influence of Ferredoxin, Iron-Sulfur Carrier and Cobalamin Importer Overexpression on the Production of High-value Products by Escherichia coliPublication . Rebelo Manuel, Rita; Bokinsky, Gregory; Pereira, Inês Cardoso"One of the problems in antibiotics production is the difficulty of their synthesis or low yield in the case of complex biological molecules. They have complex biosynthetic pathways, where cobalamin-dependent SAM enzymes play a pivotal role, with an Fe-S cluster in their structure and the necessity of secondary electron transfer proteins for their activity, making the production improvement difficult. An example of these compounds are fosfomycin (Fom3 enzyme), a broadspectrum antibiotic, and thiostrepton (TsrM enzyme), a Gram-positive antibiotic with anticancer properties, both naturally produced by Streptomyces sp..(...)"
- Insights in dissimilatory sulfite reductase proteinsPublication . Conceição, Sara Cristina Pardal; Pereira, Inês Cardoso; Venceslau, Sofia"Microorganisms present in the gastrointestinal tract (GI) are essential in the digestion and production of enzymes for the degradation of otherwise indigestible polysaccharides. Some of the microorganisms present in the GI belong to the sulfate reducing bacteria group, which reduce sulfate to sulfide. These bacteria are also linked to inflammatory bowel diseases due to the toxic and corrosive effects of the sulfide produced. (...)"
- The Role of DsrC in Dissimilatory Sulfite ReductionPublication . Preto, André Gonçalves Carvalho; Pereira, Inês Cardoso; Venceslau, SofiaStudies involving the human gastrointestinal microbiota and its metabolites have revealed the presence of sulfate-reducing bacteria (SRB) within the gut. These microorganisms have been implicated in inflammatory bowel diseases due to the toxic effects of sulfide, produced during dissimilatory sulfate reduction, leading to cell inflammation. The reduction of sulfite to sulfide is carried out by the dissimilatory sulfite reductase, DsrAB, and also involves the DsrC protein, which is a major protein in the cell and contains two conserved redox-active cysteines in a flexible C-terminal arm. The disulfide bond formed between these two conserved cysteines during sulfite reduction is believed to be reduced by several proteins that are related to the catalytic subunits of the heterodisulfide reductases (Hdr) of methanogens, namely HdrB and HdrD.