Anàlisi dels principals gens involucrats en el transport d’electrons sota condicions anàlogues a l’electrosíntesi microbiana en S. Ovata

Abstract

Recently, the interest for alternatives to fossil fuels has been increased. One of the alternatives that are investigated is the use of biofuels, which can be produced by electrotrophic microorganisms in a bioelectrochemical system (BES). In BES, bacteria take the reducing power from a cathode to reduce CO2 into organic compounds. One of the most interesting microorganisms in this process is the homoacetogenic Sporomusa ovata, which can produce acetate with a highly efficient production rate. In this work, we aimed at investigating, at the molecular level, what were the most relevant electron carriers to participate in electron transport in inorganic conditions. The general goal of the project were this research was developed was to increase electron capturing by genetic modification and overexpression of relevant candidate genes. We carried out a throughout study of changes in the expression of candidate genes coding for electron-transporter proteins localized at the membrane and the periplasmic space of S. ovata. Specific primers for 27 candidate genes were designed and their specificity was checked through PCR. Changes in the relative expression of those genes (candidate gene/housekeeping gene) were investigated and compared in S. ovata cultures exponentially grown under autotrophic and heterotrophic conditions. Results showed that genes codifying for hydrogenases (e.g. hydA), some ferredoxins (Rnf complex), and c-type cytochromes, were highly transcribed levels in autotrophic conditions. Those genes were postulated as good candidates to capture cathode electrons and would probably be important to be considered in order to optimize S. ovata electron capturing. Due to the poor stabilization of S. ovata cells in the cathode compartment we could not confirm to what extent HydA, Rnf, and Cytochrome c are really participating in electron capturin