MICR30030

The lecture course provides the keys to the vast subject of bacterial metabolism. Bacteria use diverse strategies to capture energy and build new cellular materials. The most efficient energy transduction systems involve electron flow from a donor to a terminal acceptor through membrane-embedded transport chains. The free energy released is used to establish gradients of protons across membranes. The resulting protonmotive force can be used to do useful work such as ATP synthesis, active transport of solutes, or flagellar rotation. Bacteria use three external energy sources to generate protonmotive force: phototrophs use light whereas lithotrophs and organotrophs oxidise inorganic and organic fuels respectively. In circumstances where generation of ion gradients is not possible, organotrophs can obtain energy inefficiently by partial breakdown (fermentation) of organic compounds.
As well as explaining bacterial energy transduction, the course will cover the main metabolic pathways for biosynthesis of new cellular materials and breakdown of organic substrates. These include synthesis of sugars from carbon dioxide, glycolysis, the citric acid cycle, the pentose phosphate pathway, biosynthesis and beta-oxidation of fatty acids, biosynthesis of amino acids and nucleotides. Under anaerobic conditions, specialised groups of bacteria use carbon dioxide and molecular hydrogen to synthesise acetate (acetogenesis) or methane (methanogenesis). The lectures will explain how and why these two processes occur.

The practical component will include disruption of bacterial cells, fractionation of lysates by differential centrifugation, analysis of subcellular fractions by colorimetric assays, and analysis of Gram-negative outer membrane proteins by SDS-polyacrylamide gel electrophoresis.