Research: Rhodopseudomonas palustris is an anoxygenic phototroph that is metabolically versatile. Being able to switch between different modes of metabolism allows for its commercial and industrial application (ex. biodegradation of aromatic compounds from industrial waste; the production of H2 as a by-product of N2 fixation by the enzyme nitrogenase). Recently, a family of nitrogenase-like enzymes called Methylthio-alkane Reductases (Mar), has been a focus of study. In order to make methionine (an important amino acid), Mar enzymes utilize methyl-thio ethanol (MT-EtOH) as a sulfur source, and while it does this, it produces ethylene as a by-product. Ethylene is a volatile organic sulfur compound that has been described to have an effect in soil environments and climate. This compound is an important phytohormone, helping plants handle certain stresses such as pathogens. Other applications of ethylene are that the compound is a precursor to plastics. Additionally, ethylene in its oxidized form is a potent carcinogen. Some bacteria found in the soil or gut microbiome have at least one Mar enzyme, while R. palustris has multiple. The focus for my Ph.D. is to further characterize R. palustris’ Mar isozymes and how they contribute to ethylene production and sulfur-cycling, utilizing genetic and physiological approaches. Additionally, since R. palustris has multiple Mar enzymes, we want to further study and test the hypothesis of these different Mar variants potentially utilizing different metal cofactors similar to the nitrogenase enzymes.
