On methylamine assimilation in a bacterium

Metabolism of Propane, n -Propylamine, and Propionate by Hydrocarbon-Utilizing Bacteria

Studies were conducted on the oxidation and assimilation of various three-carbon compounds by a gram-positive rod isolated from soil and designated strain R-22. This organism can utilize propane, propionate, or n -propylamine as sole source of carbon and energy. Respiration rates, enzyme assays, and 14 CO 2 incorporation experiments suggest that propane is metabolized via methyl ketone formation; propionate and n -propylamine are metabolized via the methylmalonyl-succinate pathway. Isocitrate lyase activity was found in cells grown on acetate and was not present in cells grown on propionate or n -propylamine. 14 CO 2 was incorporated into pyruvate when propionate and n -propylamine were oxidized in the presence of NaAsO 2 , but insignificant radioactivity was found in pyruvate produced during the oxidation of propane and acetone. The n -propylamine dissimilatory mechanism was inducible in strain R-22, and amine dehydrogenase activity was detected in cells grown on n -propylamine. Radiorespirometer and 14 CO 2 incorporation studies with several propane-utilizing organisms indicate that the methylmalonyl-succinate pathway is the predominant one for the metabolism of propionate.

Oxidation of C-1 compounds by Pseudomonas sp. MS

Pseudomonas sp. MS is capable of growth on a number of compounds containing only C(1) groups. They include trimethylsulphonium salts, methylamine, dimethylamine and trimethylamine. Although formaldehyde and formate will not support growth they are rapidly oxidized by intact cells. Methanol neither supports growth nor is oxidized. A particulate fraction of the cell oxidizes methylamine to carbon dioxide in the absence of any external electron acceptor. Formaldehyde and formate are more slowly oxidized to carbon dioxide by the particulate fraction, although they do not appear to be free intermediates in the oxidation of methylamine. Soluble NAD-linked formaldehyde dehydrogenase and formate dehydrogenase are also present. The particulate methylamine oxidase is induced by growth on methylamine, dimethylamine and trimethylamine, whereas the soluble formaldehyde dehydrogenase and formate dehydrogenase are induced by trimethylsulphonium nitrate as well as the aforementioned amines.