Full text loading...
Methylamine Uptake by the Facultative Methylotroph Hyphomicrobium X
Abstract
Hyphomicrobium X grows on methylamine as sole source of carbon, energy and nitrogen. The uptake of the compound occurred via a single inducible transport system irrespective of whether methylamine was used as a carbon and energy source or a nitrogen source only. The transport system had the following properties: temperature optimum 30 °C, pH optimum 7·0, K m approx. 70–100 nm, V max 12·5 nmol min−1 (mg dry weight)−1. Methylamine uptake was inhibited by azide, cyanide, N-ethylmaleimide and carbonyl cyanide-m-chlorophenyl-hydrazone. The uptake was not inhibited by ammonium ions, was slightly inhibited by amino acids and amides but was competitively inhibited by short-chain alkylamines (K i ethylamine 200 nm). Cells grown on formate, methanol or ethanol as C-source and ammonium sulphate as N-source did not possess the transport system but this could be induced by the presence of methylamine for 45–50 min. The addition of formate, methanol or ethanol to methylamine-grown cells did not affect the rate of methylamine uptake. Bacteria pre-grown on dimethylamine or trimethylamine transported methylamine into the cells at rates of 99% and 52%, respectively, when compared to rates with cells pre-grown on methylamine.
- Received:
- Revised:
- Published Online:
© Society for General Microbiology 1984