Regulation of enzyme synthesis in Hyphomicrobium X: Growth on mixtures of methylamine and ethanol in continuous cultures

Hyphomicrobium X was grown on a range of mixtures of methylamine and ethanol at various dilution rates in continuous cultures. It was shown that both substrates were utilized simultaneously at all dilution rates below μmax ethanol, the biomass being the sum of the biomass obtained during growth on the single substrates alone. No evidence was observed for a redistribution of the carbon-flow nor the ability to utilize the ‘poorer’ growth substrate-ethanol, at dilution rates greater than μmax ethanol. Work is presented which suggests that the assimilatory pathway enzymes for either the C1- or the C2-compound are regulated coordinately, but separately from the dissimilatory pathway enzymes associated with that compound.