[Diauxotrophic properties of microorganisms assimilating C2--C4 hydrocarbons]

Diauxotrophic properties of bacteria assimilating gaseous hydrocarbons C2--C4 and other complex organic substances but not methane were studied. If the medium contained two substrates (hydrocarbon+carbohydrate), the non-growing cells of the strains did not display diauxotrophic properties. In the phase of exponential growth, oxygen-containing carbon sources and then gaseous hydrocarbons were assimilated, i.e. diauxia was observed. If a microbial association containing an obligate methylotroph and a facultative gas-assimilating culture was grown on a medium with a natural gas, the latter culture assimilated carbon-containing metabolites of the methylotroph and then, when their concentration decreased, gaseous hydrocarbons. The order in which complex organic substances (exometabolites of methylotrophs) and hydrocarbons C2--C4 were assimilated was determined by their concentration in the medium. In the course of growth of such a microbial association, the inhibiting effect of metabolites of methylotrophs on their growth decreased as well as the loss of methane being transformed by methylotrophs into exometabolites, and hydrocarbons C2--C4 were utilized.