Oxidative and assimilative enzyme activities in continuous cultures of the obligate methylotrophMethylobacillus flagellatum

In methanol-limited continuous cultures of the obligate methylotrophic bacteriumMethylobacillus flagellatum grown at rates from 0.05 to 0.63 h^-1, and also in an oxyturbidostat culture ofM. flagellatum growing at the rate of 0.73 h^-1, levels of methanol dehydrogenase, enzymes of formaldehyde oxidation (both linear and cyclic) and assimilation (RuMP cycle), a number of intermediary metabolism and TCA cycle enzymes and also dye-linked formaldehyde dehydrogenase were determined. It was shown that the activities of dissimilatory enzymes, with the exception of dye-linked formaldehyde dehydrogenase, decreased with increasing growth rate. Activities of assimilative enzymes and activities of the TCA cycle enzymes detected as well as the dye-linked formaldehyde dehydrogenase activity, increased with increasing growth rate. A periplasmic location was shown for the latter enzyme and a role in formaldehyde detoxification was proposed.