THE INFLUENCE OF PRESSURE ON THE GROWTH OF METHANOTROPHIC BACTERIA

The growth rate and the maximum cell concentration of methanotrophic b acteria are limited by the transfer of methane and oxygen to the cultu re fluid. The operation under moderate pressure results in an increase in driving force for the mass transfer of both nutrients and, therefo re, in a large increase in the attainable biomass concentration. Our l aboratory pressure fermenter with a volume of 12 litres operates under a system pressure of up to 0.5 MPa. In this reactor a maximum product ivity of 6 g biomass/lh is achieved. However, operating under moderate system pressure and exhaust gas recycling has also disadvantages beca use the concentrations of the gas phase components may inhibit the gro wth process. From the results of the laboratory fermenter we have deve loped kinetic models of the influence of dissolved oxygen and carbon d ioxide on the specific growth rate of the methanotrophic strain GB 25. These models are the basis for processing under increased system pres sure and exhaust gas recycling.