[Microbiological studies of groundwater polluted with hydrocarbons. 2. Determination of bacterial in vitro activity].

The injected water and the groundwater withdrawn by the E-wells contained bacteria with higher 'in vitro'-total activity (30-50%) than the groundwater taken from the middle part of the flushing area. The determination of single-activities resulted in a similar distribution of bacterial communities. Denitrifying and nitrate-reducing bacteria were present in the polluted groundwater (10-100% of isolates). After transforming these values in CFU/ml they correspond to the MPN/ml of both groups. Furthermore bacteria were found, which could use hydrocarbons as their only carbon source under aerobic and anaerobic conditions; there were different percentage of hydrocarbon-degrading bacteria in the groundwater of the three sampling points. Totally 2-70% of all isolates were aerobe hydrocarbon-degrading bacteria, 1-12% nitrate-reducing and 1-13% denitrifying hydrocarbon-metabolizing bacteria.