[Comparative studies of fresh and seawater for the determination of total coliform and fecal coliform bacteria according to the European Economic Community guideline 76/160 (bathing water) by the use of the most-probable-number method with BRILA-MUG broth and differentiation according to the drinking water ordinance].

During the summer season of 1989 about 222 samples of bathing water (Northsea, Baltic Sea and inland waters) were investigated, i.e. 2 times 1998 dilution tubes (1501 positive) were tested. Results with BRILA-MUG and lactose-bouillon were compared and additional 97 samples were tested with one respectively three colonies by confirmative tests. -- The BRILA-MUG one-tube-test (gas, fluorescence and indol) has as expected larger numbers of total coliforms (GC) and faecal coliforms (FC) in comparison with corresponding numbers for E. coli and coliform bacteria according to German law for drinking water (TrinkwV). -- BRILA-MUG and lactose-bouillon with the same identification mode according to "TrinkwV" has corresponding results concerning E. coli and coliform bacteria. -- Following the identification mode according to "TrinkwV" the total coliforms (GC/gas in BRILA-MUG) depending on the origin proved 60-80% as coliform bacteria. Additional API-tests showed that the other bacteria are coliform bacteria too or bacteria which can be considered as indicators for water pollution. -- Faecal coliforms (FC/fluorescence and indol-positive) depending on the origin proved 70-90% as E. coli, if following the identification mode according to "TrinkwV". Using 3 instead of 1 colony per positive dilution tube for identification the positive results increased approximately by 9%. 15% of negative results with the identification mode according to "TrinkwV" proved as E. coli-positive with identification according to API-system, i.e. the corresponding rate of E. coli-positive tubes will therefore be higher than shown above. The BRILA-MUG one-tube-test in connection with the MPN-method can be used successfully to determine the number of total and faecal coliforms according to the EEC-directive for bathing waters. The test needs only a minimum of material and also a minimum of laboratory staff. Differences between this test and other more extensive tests with several biochemical identification steps are negligible. The work load for bathing water tests would not be justified in this case.