MODE OF ACTION AND QSAR STUDIES OF NITRIFICATION INHIBITORS - EFFECT OF TRICHLOROMETHYL-1,3,5-TRIAZINES ON AMMONIA-OXIDIZING BACTERIA

The effects of trichloromethyl-1, 3, 5-triazines on the ammonia oxidiz ing activity of the nitrifying bacteria Nitrosomonas europaea ATCC 259 78 and Nitrosomonas sp. TK 794 were investigated. Trichloromethyl-1, 3 , 5-triazines inhibited nitrite production in the ammonia oxidation st ep, but showed no inhibition to the hydroxylamine oxidation step of bo th ATCC 25978 and TK 794. The ammonium oxidation by ATCC 25978 was aff ected more strongly than that by TK 794. These results suggest that th e trichloromethyl-1, 3, 5-triazines may inhibit the ammonia monooxygen ase of Nitrosomonas spp. Quantitative structure activity relations (QS AR) studies were carried out between the nitrification inhibitory acti vity (pI(50)) values on both strains and a hydrophobic parameter (log octanol-water partition coefficient, log P) by means of regression ana lysis. The optimum log P of trichloromethyl-l, 3, 5-triazines for both ATCC 25978 and TK 794 was calculated as about 4.