Research on Nitrification : Isolation and Suppression of Nitrifing Bacteria

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(1)In spite that it is difficult to prepare 1,3,5-triazines having different substituents, 2,4-bis(trichloromethy1)-6-trifluoromethy 1-1,3,5-triazine and 2-methy 1-4-trichloromethy 1-6-trifluoromethy 1-1,3,5-triazine were synthesized by the condensation reaction between corresponding imidoy 1-amidines and acid anhydrides. Other many of 1,3,5-triazines were synthesized using trimerization reaction and co-trimerization reactions.(2)1,3,5-Triazines having fluorine substituents showed weak nitrification inhibitory activity but 2-amino-4-tribromomethy 1-6-trichloromethy 1-1,3,5-triazine very strongly suppressed the growth of Nitrosomonas europaea ATCC25978 (pI_<50>=7.12). It was 65 times stronger than that of authentic nitrification inhibitor, MAST (pI_<50>=5.31).(3)We made a new ammonia bicarbonate (ABC) medium for the culture of N.europaea ATCC25978. In this medium N.europaea grew 3 times faster than in Lewis & Pramer medium.(4)Attempt to isolate new nitrifying bacteria using ABC medium from soil is not sucessful yet.(5)In the bioassay using N.europaea ATCC25978, N.sp.TK794, Nitorobacter agilis ATCC14123, and N.sp TH21., synthesized 1,3,5-triazines inhibited the growth of genus Nitorosomonas.(6)In the cell free level assay of O_2-consumption by N.europaea using ammonium sulfate as substrates, the target enzyme of synthesized 1,3,5-triazines is found to be an ammonia-monooxygenase.