Denitrification of Nitrate by the Fungus Cylindrocarpon tonkinense(Biochemistry & Molecular Biology)

概要

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The denitrifying fungus Cylindrocarpon tonkinense was thought to be able to denitrify only nitrite (NO^-_2) but not nitrate (NO^-_3) to form nitrous oxide (N_2O). Here we found, however, that C. tonkinense can denitrify NO^-_3 under certain conditions. Presence of ammonium (NH^+_3) in addition to NO^-_3 and the use of a fermentable sugar as an electron donor were key conditions for inducing the denitrifying activity. Such induction accompanied a remarkable increase in the intracellular level of the enzyme activities related to NO^-_ 3metabolism. These activities contained assimilatory type NADPH (or NADH) -dependent NO^-_3 reductase (aNar), dissimilatory nitrite reductase (dNir), and nitric oxide reductase (P450nor), but did not contain ubiquinoldependent, dissimilatory NO^-_3 reductase (dNar). The denitrification was inhibited by tungstate, an inhibitor of Nar. These results demonstrated occurrence of a novel type of denitrification in C. tonkinense, in which assimilatory type Nar is possibly involved.
社団法人日本農芸化学会の論文
2003-05-23