Studies on Denitrification

Publisher Website
Google Scholar
Abstract
(1) Pseudomonas denitrificans grew anaerobically using N2O as an electron acceptor (N2O-anaerobically grown cell) in place of oxygen, nitrate or nitrite. Properties of the N2O-anaerobically grown cell were investigated, comparing those of cells grown under various conditions. (2) The N2O-anaerobically grown cell had a high activity of the reduction of N2O to N2, that is, about 1.3 times as high as that of the anaerobically grown cell with nitrate (NO3--anaerobically grown cell). The N2O-anaerobically grown cell possessed also the activity of nitrite reduction and NO reduction, but both activities were only 10 percent or less of that of the NO3--anaerobically grown cell. More than 90 percent of the product of nitrite reduction was found to be NO. (3) The development of the N2O-reducing system was repressed by a high tention of oxygen. The system, however, was induced even in the absence of exogenous N2O, simply under the low-aerobic condition. Possibly the induction may be related to the presence of nitrate ion as the contaminant at the concentration of at most 10−6 M in the medium and to the practically anaerobic condition. The properties of the low-aerobically grown cell were very similar to those of the N2O-anaerobically grown cell. (4) In comparison with the NO3--anaerobically grown cell, soluble CO-binding cytochrome c-553 and particulate-bound cytochrome c-552 were contained in the N2O-anaerobically grown cell about 3 times and 1.8 times as much, respectively. The amounts of cryptocytochrome c and cytochrome b were almost the same as those in the NO3--anaerobically grown cell. (5) The content of “denitrifying enzyme” (nitrite reductase) in the N2O-anaerobically grown cell was only 1/5–1/3 and that of blue protein was almost the same as that in the NO3--anaerobically grown cell, respectively.

This publication has 0 references indexed in Scilit: