stimulate the oxidation of CO and attempts to grow NH 4 oxidizers on CO as the sole
source of carbon and energy failed.
Figure 2 : Time course of CO oxidation by Nitrosomonas sp. 4W30. Oxidation is expressed as nanomoles per
hour per 25 ml at a cell concentration of 10 6 /ml.
Symbols :
O, 0.0 mg/LNH 4 N.
•, 10 mg/L NH 4 N.
Organism
Source
Carbon monoxide oxidation rate
(DPM)*
14 CO 2 produced
14 C incorporated
into cells
Nilrosococcus oceanus
Marine,
North Atlantic
31565
0
Nitrosomonas europaea
Soil
36888
N. sp. 4W30
Marine,
Alaskan coast
110256
3
N. sp. 1S10
Estuarine,
Florida coast
23431
10
N. sp 2S0
Freshwater,
Louisiana marsh
28834
0
N. sp 6S30
Marine,
Alaskan coast
36561
2
N. sp. 9WO
Freshwater,
Oregon coast
17205
0
N. sp. 3S30
Marine,
Oregon coast
21762
0
N. sp. 11W30
Marine,
Oregon coast
17327
3
Nitrobacter sp. Nb 297
Marine
9
6
Nitrococcus mobilis
Marine,
South Pacific
1
0
Table 4 : Carbon monoxide oxidation by nitrifiers in the absence of ammonium
* CO oxidation rate is expressed as DPM 14 C per 5 ml of cells and filters per 3 h.
The ability of nitrifieres to oxidize CO in the presence and absence of N-serve (2-chloro-6(trichloromethyl) pyridine) was determined (Jones and Morita, 1984). It was found that
100 mg/1 of N-serve would inhibit CO oxidation and this N-serve sensitive CO oxidation
was related to the rate of ammonium oxidation and a detailed description of the method is
given in Jones et al. (Jones, Morita, and Griffiths, 1984). The oxidation of CO is linear
within the time range of test (3 to 6 h). Blockage of CO oxidation is complete with 100
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