Nitric Oxide Production by the Human Intestinal Microbiota by Dissimilatory Nitrate Reduction to Ammonium

Table 1

Nitrogen concentrations measured after 24 hours of anaerobic incubation of fecal microbiota in feed medium supplemented with K¹⁵NO₃ (10 atom %). The N₂ concentration measured in the control is subtracted from the concentrations measured in the samples. ¹⁵NH₄⁺ and organic ¹⁵N are recovered from K¹⁵NO₃ (10 atom %). Results are means ± standard deviation of 3 incubations of fecal suspension from 1 representative person.

	5 mg ^15NO3^−-N/L	50 mg ^15NO3^−-N/L	50 mg ^15NO3^−-N/L abiotic control
Nitrate-N (mg/L)	0	0	41.3±4.5
Nitrite-N (mg/L)	0.1±0.02	0.08±0.01	0.4±0.03
NO-N (ng/L)	111±5^a	215±1^b	2.3±0.4^c
N2O-N (ng/L)	4020±246^a	58553±4837^b	0^c
N2	0	0	—
^15NH4^+ (atom %)	>10	>10	0
Organic ^15N (atom %)	0.05±0.03	0.14±0.03	0

abc significant differences between a, b, and c (𝑃<.05).