TABLE 1.

Compilation of published kinetic isotope effects of AOA and AOB.

Source	AOA/AOB	Strain	Initial [NH4+] (mM)	Other conditions	εRS		εCP
					Mean	SD	Mean	SD
This study	AOA	Nitrosopumilus adriaticus NF5	1		32.1	1.0	40.1	0.7
	AOA	Nitrososphaera viennensis EN76	1		31.9	1.2	37.7	0.8
	AOA	Nitrososphaera viennensis EN76	2		33.1	0.7	39.0	1.2
Santoro and Casciotti (2011)	AOA	Marine AOA enrichment CN25†	0.01–0.075				22	5
		Marine AOA enrichment CN75					21	10
		Marine AOA enrichment CN150					22	5
Nishizawa et al. (2016)	AOA	Candidatus Nitrosocaldus sp.	0.2				22.0	5.0
		Candidatus Nitrosocaldus sp.	14				24.7	2.1
Mariotti et al. (1981)	AOB	Nitrosomonas europaea	4.7–25		34.7	2.5	31.9	6.4
Delwiche and Steyn (1970)	AOB	Nitrosomonas europaea					26.0	5.6
Yoshida (1988)	AOB	Nitrosomonas europaea	38	pO2 low			24.6
	AOB	Nitrosomonas europaea	38	pO2 medium			29.0
	AOB	Nitrosomonas europaea	38	pO2 high			32.0
Casciotti et al. (2003)	AOB	Nitrosomonas marina	2				14.2	3.6
		Nitrosomonas sp. C-113a	2				19.1	1.2
		Nitrosospira tenuis	1				24.6	1.4
		Nitrosomonas eutropha	1				32.8	1.7
		Nitrosomonas europaea	1				38.2	1.6
Casciotti et al. (2010)	AOB	Nitrosomonas sp. C-113a	0.005–0.05				30–46
	AOB	Nitrosococcus oceani	0.005–0.05				30–46
	AOB	Nitrosospira briensis	0.005–0.05				30–46

^†Currently designated as Candidatus Nitrosopelagicus brevis CN25 (Santoro et al., 2015).