Table 1.

Hydrogenase activity of Edwardsiella tarda under different conditions.

Growth condition	Hydrogenase activity (μmol of H2/min/109 cells)a
	TX01	TX01Δsip2	TX01Δsip2/sip2
pH 7	2.1 ± 0.01	0.13 ± 0.04∗∗	2.22 ± 0.03
pH 6	0.46 ± 0.05	0.14 ± 0.04∗∗	0.49 ± 0.03
Iron-depletion	0.31 ± 0.03	0.24 ± 0.02∗	0.36 ± 0.03

^aValues are means ± standard deviations of the results for three replicate assays. ^∗∗P < 0.01; ^∗P < 0.05. Significance was determined between the wild type and the mutant/complement strain.