FIG. 2.

N₂O uptake by free-living cells of the nosZ mutant (A) and nos complementation of USDA110ΔnosZ (B) and T7 (C). pKS800 is the cosmid vector used for complementation (17). Two cosmid clones, brc02856 and brc01733, have inserts containing nos genes of USDA110 (Table 1; Fig. 1). N₂O reductase activities (means ± SDs) estimated from maximum rates of N₂O uptake were 4.6 ± 0.2 [USDA110(pKS800)], 22.9 ± 0.7 [USDA110ΔnosZ(brc02856)], and 23.6 ± 1.9 N₂O [USDA110ΔnosZ(brc01733)] μmol h⁻¹ 10⁷ cells⁻¹.