Acetylene inhibition of nitrous oxide reduction by denitrifying bacteria

Acetylene (0.1 atm) caused complete or almost complete inhibition of reduction of N₂O by whole cell suspensions of Pseudomonas perfectomarinus, P. aeruginosa and Micrococcus denitrificans. Acetylene did not inhibit reduction of NO₃^? or NO₂^? by these organisms. In the presence of acetylene there was stoichiometric conversion of NO₃^? or NO₂^? to N₂O with negligible subsequent reduction of the latter. In the absence of acetylene there was no or only transient accumulation of N₂O. The data are consistent with the view that N₂O is an obligatory intermediate in the reduction of NO₂^? to N₂ in all of the three organisms studied.