[Elimination of nitrous oxide by a combined bacterial culture]

The ability of bacteria to eliminate nitrous oxide (N2O) from a gaseous phase containing 20% O2 was studied. Representatives of the following physiological groups were found to be incapable of removing N2O: denitrifying bacteria (Paracoccus denitrificans), nitrifying bacteria (Nitrosospira briensis), carboxydobacteria (Pseudomonas carboxydoflava), methane oxidizing bacteria (Methylosinus trichosporium), and nitrogen fixing bacteria (Bacillus polymyxa). Five corynebacteria-like strains were isolated from soil samples actively eliminating N2O under oxidative conditions. None of the strains could remove considerable amounts of N2O in pure culture. The rate of N2O elimination was much higher than that of the initial cultures if a combined culture comprising five strains was used. Three strains of the combined culture formed H2O2 and possessed a low catalase activity whereas the remaining two did not produce H2O2 and decomposed hydrogen peroxide at a high rate; this suggests that the catalase mechanism is involved in the elimination of N2O.