La dénitrification chez Bacillus licheniformis

Abstract

The denitrifying capacity of 15 strains of Bacillus licheniformis was evaluated. In general, N₂ production by the cultures on complex media containing NO₃⁻ is irregular and quite slow and three of the strains never produce gas. Bacillus licheniformis grows rapidly in anaerobiosis on peptone medium containing NO₃⁻ which is reduced to NO₂⁻. None of the strains grow in peptone medium with NO₂⁻ or N₂O as the respiratory substrate, nor do they grow under an atmosphere of 10% NO–90% N₂. Denitrification was studied in cell suspensions using gas chromatography. N₂O production from NO₃⁻ or NO₂⁻ is always weak at best; nitric oxide is reduced to N₂O at an appreciable rate. All the strains synthesize nitrate reductase A in anaerobiosis when NO₃⁻ is present. In cell extracts, nitrite reductase activity is always negligible or nil with tetramethyl-p-phenylenediamine as an electron donor.