Nitrite production by heterotrophic bacteria.

Heterotrophic bacteria were studied which produced nitrite in the presence of ammonia and in the absence of nitrate. A soil extract medium was prepared which allowed good growth as well as nitrite production in the absence of nitrate. Quantitative data are recorded showing that ammonia decreases as nitrite accumulates when four different cultures are grown in the soil medium. Resting cell studies add further evidence that some heterotrophic bacteria can convert ammonia to nitrite. A defined medium was prepared containing glucose or sodium acetate as the carbon source and NH,CI as the nitrogen source. This medium supported growth and nitrite production ; however, optimum conditions for growth were not established. Neither growth nor nitrite accumulation was as great in defined media as in soil-extract media. Results from defined media and from resting-cell studies rule out the possibility of any nitrate contamination.