Utilization of nitrate by pathogenic and saprophytic mycobacteria

Abstract

Hedgecock, L. W. (Veterans Administration Hospital, Kansas City, Mo.) and R. L. Costello. Utilization of nitrate by pathogenic and saprophytic mycobacteria. J. Bacteriol. 84:195-205. 1962-The ability of mycobacteria to utilize nitrate as a sole source of nitrogen was examined. Nitrate-nitrogen was readily utilized by Mycobacterium butyricum, M. smegmatis, and M. tuberculosis H37Ra. Nitrate and nitrite were both utilized as sole sources of nitrogen by M. tuberculosis H37Rv. The saprophytes and drug-resistant strains of tubercle bacilli failed to reduce nitrate after having been cultured repeatedly and stored in Kirchner medium. It was necessary to add molybdenum to Kirchner medium for continued nitrate reduction by the saprophytic mycobacteria, but not for M. tuberculosis. Nitrate reductase of M. tuberculosis was inhibited by tungstate; the inhibition was reversed by molybdate at a concentration of 1:10,000. Optimal conditions for the reduction of nitrate by washed whole cells and by a particulate sonictreated extract of M. tuberculosis were studied. Reduced diphosphopyridine nucleotide was required for reduction of nitrate by the cell extract. Nitrate reduction was inhibited by isoniazid but not by p-aminosalicylic acid or streptomycin.