An acid-fast, slow-growing scotochromogenic mycobacterium was isolated from a medium specific for hydrogen-utilizing chemolithotrophs. The organism grew well in pure culture in simple mineral salts media under an atmosphere of hydrogen, oxygen, and carbon dioxide. No growth occurred in the absence of the gas mixture unless organic substrates were added. Four tested strains of the tap-water scotochromogen, Mycobacterium gordonae, were also able to grow autotrophically, whereas none of eight tested strains of M. scrofulaceum grew using hydrogen. Twenty-one other mycobacterial strains were negative for autotrophic growth; a strain of M. xenopi grew very slowly. The isolated scotochromogen conformed to the properties of M. scrofulaceum except for its ability to grow at 19 C and its autotrophic ability. This organism exhibited two major colony types. During autotrophic cultivation, a flat, rough colony form was dominant; heterotrophic cultivation caused a population shift to a smooth, domed variety. The two colony forms exhibited qualitatively similar biochemical properties, and the unusual rough-to-smooth transition seemed to correlate with the quantitatively enhanced heterotrophic growth capacities of the smooth strain. Rough-to-smooth variation was reversible, and predominantly smooth inocula gave rise to predominantly rough populations under conditions of chemoautotrophy. The ability to grow autotrophically may be a useful characteristic for distinguishing the saprophytic scotochromogens from the more pathogenic strains.
DeCiccoB. T.,
StukusP.E.1968; Autotrophic and heterotrophic metabolism of Hydro- genomonas. I. Growth yields and patterns under dual substrate conditions. J. Bacteriol 95:1469–1475
HalpernB.,
KirchheimerW.F.1954; Studies on the growth of mycobacteria. II. The effect of oxygenation and aeration on growth patterns of mycobacteria. Amer. Rev. Tuberc 70:665–671
KubicaG. P.1973; Differential identification of mycobacteria. VII. Key features for identification of clinically significant mycobacteria. Amer. Rev. Resp. Dis 107:9–21
KubicaG. P.,
DyeW.E.1967; Laboratory methods for clinical and public healthmycobac- teriology. Public Health Service Publication no. 1547. U.S.Government Printing Office; Washington,D.C.:
ReznikovM.,
LeggoJ.H.1972; Modification of Schaefer’s procedure for serotyping of organisms of the Mycobacterium avium-M.intra- cellulare-M. scrofulaceum complex. Appl. Microbiol 23:819–823
SchaeferW. B.1968; Incidence of the serotypes of Mycobacterium avium and atypical mycobacteria in human and animal diseases. Amer. Rev. Resp. Dis 97:18–23
WayneL. G.,
DoubekJ.R.,
DiazG.A.1967; Classification and identification of mycobacteria. IV. Some important scotochromogens. Amer. Rev. Resp. Dis 96:88–95