Medical Dictionary

photochromogen

noun pho·to·chro·mo·gen \ˌfōt-ō-ˈkrō-mə-jən\

Medical Definition of PHOTOCHROMOGEN

:  a microorganism especially of the genus Mycobacterium (as M. kansasii) that has little or no pigment when grown in the dark but becomes highly pigmented when grown in light

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