Pigment variations in photochromogenic mycobacteria with special reference to M. vaccae

Abstract

Each of four photochromogenic mycobacterial species has a distinguishing feature related to pigmentation.M. kansasii forms extracellular crystals of beta carotene; the other species form no extracellular crystals or(M. marinum) only few. Strain ≠ 1312, an unclassified rapid grower, is distinctive in failing to show induction in yellow light.

M. vaccae is distinctive in being scotochromogenic as well as photochromogenic at temperatures 24°–41° and in exhibiting higher sensitivity to oxygen lack, light exposure, and nutrient medium constitution.

The rarely occuring scotochromogenicM. kansasii are peculiar in a very pronounced crystalline pigment production.

The experiments here reported confirm the belief that variations in pigment, as of other mycobacterial properties do not fluctuate wildly, but are consistent, and useful for species characterization if the requirements of pure cultures and defined conditions are met.