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Updated: May 28, 2026

Identification of Mycobacterium Species by DNA Microarray Chip Method
Published on: June 24, 2025
Acidochromogenicity is a common characteristic in nontuberculous mycobacteria
Beatrice Saviola1, Jeffrey Felton
1Basic Medical Sciences, College of Osteopathic Medicine, Western University of Health Sciences, 309 E, Second St,, Pomona, CA 91766, USA. bsaviola@westernu.edu.
Background:
An acidic environment is something likely encountered by mycobacteria in the environment or in a human host. Previously mycobacterial species had been known to produce carotenoid pigments in response to light or constitutively.
Results:
We have tested the ability of various mycobacteria to grow on solid agar plates of differing acidity, and have shown that many species of mycobacteria previously thought to not produce pigment are pigmented when exposed to acidic stress. The Mycobacterium smegmatis promoter region upstream of the genes homologous to those of other mycobacterial species known to code for proteins involved in carotenoid biosynthesis was found to be upregulated under acidic stress.
Conclusions:
Mycobacterial species can produce pigment in response to conditions not previously known to induce chromogenicity in mycobacteria. In addition many mycobacterial species previously thought to not produce pigment are actually chromogenic under acidic conditions.
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