Amino acid fermentation — Which microorganisms have been used industrially to produce L-glutamic acid at scale?

Introduction / Context:
L-glutamic acid production launched modern amino acid biotechnology. Several Gram-positive, high-GC “coryneform” bacteria and related genera have been exploited because they secrete glutamate under specific physiological conditions (e.g., biotin limitation, surfactant addition).

Given Data / Assumptions:

• Micrococcus (Corynebacterium) glutamicus is the textbook organism.
• Brevibacterium and Arthrobacter species can also produce glutamate with appropriate triggers.
• Question asks for all organisms used, not the single most common one.

Concept / Approach:
Industrial portfolios include multiple genera selected for robustness, substrate range, and secretion behavior. Therefore, the answer is inclusive of all listed microorganisms.

Step-by-Step Solution:

Verification / Alternative check:
Process reviews and patents cite Brevibacterium aminogenes and Arthrobacter globiformis among capable producers, alongside C. glutamicum.

Why Other Options Are Wrong:
Choosing a single organism ignores the breadth of industrial practice and literature.

Common Pitfalls:
Equating “most common” with “only.”

Final Answer:
all of these