Amino acid fermentation — Which microorganisms have been used industrially to produce L-glutamic acid at scale?
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AMicrococcus glutamicus
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BBrevibacterium aminogenes
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CArthrobacter globiformis
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Dall of these
Answer
Correct Answer: all of these
Explanation
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:
Map each listed genus to documented glutamate production.Note that the industry commonly moved toward optimized Corynebacterium lines but historically used others as well.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