History of amino acid biotechnology: Which amino acid was the first to be commercialized at large scale via microbial processes, catalyzing the growth of the amino acid industry?

Introduction / Context:
The amino acid industry began with pioneering fermentations that proved microbes could produce commodity biochemicals economically. Recognizing the first commercial success helps frame the evolution of modern bioprocessing.

Given Data / Assumptions:

• We are identifying the earliest large-scale commercial amino acid from fermentation.
• Historical context: post–World War II developments in Japan and worldwide.
• Industrial significance: food flavoring and feed markets.

Concept / Approach:
L-glutamic acid was the first amino acid produced at scale by fermentation, originally for monosodium glutamate (MSG) as a flavor enhancer. Early processes used Micrococcus/Arthrobacter, later replaced by Corynebacterium glutamicum due to superior yields and stability. This milestone validated microbial amino acid production and paved the way for L-lysine, L-threonine, and others.

Step-by-Step Solution:
Recall the historical development of MSG production via fermentation.Match the product to L-glutamic acid, the precursor to MSG.Select “L-glutamic acid.”

Verification / Alternative check:
Company histories and classic bioprocess texts cite the transition from extraction to fermentation for glutamate as the industry’s starting point.

Why Other Options Are Wrong:
L-lysine commercialization followed later; L-methionine is largely produced chemically; L-cystine and L-tryptophan were not the first large-scale fermentation successes.

Common Pitfalls:
Confusing earliest discovery with earliest scalable industrialization; glutamate led the way due to strong market demand (MSG).

Final Answer:
L-glutamic acid.