Which bacterium is used to produce the amino acid glutamate for monosodium glutamate fermentation?

Corynebacterium glutamicum is the bacterium widely used to produce glutamic acid, the amino acid used to make monosodium glutamate through industrial fermentation.

The species became important after Japanese researchers at Kyowa Hakko discovered that a Corynebacterium strain accumulated large amounts of glutamate in its culture broth in 1957. This finding helped establish modern amino-acid fermentation as a major biotechnology industry.

Industrial strains are selected and engineered to direct carbon flow toward glutamate while limiting competing metabolic pathways. The broth is processed to recover glutamic acid, which can then be converted into monosodium glutamate, commonly abbreviated MSG. MSG is the sodium salt of glutamic acid, not a bacterium or a naturally occurring microbial toxin.

C. glutamicum is related to medically important coryneform bacteria but is generally treated as a non-pathogenic industrial organism. Its role in fermentation is distinct from the production of yogurt, vinegar, or alcoholic beverages.