Corynebacterium glutamicum

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Corynebacterium glutamicum
Corynebacterium glutamicum

Corynebacterium glutamicum

Systematics
Department : Actinobacteria
Order : Actinomycetales
Subordination : Corynebacterineae
Family : Corynebacteriaceae
Genre : Corynebacterium
Type : Corynebacterium glutamicum
Scientific name
Corynebacterium glutamicum
( Kinoshita et al. 1958) Abe et al. 1967

Corynebacterium glutamicum is a gram-positive , non-pathogenic and fast-growing soil bacterium of great biotechnological importance, the genome of which has now been completely sequenced. It was discovered in 1957 in Japan as a natural producer of glutamic acid . In the meantime, fermentative production processes with C. glutamicum and closely related organisms have been developedfor almost all biogenic amino acids and a number of other substances such as nucleotides and vitamins .

Production of glutamic acid

Corynebacterium glutamicum forms L-glutamic acid as a secondary product of the citric acid cycle through the transamination of 2-oxoglutaric acid . The main sources of carbon are molasses or starch hydrolyzate. Ammonia, on the other hand, mostly serves as a nitrogen source.

Biotechnological importance

The mutants used in biotechnology show some changes compared to the freely occurring bacteria. The following should be mentioned in particular:

Increase in the secretion of glutamic acid

The overproduction of glutamic acid depends on the permeability (solid permeability ) of the cell. The more permeable the cell, the more glutamic acid can be released into the surrounding medium. Cell permeability can be influenced by a deficiency in biotin , oleic acid , glycerine or by the addition of penicillin .

Regulation of some enzymes on the biosynthetic pathway

The activity of the enzyme 2-oxoglutarate dehydrogenase is markedly reduced in C. glutamicum strains used biotechnologically in comparison to L-glutamate dehydrogenase . Also, some enzymes are regulated by the concentration of metabolites , end products, NH 4 + and NADH .

Activation of multiple anaplerotic reactions

The carboxylation of phosphoenolpyruvate (PEP) and the activation of the glyoxylate cycle increase the formation of oxaloacetic acid . This represents the precursor of citric acid and can therefore bind further carbon atoms from glycolysis in the citric acid cycle. The enzyme PEP carboxylase , which catalyzes the carboxylation of PEP, also needs biotin , which can then no longer be used to build up the cell wall.

Furthermore, C. glutamicum is used as a non-pathogenic model organism for the related human pathogens Corynebacterium diphtheriae , Mycobacterium tuberculosis and Mycobacterium leprae .

Web links

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