Auxotrophic Mutant Strains

Many kinds of amino acids are accumulated by auxotrophic strains that mutated to require a growth factor. l-Lysine is produced by a homoserine auxotrophic mutant of glutamic acid-producing bacteria; B. lactofermentum and Corynebacterium glutamicum and typical examples. In glutamic acid bacteria, l-lysine is formed by way of the branched pathway shown in Figure 3. The aspartate kinase, which is the first key enzyme of lysine biosynthesis, is inhibited by the combination of l-threonine and l-lysine, and l-lysine is among the amino acids not overproduced. In the homoserine auxotroph, if the supply of l-threonine is limited, l-lysine formed by de novo synthesis does not inhibit the first enzyme without the aid of l-threonine. In this mutant, the metabolic flux is genetically blocked to flow in the direction of threonine and methionine biosynthesis. This is one of the main reasons for the overproduction of l-lysine in mutant strains (38).

Sleeping Sanctuary

Sleeping Sanctuary

Salvation For The Sleep Deprived The Ultimate Guide To Sleeping, Napping, Resting And  Restoring Your Energy. Of the many things that we do just instinctively and do not give much  of a thought to, sleep is probably the most prominent one. Most of us sleep only because we have to. We sleep because we cannot stay awake all 24 hours in the day.

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