Breeding Of L-serine Producing Strain And Optimization Of Fermentation Condition

This article inspected the characteristic of L-serine gene engineering strain Brevibacterium flavm C-11A, and preliminary studied its flask-shaking fermentation condition and its producing L-serine ability. Then carries on to it induces mutation or chromosomal change processing, obtains the tryptophan nutrition flaw to obtain high L-serine, and optimizes the condition of its flask-shaking fermentation, increasing the L-serine . The main researchs content and the result are as follows:1.Inspecting that gene engineering strain Brevibacterium flavm C-11A is the non- nutrition flaw, it has the capability of non-resolution serine , anti-chloramphenicol, and anti- streptomycn. Mycelium activates way by MPB to producing L-serine is higer than the mycelium way by the water to producing L-serine . The buffer is0.3 % K₂PO₄ , the yeast paste is the organic nitrogen source , (NH₄)₂SO₄ is bio-Inorganic source,CaCO₃ sterilizes not with media.2.0n the condition of carefully studying the L- serine biosynthesis, mutating the changin gene engineering Brevibacterium flavm C-11A, the result display that only mutation by NGT, the strain is easy to reverse mutation, but combination mutation the way of physics and the chemical, finally obtains a tryptophan nutrition flaw ,which steadily and produce high L-sreine, we named it C34.3.Carries on the flask-shaking optimization to C34, to get good flask-shaking fermentation condition and culture medium formula.The seed culture medium formula for the yeast paste 1 %, the sugar 3 %, K₂PO₄ 0.3 %, the initial pH is 8.0, seeding age is 32-37 take advantageous of producing high L-serine. Fermentation medium formula: (NH₄)₂SO₄ is 3%, the inoculum 10 %, the yeast paste 1.2 %, the C₄H₄O₄2 %, the sugar 4 %, the fermentation condition is: Initial pH is 8.4, the 500ml triangle bottled liquid volume is 20ml.