Optimization Of Gene Recombinant Escherichia Coli For Threonine Fermentation

Just as fodder, threonine and lysine, methionine, tryptophan were called togetherrestrictive amino acids, and the threonine is the second one. With the popularization andextensive addition, threonine gradually became, key restrictive amino acids. At present fromthe international market to see, l-threonine is one of the fastest growing demand for amino acids,but our threonine production from the production enterprise quantity to produce acid fermentedstrains rate to threonine extraction, and international advanced countries have the very bigdisparity. This paper is a plant genetic restructuring of escherichia coli strains for starting, andcarry on the seed cultivation condition and fermentation cultivation condition optimizing, makeits decompressing bottle fermentation of the acid yield rate from30.3g/L increase to41.2g/L,and10L the acid yield rate fermentation tank from the original70g/L increase to81.3g/L. Themain work includes the following aspects:Seed development condition optimizing, is to get good seeds, shortens fermentation period,and enhance the utilization ratio of the equipment necessary steps. This paper according to thepractical characteristics of selected strains, in view of the dissolved oxygen, carbon source andpH control, from gauze layer, triangle of choice, the bottle glucose addition, buffer systemconstruction of GSH use a try, and eventually in the original formula, and on the basis of addedbuffer system, makes the kind of age for two hours in advance, shorten the fermentation period.The original formula, nitrogen source used only ammonium sulfate this inorganic nitrogensource, this paper, by adding more corn syrup as organic nitrogen source, and pass to cane sugar,ammonium sulfate and corn syrup of orthogonal experiment after a wave of threonine bottleproduction up by40%.Genetic engineering strains of the bacteria and the normal or mutation income comparedwith high yield strains, more easily degraded, the subject of this plant genetic restructuring ofthe selection of e. coli, he appeared slow growth in the same conditions of acid in phenomenon,then, need the rejuvenation of the strains. After a flat crossed screening, finally separated from15strains of e. coli, screening, the highest yield acid plant, compared with the original strains,acid yield rate is increased.Our country threonine most studies stay in the experimental stage, this paper get wave in bed after optimization medium formula, the10L fermentation conditions of fermentation tankoptimization and fill material control experiment, thus fulfilling the Sue of amino acid forexpanding the production.