Method for producing L-ornithine by whole cell transformation of recombinant Corynebacterium crenatum

Abstract

Arginase from Bacillus cereus is successfully expressed in C. crenatum SDNN403 through shuttle plasmid pXMJ19 between Escherichia coli and Corynebacterium crenatum. Results of enzymatic determination show that an original bacterium has no activity of the arginase; enzyme activity of the arginase of a recombinant engineering bacterium is up to 24.3 U / mg. By using a whole-cell body of the recombinant engineering bacterium as a biocatalyst and the L-ornithine as a substrate, on the basis of enzymatic properties of the arginase, an optimal reaction temperature being 40 DEG C and pH being 9.0 are determined; 200ml of LBG cultivated recombinant bacterium is resuspended in 200ml of substrate buffer solution; the L-ornithine is produced by means of transformation under optimal transformation conditions; after 8h, 149.2g / L L-ornithine is acquired; molar conversion rate of substrate L-ornithine is up to 99.5%. The L-ornithine produced by the method has the advantages of high efficiency, high specificity, low energy consumption and the like.

Description

technical field

[0001] The invention relates to the cloning and expression of the arginase gene to obtain a recombinant engineering bacterium, and simultaneously applies the engineering bacterium to the production of L-ornithine, which belongs to the field of bioengineering and biotechnology. technical background

[0002] L-arginase (E.C.3.5.3.1) is a key enzyme in the urea cycle, which catalyzes the formation of L-ornithine and urea from L-arginine. Arginase is widely found in various animals, plants and In microorganisms, arginases from microorganisms such as Bacillus brevis, Bacillus subtilis and Bacillusthuringiensis have been well studied.

[0003] Ornithine is a basic amino acid, easily soluble in water and ethanol, slightly soluble in organic solvents such as ether. Ornithine accepts two molecules of NH 4 + and a molecule of CO 2 One molecule of L-arginine is formed. L-arginine can also be hydrolyzed into ornithine and urea under the action of arginase.

[0004] ...

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