Genetic Engineering Bacteria Deleting 21 Coding Exopolysaccharide Synthesis Genes and Its Application

Abstract

The invention discloses a genetically engineered bacterium with deficiency of 21 encoded exopolysaccharide synthetic genes and application thereof, and belongs to the field of gene engineering and fermentation engineering. A mutant bacterium WJW09 is obtained by knocking out 21 genes in charge of exopolysaccharide synthesis and transfer on an escherichia coli W3110 genome through a CRISPR / Cas9 knockout system, with the WJW09 strain as a host bacterium, a PHB synthesis gene cluster phaCAB is heterologously expressed through pBHR68, PHB synthesized through WJW09 / pBHR68 can reach 57.2% of the drycell weight, while PHB synthesized through W3110 / pBHR68 only accounts for 1.5% of the dry cell weight. The PHB volumetric production of the recombinant bacterium WJW09 / pBHR68 is 38 times that of thecontrast bacterium W3110 / pBHR68 (1.5%).

Description

technical field

[0001] The invention relates to a genetically engineered bacterium lacking 21 coding exopolysaccharide synthesis genes and its application, belonging to the fields of genetic engineering and fermentation engineering. Background technique

[0002] Extracellular polysaccharides (EPSs) refer to polysaccharide-containing structures secreted by microorganisms into the surrounding environment, and are polysaccharide components outside the cell membrane of Gram-negative bacteria. Genes related to exopolysaccharide synthesis exist in the genome in the form of gene clusters, encoding glycosyltransferases, polymerases and branching enzymes, and are responsible for adding modification components. In Escherichia coli, exopolysaccharides are mostly synthesized in the form of clarified acid, which is attached to the outer layer of the outer cell membrane and consists of multiple sugar units, each sugar unit contains 6 sugar molecules, and the synthesis of these sugar molec...

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