Fructokinase-disabled cyanobacteria and application thereof in secretion and production of fructose

Abstract

The invention relates to application of a cyanobacteria fructokinase inactivating agent in preparation of cyanobacteria with fructose secretion capability and high fructose yield, and further relates to a reagent for knocking out a fructokinase gene corresponding to fructokinase in the cyanobacteria or a fructokinase function antagonist. The invention also relates to the fructokinase-disabled cyanobacteria and application of the fructokinase-disabled cyanobacteria in fructose production. According to the invention, fructokinase in a carbon circulation path of cyanobacteria is knocked out, a mutant strain accidentally obtains the capacity of mass production of fructose and secretion of fructose out of cells, the fructose yield is increased by hundreds of times, and the possibility is provided for subsequent industrial production of fructose by using cyanobacteria; and a foundation is provided for further metabolic engineering modification by taking cyanobacteria as a chassis algal strain.

Description

technical field [0001] The present invention relates to the field of synthetic biology of cyanobacteria, and more particularly, to cyanobacteria with fructokinase incapacity and their use in the secretion and production of fructose. Background technique [0002] Fructose is widely used in food, medicine and chemical industries, especially for the prevention of diabetes, obesity, dental caries and other diseases. At present, fructose products on the market have two forms: fructose syrup and crystalline fructose. The production of fructose syrup uses starch as the main raw material. Through the chemical catalytic synthesis route, the starch is firstly hydrolyzed into glucose by using α-amylase and glucoamylase, and then glucose isomerase is used to convert the glucose into a product containing 42% fructose and 58% fructose. % glucose in fructose syrup. Crystalline fructose (fructose with a purity greater than 97%) is a fine powder crystal. Its production is also based on fru...

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Problems solved by technology

However, no potential cyanobacteria with high fructose content have been found in the current research, nor have they been found to have the ability to secrete fructose

Niederholtmeyer et al. transferred the hexose transporter G 1 f gene into Synechococcus sp. PCC7942 to form a fructose secretion pathway, enabling the bacteria to secrete fructose, but even under optimal conditions, it produced the highest extracellular fructose content Only 28.8mg / L, and fructose level declines along with the increase of cell density, does not reach the requirement of suitability for industrialized production (Niederholtmeyer, H., Wolfstadter, B.T., Savage, D.F., Silver, P.A., and Way, J.C., Engineering cyanobacteria to synthesize and exporthydrophilic products.Appl.Environ.Microbiol.,2010.76(11):p.3462-3466)

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