Rhodobacter sphaeroides engineering strain for producing beta-carotene and construction method thereof

Abstract

The invention discloses a rhodobacter sphaeroides engineering strain for producing beta-carotene and a construction method thereof. The method includes first optimizing a codon of a lycopene cyclase gene crtYPa derived from pantoea agglomerans to obtain an opt crtYPa gene, then replacing an endogenous phytoene three-step dehydrogenase gene crtI3 of rhodobacter sphaeroides with the opt crtYPa genecontaining a promoter prrnB and a phytoene four-step dehydrogenase gene crtIPa gene derived from the pantoea agglomerans in a traceless mode, then knocking out an endogenous neurosporene hydroxylase gene crtC of the rhodobacter sphaeroides and a 6-phosphoglucose dehydrogenase gene zwf and finally knocking out an endogenous 1-deoxyxylulose-5-phosphate synthase gene dxs of the rhodobacter sphaeroides with integration expression at zwf position to obtain the rhodobacter sphaeroides engineering strain for producing the beta-carotene. The strain is cultured by fermentation, and the content of the beta-carotene can reach 30mg / g DCW.

Description

technical field [0001] The invention belongs to the technical field of metabolic engineering, and in particular relates to a method for constructing a β-carotene-producing strain by transforming Rhodobacter sphaeroides with metabolic engineering. Background technique [0002] β-carotene is widely found in carrots, wolfberry and other green vegetables and yellow and orange fruits. Due to its unsaturated structure, it has strong antioxidant activity and the ability to scavenge free radicals, which can effectively improve the immune function of the body , has been widely used in functional food, medicine and health care and cosmetics and other fields, and the international market demand is increasing day by day. [0003] Natural β-carotene mainly comes from plant extraction and microbial fermentation, but the production cost of plant-derived β-carotene remains high due to the limitation of raw materials, while chemically synthesized β-carotene is mostly all-trans structure, bio...

AI Technical Summary

Problems solved by technology

[0004] At present, the only strain used for industrial production of β-carotene is Blakesleatrispora, but Blakesleatrispora lacks effective molecular manipulation technology, and its bacteria are divided into positive and negative bacteria, with complex metabolic regulation. There are also many problems in its fermentation, such as the fermentation process is complicated, unstable, and the cycle is long.

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