Method for producing DHA by Schizochytrium in high-density culture through fermentation

Abstract

The invention discloses a method for producing DHA by Schizochytrium in high-density culture through fermentation, relates to a preparation method of DHA, and provides a method for producing DHA by using a microbial fermentation method, which replaces fish oil to extract omega-3 polyunsaturated fatty acids. The method comprises the following steps of: inoculating strains in a shake flask according to the ratio of strains to a culture medium of 1: (5-10) for culturing until the dry weight of cells in fermentation liquor is 10-12g / L; inoculating the strains in the shake flask in a 1000L seed fermenter according to the inoculum size of 5-10%, culturing until the dry weight of the cells in the fermentation liquor is 20-24g / L; inoculating the strains in the 1000L seed fermenter in a 8000L seed fermenter according to the inoculum size of 5-10%, and culturing for 120-130 hours, wherein the dry weight of the cells in the fermentation liquor is 120-150g / L, and the DHA content is up to 26-30g / L. In the invention, through optimizing the culture medium and optimizing the culture conditions and by adopting a conventional fermentation method, the production rate of the DHA is at least 3 times more than the reported production rate. The production costs of the strains (the Schizochytrium), the culture medium and the culture condition are low, the yield is high, and the method is applicable to the industrial production of the DHA.

Description

technical field [0001] The invention relates to a preparation method of DHA, in particular to a method for producing DHA by a microbial fermentation method. Background technique [0002] Docosahexaenoic acid (DHA) is an Omega-3 polyunsaturated fatty acid, which is difficult for animals to synthesize. It has important physiological regulation functions and medical and health care functions. The traditional source of DHA is mainly extracted from marine fish and their fish oil, but this method has the following disadvantages: [0003] (1) Resources are limited and output is unstable. The composition of fish oil fatty acids from each source, that is, the content of omega-3 polyunsaturated fatty acids, varies with the species of fish, season of fishing, climate and location, and the production of fish oil fluctuates greatly. Now, the global annual output of fish oil is 1 million tons, including 100,000 to 250,000 tons of polyunsaturated fatty acids. If all these fish oils are u...

AI Technical Summary

Problems solved by technology

Now, the global annual output of fish oil is 1 million tons, including 100,000 to 250,000 tons of polyunsaturated fatty acids. If all these fish oils are used to extract omega-3 polyunsaturated fatty acids, the obtained EPA (eicosapentaenoic acid) and DHA is only enough to supply 55 to 104 million people with a daily intake of 5g per person, which is far from meeting market demand

[0004] (2) The purification process is complex and the product yield is low

Theoretically, 100,000-250,000 tons of DHA can be obtained from 1 million tons of fish oil. However, in the actual production process, fish oil is mostly hydrogenated, and omega-3 polyunsaturated fatty acids are hydrogenated and saturated, which reduces its content in fish oil, resulting in It reduces the waste of raw materials and also damages the quality of DHA and EPA. With the in-depth understanding of the physiological, nutritional and pharmacological effects of ω-3 polyunsaturated fatty acids, the medicinal demand for ω-3 polyunsaturated fatty acids such as DHA In view of the difficulty in purification of fish oil, the current production of marine fish oil is far from meeting the market demand, and alternative resources must be found

[0005] (3) It is difficult for fish oil products to be used in the food additive industry

Because fish oil has a heavy and unpleasant fishy smell, it is still difficult to remove the fishy smell even after complex purification processes, which greatly limits the application of these high value-added products in the food industry

If some methods (such as: embedding, etc.) are used to cover up or remove the unique fishy smell of fish oil, the cost of the product will be increased virtually, which is not conducive to the market competition of the product

[0006] (4) Not conducive to the protection of environmental resources

Due to the growing awareness of the physiological role of omega-3 PUFAs, the market demand for omega-3 PUFAs such as DHA is also increasing, which can also lead to some reckless overdoses for commercial gain The emergence of fishing behavior has brought negative impacts on the protection of environmental resources