Escherichia coli JLTrp and application thereof to fermentation production of L-tryptophan

Abstract

The invention relates to Escherichia coli JLTrp and application thereof to the fermentation production of L-tryptophan. The Escherichia coli JLTrp has a culture collection number of CGMCC NO. 7.217. The application of the Escherichia coli JLTrp to the fermentation production of the L-tryptophan comprises the following steps: performing inoculation with mature cultures in a fermentation tank, at a temperature of 34-36 DEG C, controlling pH (potential of Hydrogen) in a staged manner by adopting liquid ammonia replenishment, controlling dissolved oxygen in the staged manner, controlling the pressure to be 0.03-0.08MPa and the air volume to be 0.3-2.0VVM, controlling residual sugar to be 0.01-0.5% in a process, and cultivating and preparing L-tryptophan. A bacterial strain of the Escherichia coli JLTrp greatly improves the stability of the cultures, and reduces the generation, which is caused by insufficient conditions, of an organic acid, so that the vitality of the cultures is improved, cultivation conditions are gradually lowered, and energy consumption is greatly reduced. Escherichia coli JLTrp provided by the invention can be used for the fermentation production of L-tryptophan, is relatively greatly improved in both yield and percent conversion, and has obvious progress.

Description

technical field [0001] The invention relates to the technical field of industrial microorganism breeding, in particular to its application in fermentative production of L-tryptophan. Background technique [0002] L-tryptophan is an important nutritional agent, widely used in amino acid infusion, nutritional supplements, food and feed additives, and is an important feed additive after methionine, lysine, and threonine. In recent years, with the continuous development of feed industry and pharmaceutical industry at home and abroad, L-tryptophan has become a product with great demand. In this case, a large number of enterprises at home and abroad are devoted to the research and development of L-tryptophan, and the fermentation level has been continuously improved. However, due to the high requirements of the strains on raw materials, ventilation and process, in the production process, due to the genetic instability of the strains, the acid production is unstable, the level is ...

AI Technical Summary

Problems solved by technology

However, due to the high requirements of the strains on raw materials, ventilation and process, in the production process, due to the genetic instability of the strains, the acid production is unstable, the level is only 2.0-2.5%, and the conversion rate is only 12-15%. %, at the same time, raw materials and energy consumption are relatively large, resulting in high production costs and small profit margins in the face of the market

The strains currently used to produce L-tryptophan in our company are genetically unstable. Antibiotics cause the defect of the non-specific porin OprF in the outer membrane of Escherichia coli, resulting in the synthesis of trimers of non-specific porins that are hydrophilic in the outer membrane. The structure changes, so that the cell membrane has better selective permeability, avoiding the destruction of the intracellular matrix by the organic acid produced by the abnormal conditions during the fermentation process, affecting the vitality of the bacteria, and at the same time, due to the high requirements on the process conditions, the strains When the subculture or fermentation conditions are limited, the strains will mutate, which not only affects the yield but also changes the metabolic pathway, producing metabolites that are not what we expect, resulting in a low sugar-acid conversion rate and increased energy consumption

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