A method for efficiently producing l-glutamic acid oxidase
A glutamate oxidase, high-efficiency expression technology, applied in the fields of fermentation engineering and enzyme engineering, can solve the problems of α-KG difficulty, environmental pollution, source of raw materials, etc., and achieve the effect of high-efficiency expression
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Embodiment 1
[0029] Example 1 Optimization of lactose induction conditions
[0030] With the recombinant strain FMME089 (PanqingNiu, Enzymatic production of α-ketoglutaric acid from L-glutamic acid via L-glutamateoxidase, Journal of Biotechnology, 2014, 56-62) constructed in our laboratory as the starting strain, the lactose induction conditions were optimized.
[0031] 1) Inoculate the recombinant strain in LB medium, OD 600 When it was between 0.5 and 0.6, 1, 3, 5, 7g / L lactose was added to induce 4h at 37℃, and the expression of LGOX was compared. It was found that the lactose induction effect of 5g / L was the best, and the enzyme activity reached 4.53U / mL ( figure 1 A).
[0032] 2) On the basis of the optimal lactose induction concentration, the expression of LGOX at 3, 4, 5, and 6 h after induction was determined. The results showed that the 5h induction had the best effect, and the enzyme activity reached 4.73U / mL( figure 1 B).
Embodiment 2
[0033] Example 2 Batch fermentation
[0034] The recombinant bacteria were first inoculated on the LB seed medium for 10-12 hours, and then transferred to a 5L fermentor containing 2LLB medium with a 4% inoculum amount. The initial fermentation conditions are: rotating speed 300rpm, temperature 37℃, and aeration volume 1vvm. When OD600=0.5-0.7, the final concentration of 5g / L lactose was used for induction, and the cell concentration and enzyme activity expression at different time points were measured. The results showed that the enzyme activity reached the maximum value of 9.43U / mL 4h after induction.
Embodiment 3
[0035] Example 3 Fed-batch fermentation based on DO-stat
[0036] The start conditions of the fermentor are the same as batch fermentation. Before feeding, control DO above 30%, start feeding when DO suddenly rises, and control DO related feeding. When DO is higher than 30%, supplement for a while. material. The composition of the feed solution is 500g / L of glycerol, and 5g / L of lactose is used for induction when the bacterial concentration does not increase. Fermentation for 16h, cell concentration OD=47.7, enzyme activity 35.55U / mL( image 3 ).
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