As a biocatalyst, enzymes are closely connected to life activities. On the one hand, the activity level of the enzyme in the body reflects the biological condition of the organism; on the other hand, if the activity level of the enzyme in the organism is controlled, the activity of the organism can be adjusted accordingly. Therefore, it is of prime importance to understand the biological laws and knowledge of enzymes for the production practice. For example, in industrial and agricultural production, especially in fermentation production, it is possible to increase the yield by controlling the external conditions or modifying genetic factors to carry out metabolic control.
1.Add enzyme inhibitors
Take citric acid production as an example. In the fermentation production of citric acid, a certain amount of isocitric acid is often accompanied by the presence of aconitase in the bacterium, which converts part of the citric acid to isocitric acid. For this reason, if inhibitors such as fluoroacetic acid are added to the fermentation system or the supply of iron ions is restricted in the culture medium, the activity of aconitase is inhibited, and the generation of isocitrate can be reduced but the yield of citric acid can be increased. Based on the same reason, a fluoroacetic acid-sensitive mutant strain was obtained by mutagenesis. As a result, the citric acid yield was also significantly improved.
2.Control key enzymes in metabolic systems
Take lysine production as an example. Lysine can be produced using a variety of strains, of which the more commonly used is Brevibacterium flavum. Lysine and threonine exhibit synergistic feedback inhibition effects on the first enzyme (the aspartokinase) in this metabolic pathway, in this bacterial lysine synthesis regulation mechanism; however, unlike E. coli, lysine has no feedback regulation on the first enzyme of the branched metabolic pathway, dihydropyridine carboxylic acid synthase. According to this feature, it is apparent that as long as the concentration of threonine is controlled and the synergistic feedback inhibition is overcome, lysine can be synthesized in a large amount. Based on this knowledge, mutagenesis obtained mutant strains deficient in homoserine dehydrogenase (it cannot synthesize threonine). When culturing the auxotrophic mutant, if the supply of exogenous threonine and methionine is simultaneously restricted, the lysine production can be increased to 40 g/L or more.
3.Add enzyme preparation
Still taking fermented production as an example, during the fermentation process, if certain enzyme preparations are added to the system to increase the permeability of the cells of the cells, promote the secretion of the products, and overcome the feedback inhibition, the yield should be significantly increased. The facts also show that the desired effect can often be obtained through this route. For example, when glutamic acid is produced from amphobacillus ammonia and 7% of beet molasses is used as a carbon source, if 0.08% of lysozyme is added after 10 hours of fermentation, glutamic acid production can be increased by a factor of 6 after 48 hours; if After 4 hours of fermentation, 10 u/ml of lipase was added, and the yield after 48 hours could be increased by 12 times.
Related Services at Creative Enzymes:
Enzyme Engineering and Modification
Leave a Reply