How to optimize the production of acetic acid by biological fermentation?

How to use biological fermentation to optimize acetic acid production?

With the increasing global demand for green chemicals, acetic acid, as an important organic acid, has been widely used in chemical, food, pharmaceutical and other fields. Although the traditional chemical synthesis method has high production efficiency, it has problems such as high energy consumption and pollution. Therefore, the production of acetic acid by biological fermentation has gradually become a research hotspot. In this paper, how to optimize the production of acetic acid by biological fermentation will be analyzed in detail from the aspects of strain optimization, fermentation condition control, product separation and purification.

1. Strain breeding and optimization

The core of acetic acid production by biological fermentation is the use of microbial metabolic capacity. At present, the main strains commonly used include Acetobacter (Acetobacterium sp.) and Escherichia coli (Escherichia coli). These species produce acetic acid by fermenting substrates such as glucose, ethanol, etc. In order to improve production efficiency, the strain needs to be optimized first.

1.1 strain breeding Strain breeding is a key step to optimize acetic acid production. By mutagenizing wild strains (such as ultraviolet mutagenesis, chemical mutagenesis, etc.), high-yield strains can be selected. Genetic engineering technology is also widely used in strain improvement, such as knocking out unfavorable genes in metabolic pathways or overexpressing key enzymes to increase acetic acid production.

1.2 genetic engineering optimization The use of genetic engineering technology to modify the strain can significantly improve the production efficiency of acetic acid. For example, by knocking out genes that compete with acetic acid metabolism, metabolic shunting is reduced, allowing more metabolites to flow to acetic acid. Over-expression of enzymes related to acetic acid synthesis, such as alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), can further improve the production of acetic acid.

2. Fermentation conditions optimization

The fermentation conditions directly affect the yield and product quality of acetic acid. By optimizing the fermentation conditions, the metabolic activity of the strain can be maximized and the formation of metabolic by-products can be reduced.

2.1 fermentation temperature control Temperature is an important parameter in the fermentation process. Different strains have different sensitivity to temperature, so it is necessary to set the appropriate fermentation temperature according to the characteristics of the strain. In general, the optimum growth temperature for Acetobacter is 30-35°C, while the optimum growth temperature for Escherichia coli is about 37°C. By precisely controlling the fermentation temperature, the high-yield metabolism of the strain can be ensured.

2.2 pH regulation The control of pH value is very important for the fermentation process of acetic acid. The formation of acetic acid is usually accompanied by a decrease in pH. Therefore, it is necessary to monitor the pH value in real time during the fermentation process, and to maintain a suitable pH environment by adding a buffer (such as a carbonate buffer) to prevent the strain from being inactivated due to low pH.

2.3 oxygen supply The fermentation process of acetic acid usually requires oxygen. Aerobic bacteria (such as Acetobacter) need to be metabolized under aerobic conditions, while facultative anaerobes (such as Escherichia coli) are more efficient under aerobic conditions. Therefore, by reasonably designing the stirring and aeration system of the fermentation tank to ensure the sufficient supply of oxygen, the production of acetic acid can be significantly improved.

3. Product separation and purification

After the fermentation, the product needs to be separated and purified to obtain high purity acetic acid. Traditional separation methods include distillation, ion exchange and membrane separation, but these methods tend to be more energy-consuming and expensive.

3.1 membrane separation technology In recent years, the application of membrane separation technology in acetic acid separation has gradually increased. By selectively permeable membranes, acetic acid can be effectively separated from other components. Compared with traditional separation methods, membrane separation technology has the advantages of low energy consumption and high efficiency.

3.2 Adsorption and Desorption Technology Adsorption-desorption technology is also an effective separation method. Using materials with high adsorption capacity (such as activated carbon, resin, etc.) to adsorb acetic acid, and then desorb it by eluent, the efficient separation of acetic acid can be achieved.

4. Resource comprehensive utilization

The production of acetic acid by biological fermentation not only needs to pay attention to the production process itself, but also needs to consider the comprehensive utilization of resources and environmental protection. For example, the selection of fermentation substrates, the treatment of by-products, etc. are issues that need to be focused on.

Selection of 4.1 fermentation substrates The choice of fermentation substrate directly affects the production cost. The use of cheap renewable resources (such as straw, starch wastewater, etc.) as fermentation substrates can not only reduce production costs, but also reduce the burden on the environment.

Treatment of 4.2 by-products A large amount of by-products such as residue and waste are produced during the fermentation process. By resource utilization of these by-products (such as feed, fertilizer, etc.), waste recycling can be realized and environmental pollution can be reduced.

5. Future development direction

Although significant progress has been made in the production of acetic acid by biological fermentation, there are still some challenges and shortcomings. For example, how to further improve the metabolic efficiency of strains, how to reduce production costs, how to achieve large-scale industrial production and so on. Therefore, future research needs to start from the following aspects:

5.1 microbial synthetic biology By means of synthetic biology, more efficient acetic acid production strains are constructed, such as using anabolic pathways or modular metabolic engineering to improve acetic acid production.

optimization of 5.2 fermentation process Using process analysis technology (PAT) and intelligent control system, real-time monitoring and regulation of fermentation process parameters (such as temperature, pH, oxygen, etc.) to achieve the optimization of fermentation process.

5.3 Green Separation Technology Develop new green separation technologies, such as supercritical fluid extraction, electrodialysis, etc., to reduce the energy consumption and cost of the separation process.

Conclusion

Optimizing the production of acetic acid by biological fermentation can not only improve the production efficiency, but also reduce the production cost and environmental pollution. From strain optimization, fermentation condition control, product separation and purification to the comprehensive utilization of resources, every link needs to be studied and optimized. With the continuous progress of biotechnology, it is believed that biological fermentation will play a more important role in the production of acetic acid and open up a new way for the production of green chemicals.