Fermentation for Amino Acids

The market demand for amino acids has been increasing over the last 100 years. As bulk biochemicals, amino acids are used in the production of a wide range of products such flavor enhancers in nutritious foods. Amino acids are involved in regulating key metabolic pathways and processes, such as regulating protein metabolism and controlling the growth and immunity of organisms, which are essential for their growth and maintenance. Clinical studies have shown that amino acid deficiencies can lead to a series of serious diseases. As a result, the interest in producing amino acids in a more cost-effective and sustainable manner has increased significantly. Amino acids can be produced by different processes, such as extraction from protein hydrolysates, chemical synthesis or fermentation routes with the application of microorganisms. Thanks to the rapid development of genetic engineering technologies, fermentation production is becoming one of the most promising approach for the commercial production of amino acids. Under aerobic or anaerobic conditions, several microorganisms are used to convert sugars in a substrate into a broad range of amino acids. Amino acids are most commonly produced industrially by Corynebacterium glutamicum and Escherichia coli.

Fig 1. Amino acids production focusing on fermentation technologies. (D'Este, M.; et al. 2018)

Advantages of Fermentation for Amino Acids Production

Due to economic and environmental advantages, fermentation is currently the most used amino acid production technology at industrial scale. The fermentation process has several advantages over other methods:

It can avoid further purification steps
It can be operated under mild conditions, preventing product degradation
Compared to the extraction processes, the maintenance costs are significantly lower
Fermentation technologies can maximize the yield, specificity and production of target amino acid compounds

Fig 2. Biosynthesis of glutamic acid from glucose. (Sanchez, S.; et al. 2017)

The Fermentation Process

The Selection of Amino Acid Producing Bacteria

The most commonly used bacteria for amino acid production by fermentation are C. glutamicum and E. coli. Both are capable of producing a wide range of amino acids and several metabolic engineering changes have been applied to improve their performance as amino acid producing organisms. Modified C. glutamicum has been used to produce lysine or glutamic acid with high yields, while E. coli has been modified to produce various aromatic amino acids such as L-tryptophan, L-phenylalanine and L-tyrosine.

Fermentation Process Design in Amino Acid Production

Process monitoring

During the fermentation, continuous monitoring of key parameters and process variables such as inoculum mass, pH, feed rate, aeration intensity, and process temperature is required. The inoculum preparation is a critical step in the biological process, as it significantly affects productivity and yield. Therefore, to ensure the optimal inoculation, the stability and yield of the inoculum should be thoroughly tested prior to transfer. To avoid contamination, sterility must be maintained throughout the process. Continuous sterilization systems have been integrated into the fermentor configuration to ensure asepsis during all the stages of the process.

Fed-batch production

In the fed-batch production process, cells and products are left in the reactor in order to obtain a higher yield or productivity. The nutrients required to carry out the fermentation, such as ammonium sulfate or pure ammonia, biotin, pure ammonia, and other vitamins, are provided at the beginning along with the inoculum.

Continuous production

The continuous production mode of operation is applied in the fermentation technology since it can provide higher productivity and process output than fed-batch technology. To improve the performance of the continuous configuration, a cascade bioprocess can be applied. Growth of microorganisms stages can be carried out in a separate reactor rather than in the production process itself, thus allowing the optimization of the conditions of both stages.

Downstream Separation and Purification

Effective downstream and purification processes are essential to reduce the costs related to the amino acid production. The separation of amino acids from fermentation broth is usually accomplished by centrifugation or filtration, followed by purification using chromatographic techniques of choice depending on product characteristics such as solubility, purity, etc.

Fermentation Process Modelling and Analysis Technology

Scale down method

Scale down devices are gaining increasing attention as a tool to mimic the conditions of large-scale bioreactors. In order to have an appropriate predictive model for the performance of large-scale reactors, the scaled down design has to be simulated the reaction conditions of industrial processes

Computational Fluid Dynamics (CFD)

Process modeling can support the design and the optimization of fermentation processes. CFD, considering the process operating parameters, process stoichiometry, and the environmental aspects, enables to estimate the process efficiency, the product titer, selectivity, and optimum yield.

Our Services

BOC Sciences provides fermentation CDMO service for amino acids. We use the fermentation method to produce amino acids. We are able to provide large scale fermentation capacity in excess of 2,000,000 liters and offer our customers fast turnaround times and a seamless manufacturing process.

Workflow of Our Service

Workflow of Our Service

References

D'Este, M.; et al. Amino acids production focusing on fermentation technologies - A review. Biotechnology Advances.2018. 36(1): 14-25.
Sanchez, S.; et al. Our microbes not only produce antibiotics, they also overproduce amino acids. Journal of Antibiotics. 2017. 71: 26-36.