Development of a multienzyme reactor for dopamine synthesis: II. Reactor engineering and simulation

Area of Science:

• Biochemical Engineering
• Enzyme Technology
• Biocatalysis

Background:

• Multienzyme reactions are crucial for synthesizing complex molecules.
• Optimizing reaction engineering for enzymatic processes is key to efficient biocatalysis.
• Dopamine synthesis involves sequential enzymatic steps.

Purpose of the Study:

• To investigate reaction engineering aspects of multienzyme systems for dopamine production.
• To coimmobilize microbial cells expressing tyrosine phenol lyase (TPL) and tyrosine decarboxylase (TDC).
• To evaluate the efficiency of sequential versus simultaneous reactions for dopamine synthesis.

Main Methods:

• Coimmobilization of Erwinia herbicola (TPL) and Streptococcus faecalis (TDC) in gelatin beads.
• Characterization of transport properties within the immobilized cell matrix.
• Packed-bed reactor studies for dopamine production.
• Computer simulations to compare sequential and simultaneous reaction strategies.

Main Results:

• Gelatin matrix showed minimal diffusion resistance for substrates and products.
• Dopamine exhibited partitioning into the gelatin matrix (K=2).
• Successful dopamine production was achieved in a packed-bed reactor, albeit with low conversion.
• Computer simulations indicated sequential reactions require smaller reactors for equivalent dopamine yield.

Conclusions:

• Coimmobilized microbial cells in gelatin beads are viable for multienzyme reactions.
• Sequential enzymatic reactions are more reactor-efficient for dopamine production compared to simultaneous reactions.
• Further optimization is needed to improve conversion rates in the packed-bed reactor system.