(R)-PAC biosynthesis in [BMIM][PF₆]/aqueous biphasic system using Saccharomyces cerevisiae BY4741 cells

Area of Science:

• Biotechnology and Bioprocess Engineering
• Green Chemistry and Sustainable Processes

Background:

• (R)-phenylacetylcarbinol [(R)-PAC] is a key precursor for synthesizing ephedrine and pseudoephedrine.
• Conventional biotransformation using pyruvate decarboxylase faces challenges due to substrate, product, and by-product toxicity.
• Toxicity issues limit the efficiency and yield of (R)-PAC production.

Purpose of the Study:

• To enhance (R)-PAC production using an ionic liquid/aqueous biphasic system.
• To optimize biotransformation variables for maximizing (R)-PAC yield and productivity.
• To investigate the mitigation of toxic compounds and by-products in the biphasic system.

Main Methods:

• Utilized Saccharomyces cerevisiae BY4741 as the source of pyruvate decarboxylase in a fermented broth medium.
• Employed a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), as the non-aqueous phase.
• Applied Box-Behnken design and response surface methodology for optimizing biotransformation parameters.

Main Results:

• The biphasic system, particularly at a phase volume ratio of 0.05, achieved approximately 1.5-fold higher (R)-PAC yield and productivity compared to monophasic systems.
• The concentration of the major by-product, benzyl alcohol, was reduced by 3.5-fold in the biphasic system.
• Demonstrated biocompatibility of [BMIM][PF6] and favorable distribution coefficients for key compounds.

Conclusions:

• The [BMIM][PF6]/aqueous biphasic system offers a novel and effective strategy for intensifying (R)-PAC production.
• This approach successfully addresses toxicity limitations inherent in conventional biotransformation methods.
• The developed system shows significant potential for more efficient and sustainable pharmaceutical precursor synthesis.