A rapid throughput assay for screening (R)-2-(4-hydroxyphenoxy)propionic acid producing microbes

Area of Science:

• Biotechnology
• Microbial Chemistry
• Analytical Chemistry

Background:

• (R)-2-(4-hydroxyphenoxy)propionic acid ((R)-HPOPA) is a key intermediate for synthesizing optically pure aryloxyphenoxypropionic acid herbicides.
• Microbial regioselective hydroxylation of (R)-2-phenoxypropionic acid ((R)-POPA) is a preferred industrial method for (R)-HPOPA production.

Purpose of the Study:

• To design and optimize a rapid, high-throughput assay for screening bacterial and fungal strains capable of regioselective hydroxylation of (R)-POPA to (R)-HPOPA.
• To validate the assay's accuracy, repeatability, and comparability with existing analytical methods.

Main Methods:

• Developed a spectrophotometric assay utilizing the reaction of (R)-HPOPA with 4-aminoantipyrine (4-AAP) and potassium hexacyanoferrate to form a detectable orange-red chromophore.
• Quantified the chromophore at 550 nm for spectrophotometric determination.
• Verified assay performance through recovery rate analysis and comparison with High-Performance Liquid Chromatography (HPLC).

Main Results:

• The assay demonstrated high accuracy with average recovery rates between 97.3% and 104.5%.
• No significant differences in (R)-HPOPA detection were observed between the rapid assay and HPLC.
• The optimized assay is simple, rapid, accurate, and highly repeatable, with a screening capacity of approximately 3000-5000 samples per day.

Conclusions:

• The developed rapid throughput assay is a reliable and efficient tool for screening microbial strains that produce (R)-HPOPA.
• This method significantly enhances the efficiency of identifying and isolating high-performing microbial strains for industrial herbicide intermediate production.
• The assay's simplicity and high throughput potential make it valuable for biotechnological applications in herbicide synthesis.