Optimization of the Biocatalysis for D-DIBOA Synthesis Using a Quick and Sensitive New Spectrophotometric...

Area of Science:

• Biotechnology and Biocatalysis
• Analytical Chemistry
• Agricultural Science

Background:

• D-DIBOA (4-hydroxy-(2H)-1,4-benzoxazin-3-(4H)-one) is a valuable allelopathic compound with herbicidal, fungicidal, and insecticidal properties.
• Biocatalysis using engineered *Escherichia coli* has enabled D-DIBOA production, but process optimization is hindered by slow, costly, and solvent-intensive quantification methods like HPLC.
• A need exists for a faster, simpler, and more environmentally friendly method for D-DIBOA quantification to facilitate process development.

Purpose of the Study:

• To establish and validate a rapid, simple, and sensitive spectrophotometric method for quantifying D-DIBOA produced via whole-cell biocatalysis.
• To utilize this new method to optimize D-DIBOA production strategies and improve yield.

Main Methods:

• Development and validation of a spectrophotometric assay for D-DIBOA quantification.
• Implementation of the assay in a microtiter plate format for high-throughput analysis.
• Application of the method to monitor and optimize whole-cell biocatalysis of D-DIBOA in *Escherichia coli*, including hourly monitoring of precursor and product concentrations.

Main Results:

• A rapid (seconds), sensitive spectrophotometric method for D-DIBOA quantification was successfully established and validated, with limits of detection and quantification of 0.0165 and 0.0501 µmol·mL⁻¹, respectively.
• The method requires minimal sample volume (100 µL) and is compatible with standard microtiter plate readers.
• Optimization using the new method led to a 43% increase in D-DIBOA production, from 5.01 mM to 7.17 mM.

Conclusions:

• The developed spectrophotometric method offers a significant improvement over HPLC for D-DIBOA quantification in biocatalysis.
• This simplified and rapid analytical approach will accelerate the optimization of biocatalysts, scale-up processes, and downstream purification of D-DIBOA.
• The enhanced D-DIBOA production demonstrates the effectiveness of the optimized biocatalysis strategy facilitated by the new quantification method.