Colorimetric method to detect ε-poly-l-lysine using glucose oxidase

Area of Science:

• Biochemistry
• Analytical Chemistry

Background:

• ε-poly-l-lysine (εPL) is a biopolymer produced via fermentation.
• Accurate detection of εPL is crucial for optimizing production and screening.
• Existing methods may require complex sample pretreatment.

Purpose of the Study:

• To develop a novel, sensitive colorimetric assay for εPL detection.
• To enable direct quantification of εPL in complex biological matrices like fermentation broth.
• To facilitate the screening of εPL-producing microorganisms and enzymes.

Main Methods:

• Utilized glucose oxidase (GOx) enzyme activity, enhanced by εPL.
• Monitored the color change resulting from ferricyanide reduction to ferrocyanide.
• Determined detection limits for purified εPL and in fermentation broth.
• Investigated the effect of combining with the Berlin blue reaction.

Main Results:

• Achieved a detection limit of 0.5 mg/L for purified εPL.
• Detected εPL directly in fermentation broth at concentrations as low as 20 mg/L.
• Reduced the detection limit in broth to 10 mg/L by incorporating the Berlin blue reaction.
• Demonstrated minimal interference from culture broth components due to high assay sensitivity.

Conclusions:

• The proposed colorimetric assay is simple, sensitive, and effective for εPL detection.
• The method allows for direct analysis of εPL in fermentation broths without pretreatment.
• This assay is a valuable tool for screening εPL synthetic enzymes and microorganisms.