A genetically encoded L-rhamnose biosensor for monitoring marine polysaccharide depolymerization

Area of Science:

• Biotechnology
• Biochemistry
• Marine Biology

Background:

• Marine macroalgae are a renewable resource for valuable monosaccharides.
• Enzymatic depolymerization by marine microorganisms is effective for industrial applications.
• Ulvan, a polysaccharide from Ulva, is rich in L-rhamnose and D-glucuronic acid.

Purpose of the Study:

• To develop a high-throughput method for analyzing enzymatic polysaccharide degradation.
• To create a transcription factor-based biosensor specific for L-rhamnose.
• To quantify L-rhamnose release during ulvan degradation.

Main Methods:

• Engineered an E. coli biosensor using the P_rhaBAD promoter for L-rhamnose specificity.
• Optimized the biosensor with a T7 stem-loop and various fluorescent reporters.
• Applied the biosensor to monitor ulvan degradation and analyze Ulva sp. biomass.

Main Results:

• The biosensor demonstrated a linear response for L-rhamnose quantification (10-1000 µM).
• Specificity was confirmed by detecting L-rhamnose only when complete polymer breakdown occurred.
• Successfully applied to analyze L-rhamnose release from diverse Ulva sp. samples.

Conclusions:

• The developed biosensor is a promising tool for high-throughput analysis of polysaccharide degradation.
• It enables reliable quantification of L-rhamnose in complex carbohydrate mixtures.
• Facilitates research into marine polysaccharide utilization for industrial purposes.