A simple, rapid, sensitive method detecting homoserine lactone (HSL)-related compounds in microbial extracts

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• N-acyl homoserine lactones (HSLs) are crucial signaling molecules in bacterial quorum sensing.
• Detecting HSLs in complex environmental samples is challenging due to low concentrations and diverse chemical structures.

Purpose of the Study:

• To develop a simple, rapid, and sensitive assay for detecting HSL-related compounds.
• To assess the prevalence of HSL production in a diverse collection of microbial isolates, including actinomycetes.

Main Methods:

• Established a microtiter plate assay using an Agrobacterium tumefaciens reporter strain with a traG::lacZ/traR gene responsive to exogenous HSLs.
• Quantified beta-galactosidase activity using colorimetric (X-gal) and chemiluminometric (Galacton-Star) substrates.
• Screened crude extracts from 696 microbial isolates and fractionated samples.

Main Results:

• The assay demonstrated high specificity for HSLs.
• 11.64% of crude extracts tested positive for HSLs, with an additional 4.8% showing weak signals.
• Analysis of fractionated samples indicated a significantly higher prevalence, with 50% of tested extracts showing HSL signals.

Conclusions:

• The developed assay is effective for detecting HSLs in microbial extracts.
• A substantial proportion of tested microbial isolates, especially actinomycetes, produce HSL-related compounds, suggesting widespread HSL signaling in nature.
• This study highlights the potential of HSLs in microbial communication within diverse environments.