Aptamer-based technology for detecting Bacillus subtilis in soil

Area of Science:

• Microbial Ecology
• Biotechnology
• Agricultural Science

Background:

• Accurate detection and tracking of microbial bioinoculants in soil are crucial for assessing their impact on soil quality and microbial communities.
• Current DNA/RNA-based methods have limitations, creating a need for alternative detection strategies.
• DNA aptamers offer advantages like low cost, stability, and ease of modification for biosensing applications.

Purpose of the Study:

• To isolate and characterize single-strand DNA (ssDNA) aptamers for the specific detection of Bacillus subtilis.
• To validate the efficacy of these aptamers in detecting B. subtilis in various soil types and field conditions.
• To establish aptamers as a viable method for monitoring microbial inoculants in soil.

Main Methods:

• Utilized a toggle-cell SELEX (Systematic Evolution of Ligands by Exponential Enrichment) method to select ssDNA aptamers.
• Characterized aptamer affinity and specificity using kinetic parameters (Kd and Bmax).
• Validated aptamer performance in soils with different physicochemical properties and in field trials.

Main Results:

• Identified two ssDNA aptamers with high affinity (nanomolar Kd) and specificity for B. subtilis strains.
• Demonstrated successful validation of aptamer detection in diverse soil matrices and field conditions.
• Confirmed aptamers' suitability for monitoring B. subtilis inoculants in agricultural soil.

Conclusions:

• Developed the first DNA aptamers capable of binding a specific Bacillus subtilis strain within a bioinoculum formulation.
• Demonstrated the first successful application of DNA aptamers for detecting Bacillus subtilis directly in soil.
• Aptamers represent a promising, practical, and stable method for microbial inoculant detection, supporting sustainable agriculture and regulatory oversight.