Molecular detection of Clostridium and Bacillus species in foods: recent advances and applications

Spore-forming bacteria, especially Clostridium spp. and Bacillus spp., are ubiquitous in food systems, and their ingestion can cause serious diseases in humans and animals. Their persistence in diverse food matrices and resistance to conventional treatments make rapid and accurate detection essential for effective monitoring and control. Traditional culture-based and biochemical assays remain the standard for identifying these bacteria but are often time-consuming, labor-intensive and limited in sensitivity. In contrast, nucleic acid-based methods provide rapid, specific and sensitive alternatives by directly targeting genetic markers of pathogenic or spoilage strains. This review summarizes how nucleic acid methods, including PCR, FISH, LAMP, RPA, WGS, and the emerging CRISPR/Cas systems, have been applied specifically to detect Clostridium spp. and Bacillus spp. in food systems. Each method offers unique advantages and limitations. PCR-based methods enable accurate quantification but require thermal cycling. FISH-based methods are simple but require microscopy and have limited validation in food. WGS-based methods provide strain-level characterization but depend on informatics and specialized equipment. Isothermal techniques such as LAMP- and RPA-based methods allow rapid field detection but involve complex primer design or poor discrimination of closely related genes. CRISPR/Cas-based platforms further enhance simplicity, specificity, sensitivity for on-site detection, though the validation for spore-forming bacteria remains limited. Overall, this review provides an overview of gene targets, methodological adaptations, and analytical performance of nucleic acid-based assays for detecting Clostridium spp. and Bacillus spp., highlighting current progress and future opportunities for improving food safety monitoring.