Development of Novel DNA Fluorescence In Situ Hybridization Probes for Rapid Detection of Microbial Contaminants in Cosmetic Products

Introduction: Microbial contamination in the cosmetic industry represents a significant risk to product safety, potentially causing health issues for consumers and leading to costly recalls. Common contaminants, such as Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, can be introduced during manufacturing or consumer use, resulting in contaminations and product spoilage. Conventional detection methods commonly used, like plate counting, are slow, often taking up to a week to yield results, which delays quality control processes and increases analysis costs. The Fluorescence In Situ Hybridization (FISH) technique offers a faster, specific, and sensitive alternative for directly detecting microorganisms in cosmetic products. This study aims to design and validate new DNA-FISH probes, optimized to function without formamide, for the rapid identification of cosmetic microbial contaminants. Methods: In silico probes targeting E. coli, P. aeruginosa, and S. aureus were designed using the DECIPHER program, which included sequence alignment, as well as assessments for specificity and efficiency. The 23S ribosomal RNA gene was selected due to its high variability and functional relevance, making it an ideal target for specific identification. Probes were evaluated both in silico and experimentally with target and non-target microorganisms. The FISH procedure was optimized to exclude formamide, a commonly used but toxic solvent in FISH protocols, thereby enhancing safety and usability. Results: The designed probes demonstrated high specificity and efficiency for detecting the target microorganisms in both in silico and experimental conditions. Experimental validation confirmed that the probes could reliably identify E. coli, P. aeruginosa, and S. aureus in controlled cultures, producing fluorescent signals without the need for formamide. Conclusions: This study successfully developed formamide-free DNA-FISH probes for the rapid identification of key microbial contaminants in cosmetic products. The proposed method addresses the limitations of traditional microbiological testing by providing quicker, safer, and more reliable results, thereby improving quality control processes and product safety in the cosmetic industry.