Detection of Salmonella spp. using microsphere-based, fiber-optic DNA microarrays

Area of Science:

• Food safety and microbiology
• Biotechnology and biosensing
• Molecular diagnostics

Background:

• Salmonella spp. pose a significant public health risk as a leading cause of foodborne illness.
• Contamination of meat, poultry, and eggs by Salmonella necessitates effective food safety monitoring.
• Current methods for Salmonella detection require improvement in speed and sensitivity.

Purpose of the Study:

• To develop a novel fiber-optic DNA microarray for the rapid and sensitive detection of Salmonella spp.
• To utilize microsphere-immobilized oligonucleotide probes targeting specific Salmonella genes (invA and spvB).
• To evaluate the performance of the developed microarray for food safety applications.

Main Methods:

• Fabrication of fiber-optic DNA microarrays by immobilizing oligonucleotide probes on microspheres within etched optical fiber bundle microwells.
• Detection of Salmonella DNA via a sandwich-type assay using Cy3-labeled secondary probes for visualization.
• Testing the microarray's sensitivity, specificity, and performance with bacterial mixtures.

Main Results:

• The fiber-optic DNA microarray successfully detected Salmonella spp. at concentrations of 10(3)-10(4) colony-forming units/mL after 1-hour hybridization without amplification.
• The assay demonstrated high specificity, showing no cross-reactivity with common foodborne pathogens like E. coli and Y. enterocolitica.
• Detection of Salmonella in mixed bacterial cultures was achieved with only a moderate loss in sensitivity.

Conclusions:

• Fiber-optic DNA microarrays provide a viable platform for rapid and sensitive detection of Salmonella spp. in food safety contexts.
• The adaptable nature of fiber-optic microarrays allows for potential simultaneous detection of multiple foodborne pathogens.
• This technology holds promise for enhancing food safety protocols and public health protection against foodborne diseases.