Development of a portable colorimetric point-of-care device for the detection of Bacillus cereus in food specimens

Bacillus cereus is recognized as a major foodborne pathogen that causes food poisoning and other types of infections. The development of a cost-effective and sensitive assay for the detection of this pathogenic microorganism is essential to mitigate the risk of contamination, particularly as a point-of-care device in resource-poor settings. In this study, a gelatin-based colorimetric assay was designed for the rapid detection of B. cereus in food. The multi-layer 3D-printed set-up incorporates a gelatin film of a specific concentration (10% (w/v)) that is then liquefied owing to the gelatinase activity of B. cereus. The liquefied sample passes through the colored layer causing the dye to migrate towards the bottom-placed absorption layer, thereby generating a positive colorimetric signal. The detection range of the assay (10²-10³ Colony-Forming Unit (CFU)/mL B. cereus) is comparable to the available methods of detection, which rely on the usage of expensive procedures. Hence, the developed assay represents a low-cost, simple, and portable point-of-care device to sensitively detect B. cereus in food specimens.