Microchip coupled with MALDI-TOF MS for the investigation of bacterial contamination of fish muscle products

Bacterial contamination is a significant concern in food safety. Traditional methods, though being a gold stan-dard for bacterial detection, are time-consuming. In this work, we managed to establish a simple and versatile magnetic-assisted microfluidic method for rapid bacterial detection of fish muscle products, by manipulating anti-human IgG functionalized magnetic beads in a zig-zag shaped microfluidic channel, increasing the proba-bility for bacteria capture. The captured bacteria were characterized by matrix-assisted laser desorption ioni-zation time-of-flight mass spectrometry (MALDI-TOF MS). This method is capable of isolating Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae from 5 mu L of sablefish sarcoplasmic protein sample, and detecting Escherichia coli in the range of 6.0 to 6.0x104 CFU/mL with a detection limit of 6 CFU/mL. Bacterial growth on salmon sashimi during its period of storage was successfully monitored. The current protocol holds great po-tential for pathogen detection and microbial control in the food industry.