Capture and identification of bacteria from fish muscle based on immunomagnetic beads and MALDI-TOF MS

Abstract

In the present study, <i>E. coli</i> was taken as a model bacterium, anti-<i>E. coli</i> functionalized magnetic beads were constructed and used to capture <i>E. coli</i> from aqueous extracts of fish sarcoplasmic protein (FSP) and fish muscle protein of sablefish. The excellency of the reproducibility of the present protocol was demonstrated by capturing <i>E. coli</i> from sablefish FSP extracts. The presence of 10 CFU/mL <i>E. coli</i> is still detectable. A microbial safety test on the surface of fish muscle was successfully performed. The bacterial identification accuracy from samples with different matrices was found to be excellent with RSD = 3%. High specific detection of target bacteria in complex biological samples was testified by spiking <i>Staphylococcus aureus</i> and <i>Klebsiella pneumoniae</i> in samples as interference. Ten biomarker ions were discovered for <i>E. coli</i>'s recognition. It is promising to apply the present protocol in bacterial analysis in muscle food samples to ensure their safety.