Detection of Escherichia coli in Food Samples by Magnetosome-based Biosensor

Abstract

The rising cases of food poisoning and traveler’s diarrhea through Escherichia coli infection are a global concern. Magnetosome is biogenic magnetic nanoparticles extracted from magnetotactic bacteria and magnetosome-based biosensors offer simple and rapid detection of microbial pathogens. The current study demonstrates the application of a magnetosome-antibody complex-based biosensor for the detection of antigenic O-polysaccharide and E. coli from contaminated food samples. The magnetosome (1, 2 mg/mL)-antibody (0.8–200 µg/mL) complex was initially coupled with lipopolysaccharide (5 µg/mL) through antibody-antigen interaction. The magnetosome (1, 2 mg/mL)-antibody (0.8–200 µg/mL)-lipopolysaccharide (5 µg/mL) complexes were collected via external magnet and confirmed through spectroscopy studies. The magnetosome (1, 2 mg/mL)-antibody (0.8–200 µg/mL) complexes were applied to different concentration of lipopolysaccharide (0.01–50 µg/mL). The concentrated magnetosome (2 mg/ mL)-antibody (1.6 µg/mL) complex and lipopolysaccharide (0.1 µg/mL) were established in ELISA. Further, the magnetosome-antibody complex was applied on a screen-printed carbon electrode and stabilized through an external magnet. The least concentration of lipopolysaccharide (0.5 µg/mL) was determined in impedance. Further, the magnetosome-based biosensor was applied to various contaminated food samples- milk, water, and pineapple juice and the extracted lipopolysaccharide were selectively detected. The biosensor did not display any cross-reactivity and therefore exhibits specificity. The active E. coli (10¹ CFU/mL) from milk and water samples were also rapidly detected within 30 min by the developed biosensor. Furthermore, the field emission scanning electron microscope images confirmed the efficient detection of E. coli from the food sample.