Abstract
The food industry requires rapid and simple detection methods for preventing harm from pathogenic bacteria. Until now, various technologies used to detect foodborne bacteria were time-consuming and laborious. Therefore, we have developed an automated immunomagnetic separation combined with a colorimetric assay for the rapid detection of E. coli O157:H7 in food samples. The colorimetric detection method using enzymatic reaction is fascinating because of its simplicity and rapidity and does not need sophisticated devices. Moreover, the proposed procedures for the detection of bacteria in food take less than 3 h including pre-enrichment, separation and detection steps. First, target-specific immunomagnetic beads were introduced to contaminated milk in a pre-enrichment step. Second, the pre-enriched sample solution containing target bacteria bound on immunomagnetic beads was injected into an automated pretreatment system. Subsequently, the immunomagnetic beads along with target bacteria were separated and concentrated into a recovery tube. Finally, released β-galactosidase from E. coli O157:H7 after lysis was reacted with chlorophenol red β-galactopyranoside (CPRG) used as a substrate and the colorimetric change of CPRG was determined by absorbance measuring or the naked eye. By the proposed approach in this study, we could detect 3 × 102 CFU/mL of E. coli O157:H7 from a milk sample within 3 h.
Highlights
Enterohemorrhagic Escherichia coli O157:H7 (E. coli O157:H7) is one of the major foodborne pathogens producing cytotoxins such as verotoxin and shiga toxin
The absorbance of CPR dramatically increased from 105 CFU/mL in the bacteria concentration-depending manner. These results indicated that the concentration of target bacteria at the lysis step should be higher than 105 CFU/mL to identify the presence of E. coli O157:H7 by the enzyme reaction-based colorimetric changes
The advantage of the combined is the of target bacteria in quantitative manner through numerical from absorbance process is the detection of target abacteria in a easy quantitative manner through values from
Summary
Enterohemorrhagic Escherichia coli O157:H7 (E. coli O157:H7) is one of the major foodborne pathogens producing cytotoxins such as verotoxin and shiga toxin. Control and Prevention (CDC), transmission of E. coli O157:H7 causing food poisoning is primarily occurred by contaminated food and water. They become a direct cause for increasing financial losses for both the food industry and the consumer [1,2,3]. Traditional methods for detecting foodborne bacteria can take a few days because these include long enrichment steps for a large sample volume consisting of 25 g of a food sample and 225 mL of a buffer solution, plating to a selective agar and biochemical reaction procedures [4,5,6]. The methods consist of laborious experimental steps for confirming the bacteria cells and require a trained person to perform the test [7,8]. A nanoporous membrane-based impedimetric sensor was developed for the detection of
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