Magneto immunoseparation of pathogenic bacteria and electrochemical magneto genosensing of the double-tagged amplicon.
A rapid and sensitive method for the detection of food pathogenic bacteria is reported. In this approach, the bacteria are captured and preconcentrated from food samples with magnetic beads by immunological reaction with the specific antibody against Salmonella. After the lysis of the captured bacteria, further amplification of the genetic material by PCR with a double-tagging set of primers is performed to confirm the identity of the bacteria. Both steps are rapid alternatives to the time-consuming classical selective enrichment and biochemical/serological tests. The double-tagged amplicon is then detected by electrochemical magneto genosensing. The "IMS/double-tagging PCR/m-GEC electrochemical genosensing" approach is used for the first time for the sensitive detection of Salmonella artificially inoculated into skim milk samples. A limit of detection of 1 CFU mL(-1) was obtained in 3.5 h without any pretreatment, in LB broth and in milk diluted 1/10 in LB. If the skim milk is pre-enriched for 6 h, the method is able to feasibly detect as low as 0.04 CFU mL(-1) (1 CFU in 25 g of milk) with a signal-to-background ratio of 20. Moreover, the method is able to clearly distinguish between pathogenic bacteria such as Salmonella and Escherichia coli. The features of this approach are discussed and compared with classical culture methods and PCR-based assay.
Liébana
Susana
S
Grup de Sensors i Biosensors, Departament de Química, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Lermo
Anabel
A
Campoy
Susana
S
Barbé
Jordi
J
Alegret
Salvador
S
Pividori
María Isabel
MI
D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D046508:Culture Techniques; D004269:DNA, Bacterial / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D004563:Electrochemistry; D005516:Food Microbiology; D016680:Genome, Bacterial / Q000235:genetics; D006358:Hot Temperature; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008280:Magnetics; D008855:Microscopy, Electron, Scanning; D008892:Milk / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D019779:Salmonella enterica / Q000166:cytology / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification*; D013997:Time Factors
D004269:DNA, Bacterial