title: A rapid method for the detection of foodborne pathogens by extraction of a trace amount of DNA from raw milk based on amino-modified silica-coated magnetic nanoparticles and polymerase chain reaction.
abstract: A method based on amino-modified silica-coated magnetic nanoparticles (ASMNPs) and polymerase chain reaction (PCR) was developed to rapidly and sensitively detect foodborne pathogens in raw milk. After optimizing parameters such as pH, temperature, and time, a trace amount of genomic DNA of pathogens could be extracted directly from complex matrices such as raw milk using ASMNPs. The magnetically separated complexes of genomic DNA and ASMNPs were directly subjected to single PCR (S-PCR) or multiplex PCR (M-PCR) to detect single or multiple pathogens from raw milk samples. Salmonella Enteritidis (Gram-negative) and Listeria monocytogenes (Gram-positive) were used as model organisms to artificially contaminate raw milk samples. After magnetic separation and S-PCR, the detection sensitivities were 8 CFU mL(-1) and 13 CFU mL(-1) respectively for these two types of pathogens. Furthermore, this method was successfully used to detect multiple pathogens (S. Enteritidis and L. monocytogenes) from artificially contaminated raw milk using M-PCR at sensitivities of 15 CFU mL(-1) and 25 CFU mL(-1), respectively. This method has great potential to rapidly and sensitively detect pathogens in raw milk or other complex food matrices.
authors.affiliation: MOST-USDA Joint Research Center for Food Safety & Bor Luh Food Safety Center, School of Agriculture and Biology & State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai 200240, PR China. yalung@foxmail.com
authors.forename: Yalong
authors.initials: Y
authors.lastname: Bai
authors.forename: Minghui
authors.initials: M
authors.lastname: Song
authors.forename: Yan
authors.initials: Y
authors.lastname: Cui
authors.forename: Chunlei
authors.initials: C
authors.lastname: Shi
authors.forename: Dapeng
authors.initials: D
authors.lastname: Wang
authors.forename: George C
authors.initials: GC
authors.lastname: Paoli
authors.forename: Xianming
authors.initials: X
authors.lastname: Shi
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000032:analysis*; D005517:Foodborne Diseases / Q000175:diagnosis / Q000517:prevention & control; D008089:Listeria monocytogenes / Q000302:isolation & purification; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008892:Milk / Q000737:chemistry / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012477:Salmonella enteritidis / Q000302:isolation & purification; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004269:DNA, Bacterial; D058185:Magnetite Nanoparticles; D012822:Silicon Dioxide
keywords: Amino-modified silica-coated magnetic nanoparticles; Listeria monocytogenes; Milk; Pathogens; Polymerase chain reaction; Salmonella Enteritidis