title: Use of ionic liquid-based extraction for recovery of salmonella typhimurium and Listeria monocytogenes from food matrices.
abstract: Methods for rapid separation (<5 h) and concentration of bacteria based on solubilization of complex food matrices have been developed recently to facilitate rapid molecular detection methods. However, a major disadvantage of these protocols is the resulting lack of viability of the microorganisms under study due to extensive use of chemicals and enzymes, which can inhibit subsequent quantitative microbiological analyses. In this study, a new class of organic salts, ionic liquids, were used for solubilization of various foodstuffs, with subsequent molecular and microbiological quantification methods. This approach was applied to gram-positive Listeria monocytogenes and gram-negative Salmonella enterica serovar Typhimurium. By introducing the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate into an existing food solubilization protocol, both molecular and microbiological quantification methods could be used subsequently without losing performance or prolonging the analysis. These experiments resulted in an average recovery of 87% of inoculated bacterial cells with real-time PCR, 85% recovery on nonselective agar plates, and 43% on selective medium. These results illustrate the feasibility of applying ionic liquids in sample pretreatment steps for rapid detection and quantification of bacterial pathogens.
authors.affiliation: Christian Doppler Laboratory for Molecular Food Analytics, Vienna, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mester
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
authors.forename: Peter
authors.initials: P
authors.lastname: Rossmanith
mesh_terms: D015169:Colony Count, Microbial / Q000379:methods*; D004269:DNA, Bacterial / Q000032:analysis; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D007093:Imidazoles / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D050296:Microbial Viability; D016133:Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D012995:Solubility; D013045:Species Specificity; D013861:Thiocyanates; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D007093:Imidazoles; D013861:Thiocyanates; C518739:1-ethyl-3-methylimidazolium