title: Development of matrix lysis for concentration of gram positive bacteria from food and blood.
abstract: The development of a fast, reliable and inexpensive protocol for the concentration of bacteria from food by the removal of fat, carbohydrates and proteins that is compatible with downstream alternative DNA-based quantification methods is described. The protocol was used for dairy products, cooked and smoked fish and meat, carbohydrate-rich cooked products, ready-to-eat sauces, egg and blood. Lysis resulted in pellets of reasonable size for further processing. Starch, plant materials, fungi, tissues such as sinew, and chalaza could not be dissolved. Using L. monocytogenes, S. aureus and B. cereus as model organisms, microscopic analysis of the remaining bacterial pellets revealed that the recovered bacteria remained physically intact, albeit that the viability of the cells was compromised. Using real-time PCR, 7.3 CFU of L. monocytogenes were detected in artificially contaminated ultra-high temperature treated (UHT) milk and raw milk.
authors.affiliation: Institute of Milk Hygiene, Milk Technology and Food Science, Department of Veterinary Public Health and Food Science, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria. peter.rossmanith@vu-wien.ac.at
authors.forename: Peter
authors.initials: P
authors.lastname: Rossmanith
authors.forename: Beate
authors.initials: B
authors.lastname: Süss
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Hein
mesh_terms: D000818:Animals; D001769:Blood / Q000382:microbiology*; D002021:Buffers; D002241:Carbohydrates / Q000737:chemistry; D003611:Dairy Products / Q000382:microbiology; D003902:Detergents / Q000494:pharmacology*; D005399:Fishes / Q000382:microbiology; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination; D005516:Food Microbiology; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D008055:Lipids / Q000737:chemistry; D008089:Listeria monocytogenes / Q000235:genetics / Q000302:isolation & purification; D008460:Meat / Q000382:microbiology; D008892:Milk / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D011506:Proteins / Q000737:chemistry; D012995:Solubility; D012997:Solvents / Q000494:pharmacology*
chemical_list: D002021:Buffers; D002241:Carbohydrates; D003902:Detergents; D008055:Lipids; D011506:Proteins; D012997:Solvents