title: Effects of nisin and reutericyclin on resistance of endospores of Clostridium spp. to heat and high pressure.
abstract: The effects of high pressure, temperature, and antimicrobial compounds on endospores of Clostridium spp. were examined. Minimal inhibitory concentrations (MIC) of nisin and reutericyclin were determined for vegetative cells and endospores of Clostridium sporogenes ATCC 7955, Clostridium beijerinckii ATCC 8260, and Clostridium difficile 3195. Endospores of C. sporogenes ATCC 7955 and C. beijerinckii ATCC 8260 were exposed to 90 °C and 90 °C/600 MPa in the presence of 16 mg L(-1) nisin or 6.4 mg L(-1) reutericyclin for 0-60 min in a 0.9% saline solution. Dipicolinic acid (DPA) release was measured using a terbium-DPA fluorescence assay, and endospore permeability was assessed using 4',6-diamidino-2-phenylindole (DAPI) fluorescence. Vegetative cells of C. sporogenes ATCC 7955 exhibited higher sensitivity to nisin relative to endospores, with MIC values 0.23 ± 0.084 mg L(-1) and 1.11 ± 0.48 mg L(-1), respectively. Nisin increased DPA release when endospores were treated at 90 °C; however, only C. sporogenes ATCC 7955 exhibited higher inactivation, suggesting strain or species specific effects. Reutericyclin did not enhance spore inactivation or DPA release. Use of nisin in combination with high pressure, thermal treatments enhanced inactivation of endospores of Clostridium spp. and may have application in foods.
authors.affiliation: University of Alberta, Department of Agricultural, Food and Nutritional Science, 4-10 Agriculture Forestry Centre, Edmonton, Alberta, Canada T6G 2P5. simmon@ualberta.ca
authors.forename: Simmon
authors.initials: S
authors.lastname: Hofstetter
authors.forename: David
authors.initials: D
authors.lastname: Gebhardt
authors.forename: Linda
authors.initials: L
authors.lastname: Ho
authors.forename: Michael
authors.initials: M
authors.lastname: Gänzle
authors.forename: Lynn M
authors.initials: LM
authors.lastname: McMullen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003013:Clostridium / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development; D006358:Hot Temperature; D050296:Microbial Viability / Q000187:drug effects; D009561:Nisin / Q000494:pharmacology*; D011312:Pressure; D013171:Spores, Bacterial / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development; D013720:Tenuazonic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; C416127:reutericyclin; D009561:Nisin; D013720:Tenuazonic Acid