title: Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum.
abstract: Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions.
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P. O. Box 66, FI-00014 Helsinki, Finland. Electronic address: elias.dahlsten@helsinki.fi.
authors.forename: Elias
authors.initials: E
authors.lastname: Dahlsten
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P. O. Box 66, FI-00014 Helsinki, Finland. Electronic address: miia.lindstrom@helsinki.fi.
authors.forename: Miia
authors.initials: M
authors.lastname: Lindström
authors.affiliation: Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P. O. Box 66, FI-00014 Helsinki, Finland. Electronic address: hannu.korkeala@helsinki.fi.
authors.forename: Hannu
authors.initials: H
authors.lastname: Korkeala
mesh_terms: D003014:Clostridium botulinum / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D005511:Food Handling; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D054712:Salinity; D013312:Stress, Physiological; D013696:Temperature
keywords: Clostridium botulinum; Cold-shock response; Food processing; Foodborne botulism; Heat-shock response