Geobacillus stearothermophilus ATCC 7953 spore chemical germination mechanisms in model systems |
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Affiliation: | 1. Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark;2. Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303;3. Department of Chemistry, Faculty of Science, University of Copenhagen, Copenhagen, Denmark;4. Physical Chemistry, Lund University, Lund SE‐221 00, Sweden;5. Department of Antibody Characterization and Analytics, Symphogen A/S, Lyngby, Denmark;1. Doctorado en Modelamiento Matemático Aplicado, Universidad Católica del Maule. Avenida San Miguel 3605, Talca, Chile;2. Facultad de Ciencias Básicas, Universidad Católica del Maule. Avenida San Miguel 3605, Talca, Chile |
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Abstract: | Bacterial endospores through their strong resistance to both chemical and physical hurdles constitute a risk for food industry. Inactivation strategies are based on thermal and/or chemical treatments but rely on incomplete knowledge of the mechanisms of inactivation. Alternative strategies were suggested to achieve food safety while improving product quality. One of them relies on the successive germination and inactivation by pasteurization of bacterial spores. However, to date, a gap of knowledge on bacterial spore germination remains and hinders such an application for food sterilization. Geobacillus stearothermophilus ATCC 7953 spore germination mechanisms were investigated by in situ fluorometry combined with plate counts. G. stearothermophilus spores' inner membrane was stained with Laurdan fluorescent dye. While nutrient pathways showed no strong germination with the combinations tested, successful germination up to 3 log10 could be achieved using 60 mmol l?1 calcium-dipicolinic acid (CaDPA) at 55 °C for 2 h. A model for the CaDPA germination mechanism in two phases could be derived which suggested a potential key role of cortex fragments in the germination path, before completion of the cortex degradation. Additionally, it was confirmed that the germination potential of CaDPA, which does not rely on nutrient receptors, is a widespread germination trigger across spore formers. Understanding germination mechanisms and the limitations of different germination paths is important for the development of multi-hurdle approaches to achieve commercial sterility with reduced thermal load. |
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Keywords: | Bacterial spores Food sterilization Germination Microbial physiology Membrane Modeling CaDPA"} {"#name":"keyword" "$":{"id":"kwrd0045"} "$$":[{"#name":"text" "_":"calcium-dipicolinic acid GP"} {"#name":"keyword" "$":{"id":"kwrd0055"} "$$":[{"#name":"text" "_":"generalized polarization Laurdan"} {"#name":"keyword" "$":{"id":"kwrd0065"} "$$":[{"#name":"text" "_":"6-dodecanoyl-N N-dimethyl-2-naphthylamine |
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