Insights into the Structure and Protein Composition of Spores Formed at Different Temperatures.

The bacterium produces the most heat-resistant spores of any spoilage-causing microorganism known in the food industry. Previous work by our group revealed that the resistance of these spores to wet heat and biocides was lower when spores were produced at a lower temperature than the optimal temperature. Here, we used electron microcopy to characterize the ultrastructure of the coat of the spores formed at different sporulation temperatures; we found that spores produced at 55 °C mainly exhibited a lamellar inner coat tightly associated with a diffuse outer coat, while spores produced at 45 °C showed an inner and an outer coat separated by a less electron-dense zone.

Temperature impacts the sporulation capacities and spore resistance of Moorella thermoacetica.

Temperatures encountered in cannery allow growth of thermophilic spore-forming bacteria, including the strictly anaerobe Moorella thermoacetica, which grows optimally from 55 °C to 65 °C and is the main cause of spoilage of low-acid canned foods (LACFs) at high temperature. Resistance to wet-heat, biocides and UV-C of spores formed at different temperatures was assessed either for a selection of M. thermoacetica strains or for the strain M.