title: Variability in DPA and Calcium Content in the Spores ofClostridiumSpecies.
abstract: Spores of a number of clostridial species, and their resistance to thermal treatment is a major concern for the food industry. Spore resistance to wet heat is related to the level of spore hydration, which is inversely correlated with the content of calcium and dipicolinic acid (DPA) in the spore core. It is widely believed that the accumulation of DPA and calcium in the spore core is a fundamental component of the sporulation process for all endospore forming species. We have noticed heterogeneity in the heat resistance capacity and overall DPA/calcium content among the spores of several species belonging toClostridium sensu strictogroup: twoC. acetobutylicumstrains (DSM 792 and 1731), twoC. beijerinckiistrains (DSM 791 and NCIMB 8052), and aC. collagenovoransstrain (DSM 3089). AC. beijerinckiistrain (DSM 791) and aC. acetobutylicumstrain (DSM 792) display low Ca and DPA levels. In addition, these two species, with the lowest average Ca/DPA content amongst the strains considered, also exhibit minimal heat resistance. There appears to be no correlation between the Ca/DPA content and the phylogenetic distribution of theC. acetobutylicumandC. beijerinckiispecies based either on the 16S rRNA or thespoVA gene. This finding suggests that a subset ofClostridium sensu strictospecies produce spores with low resistance to wet heat. Additionally, analysis of individual spores using STEM-EDS and STXM revealed that DPA and calcium levels can also vary amongst individual spores in a single spore population.
authors.affiliation: Swiss Federal Institute of Technology in Lausanne (EPFL)Lausanne, Switzerland; Institute of Molecular Biology, Slovak Academy of SciencesBratislava, Slovakia.
authors.forename: Jan
authors.initials: J
authors.lastname: Jamroskovic
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences Bratislava, Slovakia.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Chromikova
authors.affiliation: Swiss Federal Institute of Technology in Lausanne (EPFL) Lausanne, Switzerland.
authors.forename: Cornelia
authors.initials: C
authors.lastname: List
authors.affiliation: Swiss Federal Institute of Technology in Lausanne (EPFL) Lausanne, Switzerland.
authors.forename: Barbora
authors.initials: B
authors.lastname: Bartova
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences Bratislava, Slovakia.
authors.forename: Imrich
authors.initials: I
authors.lastname: Barak
authors.affiliation: Swiss Federal Institute of Technology in Lausanne (EPFL) Lausanne, Switzerland.
authors.forename: Rizlan
authors.initials: R
authors.lastname: Bernier-Latmani
keywords: Clostridium sensu stricto; STEM-EDS; STXM; SpoVA; dipicolinic acid; phylogeny; sporulation; wet heat resistance