AUTHOR=Butler Robert R. , Schill Kristin M. , Wang Yun , Pombert Jean-François 

TITLE=Genetic Characterization of the Exceptionally High Heat Resistance of the Non-toxic Surrogate Clostridium sporogenes PA 3679

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00545

DOI=10.3389/fmicb.2017.00545

ISSN=1664-302X

ABSTRACT=<p><italic>Clostridium sporogenes</italic> PA 3679 is a non-toxic endospore former that is widely used as a surrogate for <italic>Clostridium botulinum</italic> by the food processing industry to validate thermal processing strategies. PA 3679 produces spores of exceptionally high heat resistance without botulinum neurotoxins, permitting the use of PA 3679 in inoculated pack studies while ensuring the safety of food processing facilities. To identify genes associated with this heat resistance, the genomes of <italic>C. sporogenes</italic> PA 3679 isolates were compared to several other <italic>C. sporogenes</italic> strains. The most significant difference was the acquisition of a second <italic>spoVA</italic> operon, <italic>spoVA2</italic>, which is responsible for transport of dipicolinic acid into the spore core during sporulation. Interestingly, <italic>spoVA2</italic> was also found in some <italic>C. botulinum</italic> species which phylogenetically cluster with PA 3679. Most other <italic>C. sporogenes</italic> strains examined both lack the <italic>spoVA2</italic> locus and are phylogenetically distant within the group I <italic>Clostridium</italic>, adding to the understanding that <italic>C. sporogenes</italic> are dispersed <italic>C. botulinum</italic> strains which lack toxin genes. <italic>C. sporogenes</italic> strains are thus a very eclectic group, and few strains possess the characteristic heat resistance of PA 3679.</p>