title: High-Level Heat Resistance of Spores ofBacillus amyloliquefaciensandBacillus licheniformisResults from the Presence of aspoVAOperon in a Tn1546Transposon.
abstract: Bacterial endospore formers can produce spores that are resistant to many food processing conditions, including heat. Some spores may survive heating processes aimed at production of commercially sterile foods. Recently, it was shown that aspoVAoperon, designatedspoVA2mob, present on a Tn1546transposon inBacillus subtilis, leads to profoundly increased wet heat resistance ofB. subtilisspores. Such Tn1546transposon elements including thespoVA2moboperon were also found in several strains ofBacillus amyloliquefaciensandBacillus licheniformis, and these strains were shown to produce spores with significantly higher resistances to wet heat than their counterparts lacking this transposon. In this study, the locations and compositions of Tn1546transposons encompassing thespoVA2moboperons inB. amyloliquefaciensandB. licheniformiswere analyzed. Introduction of thesespoVA2moboperons intoB. subtilis168 (producing spores that are not highly heat resistant) rendered mutant 168 strains that produced high-level heat resistant spores, demonstrating that these elements inB. amyloliquefaciensandB. licheniformisare responsible for high level heat resistance of spores. Assessment of growth of the nine strains of each species between 5.2°C and 57.7°C showed some differences between strains, especially at lower temperatures, but all strains were able to grow at 57.7°C. Strains ofB. amyloliquefaciensandB. licheniformisthat contain the Tn1546elements (and produce high-level heat resistant spores) grew at temperatures similar to those of their Tn1546-negative counterparts that produce low-level heat resistant spores. The findings presented in this study allow for detection ofB. amyloliquefaciensandB. licheniformisstrains that produce highly heat resistant spores in the food chain.
authors.affiliation: Top Institute Food and NutritionWageningen, Netherlands; Laboratory of Molecular Genetics, University of GroningenGroningen, Netherlands; NIZO Food ResearchEde, Netherlands.
authors.forename: Erwin M
authors.initials: EM
authors.lastname: Berendsen
authors.affiliation: Top Institute Food and NutritionWageningen, Netherlands; NIZO Food ResearchEde, Netherlands.
authors.forename: Rosella A
authors.initials: RA
authors.lastname: Koning
authors.affiliation: Top Institute Food and NutritionWageningen, Netherlands; NIZO Food ResearchEde, Netherlands.
authors.forename: Jos
authors.initials: J
authors.lastname: Boekhorst
authors.affiliation: Top Institute Food and NutritionWageningen, Netherlands; Laboratory of Molecular Genetics, University of GroningenGroningen, Netherlands.
authors.forename: Anne
authors.initials: A
authors.lastname: de Jong
authors.affiliation: Top Institute Food and NutritionWageningen, Netherlands; Laboratory of Molecular Genetics, University of GroningenGroningen, Netherlands.
authors.forename: Oscar P
authors.initials: OP
authors.lastname: Kuipers
authors.affiliation: Top Institute Food and NutritionWageningen, Netherlands; NIZO Food ResearchEde, Netherlands.
authors.forename: Marjon H J
authors.initials: MH
authors.lastname: Wells-Bennik
keywords: Tn1546 transposon; genome analysis; heat resistance; spoVA operon; spores