Effects of sporulation media and strain on thermal resistance of Bacillus cereus spores

Abstract

Spores of Bacillus cereus strains ATCC 7004, ATCC 4342 and ATCC 98 18 were produced in four sporulation media (Nutrient Agar supplemented with 1 ppm Mn2+, Fortified Nutrient Agar, Angelotti Medium and Milk Agar) and their percentages of sporulation and heat resistance parameters obtained in a wide temperature range were compared. In all conditions studied, high rates of sporulation were obtained. Clear differences among D-values for spores produced in the four media were observed. The medium which yielded the most resistant spores and the magnitude with which the sporulation medium affected D-values was different for each strain. z-Values of the three strains were not influenced by the medium used to obtain spores.

Behavioural pattern of vegetative cells and spores of Bacillus cereus as affected by time-temperature combinations used in processing of Indian traditional foods

“…The thermal inactivation pattern of spores of B. cereus cultures observed in most of the earlier studies have revealed that D-values differ very much depending primarily on the strains used and to a lesser extent the extrinsic and intrinsic factors. Earlier studies have reported varying D-values for ATCC strains of B. cereus 4342, 7004 and 9818 in buffers and substrates similar to culture broth and those containing food constituents (Mazas et al 1995(Mazas et al , 1999aGonzález et al 1999;Montville et al 2005;Moussa-Boudjemma et al 2006). A similar situation was also reported for a strain of Bacillus anthracis Sterne (Novak et al 2005).…”

Effect of sporulation medium on wet-heat resistance and structure of Alicyclobacillus acidoterrestris DSM 3922-type strain spores and modeling of the inactivation kinetics in apple juice

“…The differences between the D-values may be due to the differences in the test strains, inoculum levels, incubation temperatures, sporulation temperature, differences in nutrient composition and pH of the heating medium, water activity, presence or absence of divalent cations and antimicrobial compounds (Bahçeci and Acar, 2007). Similarly, Mazas et al (1995) determined the thermal resistance characteristics of B. cereus spores sporulated on different types of sporulation media (nutrient agar supplemented with Mn 2+ , fortified nutrient agar, Angelotti medium and milk agar). They found clear differences between the D-values for spores produced in the four media.…”

Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54

“…Extrinsic factors such as medium composition, sporulation temperature and water activity may influence spore properties (Gaillard et al 1998, González et al 1999, Palop et al 1999. The sporulation response to environmental conditions is species and strain specific (Mazas et al 1995, González et al 1999, sometimes even displaying opposite responses for the same factor, as reported for spores of different Bacillus species formed in rich and poor sporulation media (Baril et al 2012).…”

“…Sporulation temperature has a large effect on spore heat resistance of B. cereus with a 10 fold difference in decimal reduction time (D 100°C ) for spores formed at 20 compared to 45⁰C (González et al 1999). Most studies show lower impact of different factors such as sporulation medium, level of nutrients or pH on spore heat resistance, reporting between 1.3 to 6 fold changes in decimal reduction values (D-values) (Mazas et al 1995, Baweja et al 2008, Baril et al 2012). …”

“…The sporulation process and resulting spore properties are affected by environmental conditions (Ryu and Beuchat 2005, Nguyen Thi Minh et al 2011, Sella et al 2014. Environmental parameters described to influence spore heat resistance include medium composition (Mazas et al 1995, Guizelini et al 2012, mineral availability (Bender and Marquis 1985), water activity of the medium (Nguyen Thi Minh et al 2008), sporulation temperature (Baril et al 2011, Marshall et al 2015, oxygen availability and spatial distribution, such as in liquid culture versus agar surface (Veening et al 2006, Rose et al 2007). For example, spores derived from biofilms of B. cereus emetic toxin producing strains grown in polystyrene 96-wells displayed a higher heat resistance compared to spores derived from liquid cultures (van der Voort and Abee 2013).…”