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Effects of Mn2+ levels on the resistance properties of Bacillus cereus spores

  • Klobutcher A
Journal of Bacteriology Research (2013) 5(1) 9-12
DOI: 10.5897/jbr12.031
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Abstract

In some Bacillus species, manganese levels influence the resistance properties of spores. To determine if this was true for Bacillus cereus, bacteria were sporulated with different MnCl 2 concentrations resulting in spores with 30-fold differences in core Mn 2+ levels. Spores with different Mn 2+ levels displayed no differences in resistance to dry heat, UV radiation, γ γ γ γ-radiation, or hydrogen peroxide. However, spores with the lowest Mn 2+ level were less resistant to wet heat. Overall, Mn 2+ levels were not a major factor in B. cereus spore resistance, and this suggests that this will also be true for the closely related B. anthracis spores.

Figures

  • Table 1. Levels of Mn 2+ in spores prepared in media with different amounts of added MnCl2*.
  • Figure 1. Resistance properties of B. cereus spores with different Mn contents. Plots illustrating survival of B. cereus spores prepared with varying MnCl2 concentrations following treatment with (a) dry heat at 120°C, (b) UVC radiation at 5x10 -4 J min -1 cm -2 , (c) varying doses of γ-radiation measured in kiloGrays (kGy), (d) H2O2 (5% in 25 mM KPO4 buffer (pH 7.4) at 23°C) and, (e) wet heat at 87°C are shown. All values were ≤ +/- 20%, and all resistance measurements were made at least twice, with at least duplicate determinations at each time point. The symbols denoting the MnCl2 added to the sporulation medium are: () 0.5 µmol l -1 ; ( ) 1 µmol l -1 ; ( ) 10 µmol l -1 ; and ( ) 100 µmol l -1 . Spores of B. cereus T (originally obtained from H.O. Halvorson) were prepared at 37°C in liquid medium with different levels of added MnCl2, and harvested and purified as described (Stewart et al., 1981; Ghosh and Setlow, 2010). These spores were free (> 98%) of growing or sporulating cells, germinated spores and cell debris as determined by phase contrast microscopy. Prior to analyses of spore resistance, spore preparations were incubated for 1 h with 10 mM EDTA at 4°C, and then washed thoroughly with water and stored in water at 4°C protected from light. Measurements of spore killing by wet heat, dry heat, UVC radiation, γ-radiation in liquid, or hydrogen peroxide were all carried out as described (Ghosh et al., 2011; Granger et al., 2011).

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APA

Klobutcher, A. (2013). Effects of Mn2+ levels on the resistance properties of Bacillus cereus spores. Journal of Bacteriology Research, 5(1), 9–12. https://doi.org/10.5897/jbr12.031

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