Effects of Mn levels on resistance of Bacillus megaterium spores to heat, radiation and hydrogen peroxide

Abstract

Aims: To determine the effects of Mn levels in Bacillus megaterium sporulation and spores on spore resistance. Methods and Results: Bacillus megaterium was sporulated with no added MnCl2 and up to 1 mmol l−1 MnCl2. The resultant spores were purified and loosely bound Mn removed, and spore Mn levels were found to vary c. 100‐fold. The Mn level had no effect on spore γ‐radiation resistance, but B. megaterium spores with elevated Mn levels had higher resistance to UVC radiation (as did Bacillus subtilis spores), wet and dry heat and H2O2. However, levels of dipicolinic acid and the DNA‐protective α/β‐type small, acid‐soluble spore proteins were the same in spores with high and low Mn levels. Conclusions: Mn levels either in sporulation or in spores are important factors in determining levels of B. megaterium spore resistance to many agents, with the exception of γ‐radiation. Significance and Impact of the Study: The Mn level in sporulation is an important factor to consider when resistance properties of B. megaterium spores are examined, and will influence the UV resistance of B. subtilis spores, some of which are used as biological dosimeters.

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 major factors that contribute to the wet heat resistance of spores are the core water content, mineralization of the spore core due to accumulation of high levels of divalent cations and DPA and the presence of high levels α/β type small acid soluble proteins (SASP) in the spore core (Melly et al, 2002). Also, the levels of Mn and the maturation of released spores during sporulation affect wetheat resistance (Ghosh et al, 2011;Sanchez-Salas et al, 2011).…”

Escherichia coli Genes and Pathways Involved in Surviving Extreme Exposure to Ionizing Radiation

“…The requirements for genes involved in protein stability and turnover, as well as those involved in oxidative stress signaling, can likely be understood in the context of current research from the Daly and Radman groups that indicates that protein oxidation is a major deleterious effect of IR (21,24,44,79,80). As is the case for DNA, proteins are a target of IR-mediated damage.…”

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

“…Other metals present in the SS material are chromium (18 %) and nickel (8 %). Previously, a positive correlation was found between high manganese content and wet heat resistance (at 85 °C) of Bacillus megaterium spores (Ghosh et al 2011). Notably, a high iron content was linked to reduced resistance of Clostridium botulinum spores when heated at 95-110 °C (Kihm et al 1990).…”

“…Cations reported to increase heat resistance are calcium, potassium, magnesium and manganese (Cazemier et al 2001, Oomes andBrul 2004), albeit that effects are species-specific. For example, spore heat resistance of B. megaterium increased with manganese content in the spore core (Ghosh et al 2011) but not of B. subtilis spores (Granger et al 2011). Spore heat resistance seems to be more affected by a combined effect of multiple metals compared to single metals (Cazemier et al 2001, Oomes andBrul 2004).…”

“…In B. subtilis the spore manganese content was proposed as a biomarker for high heat resistance (Rebelo Lima 2012). High levels of manganese in the medium resulted in B. megaterium spores with much higher resistance towards several inactivating treatments, including wet and dry heat (Ghosh et al 2011). Even though the main component of SS material is iron (>70 %), it also contains manganese (1 %).…”