Catalase activity as a biomarker for mild-stress-induced robustness in bacillus weihenstephanensis

Abstract

Microorganisms are able to survive and grow in changing environments by activating stress adaptation mechanisms which may enhance bacterial robustness. Stress-induced enhanced robustness complicates the predictability of microbial inactivation. Using psychrotolerant Bacillus weihenstephanensis strain KBAB4 as a model, we investigated the impact of the culturing temperature on mild-oxidative-stress-induced (cross-)protection toward multiple stresses, including severe oxidative, heat, and acidstresses. Culturing at a refrigeration temperature (7°C) compared to the optimal growth temperature (30°C) affected both the robustness level of B. weihenstephanensis and the oxidative stress adaptive response. Scavengers of reactive oxygen species havea crucial role in adaptation to oxidative stresses, and this points to a possible predictive role in mild-oxidative-stress-inducedrobustness. Therefore, the catalase activity was determined upon mild oxidative stress treatment and was demonstrated to be significantly correlated with the robustness level of mild-stress-treated cells toward severe oxidative and heat stresses but not toward severe acid stress for cells grown at both refrigeration and optimal temperatures. The quantified correlations supportedthe predictive quality of catalase activity as a biomarker and also underlined that the predictive quality is stress specific. Biomarkersthat are able to predict stress-induced enhanced robustness can be used to better understand stress adaptation mechanismsand might allow the design of effective combinations of hurdles to control microbial behavior. © 2013, American Society for Microbiology.