Effect of Temperature on the Cannibalistic Behavior of Bacillus subtilis

Bacillus subtilis resorts to cannibalism to delay sporulation under severe nutritional limitation. We report the effect of temperature on the dynamics of cannibalism demonstrated by B. subtilis. A model consisting of a delay differential equation may explain the effect of temperature on the dynamics of cannibalism. Cannibalism as a strategy offers a valuable resource for mi-croorganisms that are limited by nutrients. Bacillus subtilis, a soil microorganism, has been shown to resort to cannibalism and predation under conditions of limited nutritional availabil-ity (5). B. subtilis normally forms spores under stress condi-tions. However, sporulation is an energy-intensive process and requires a minimal amount of nutrients to be present. The cells commit to sporulation only when they are certain about the impending stress. B. subtilis has therefore evolved strategies to delay sporulation (2). Cannibalism by B. subtilis is shown to be initiated by an extracellular killing factor and an intracellular signaling protein that acts cooperatively to cause death among sister cells in a population and impede sporulation. Environ-mental changes are known to have an effect on the cannibal-istic behavior of species. Abiotic factors like temperature alter the interaction between species in ecology and affect the pop-ulation dynamics. Here, we study the effect of temperature on the cannibalistic behavior of B. subtilis. We demonstrate that the cannibalistic property of B. subtilis under extreme nutrient deficiency is dependent on the medium temperature. We an-alyzed the data by proposing a model using a delay differential equation. The wild-type B. subtilis strain 168trpC2 was used in this work (5). The mutant strain B. subtilis IRN 235/238 wa