The Response of Bacillus subtilis to Simulated Martian Conditions and to the Space Environment

Abstract

Bacillus subtilis is a non-pathogenic, gram-positive, rod-shaped, aerobic, ubiquitous bacterium that is commonly found in soil. It has become widely adopted as a model organism for laboratory studies on the survivability under extreme conditions like those on Mars. The metabolically inactive resting form of this bacterium, the spore, is usually more resistant to various environmental stresses than its counterpart, the vegetative form. Its genome is completely sequenced and the genetics and physiology of DNA protection and repair is well understood. The high resistance of B. subtilis spores is mainly due to a dehydrated, highly mineralised core enclosed in a thick protective envelop, the cortex and the spore coat layers, and the saturation of their DNA with small, acid-soluble proteins whose binding greatly alters the chemical and enzymatic reactivity of the DNA (Setlow, 1995)