Degradation of Β-carotene under Uv-rich Irradiation Conditions: Implications for Martian Environment

Introduction: If life ever evolved on Mars, it could leave molecular remnants – biomarkers which can be preserved within the Martian geological environment. It has been demonstrated that the survival of extremophiles in stressed terrestrial environments fundamentally depends upon their synthesis of a specialized suite of protective biochemicals in response to desiccation, low-wavelength high-energy radiation insolation, extremes of pH, temperature and pressure and high concentration of toxic heavy metal ions [1-3]. Such molecules could serve as potential biomarkers. One group of these protective biochemicals is carotenoids that serve both as light-harvesting pigment and also as cellular DNA damage-repair agents [4]. Thus, β-carotene, widely found in variety of halophilic species on Earth, could be a significant biomarker. It is known, that the molecule of β-carotene is sensitive to solar radiation, heating, as well as to reactive oxygen species (for example [5]). Thus the question arises – may it be preserved on Mars? In this study we have exposed pure β-carotene to the light obtained by metal halide lamp in order to simulate Mars irradiation mainly in the UV region. The protective role of the mineral matrix was also studied and is further discussed.