Spectroscopic study of the variation in the pigment profile of the bacterium Deinococcus radiodurans under extreme environmental conditions as bioassinatures for astrobiology

• Grant number: 17/21400-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): November 01, 2017
• Effective date (End): October 31, 2018
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Fabio Rodrigues
• Grantee: Larissa Lopes Cavalcante
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The poliextremophile bacterium Deinococcus radiodurans is considered a model of resistance to radiation, being studied extensively in the context of Astrobiology and missions of search for life in other planets. Among its diverse strategies of radiation protection is the production of photoprotective pigments, which help both in UV protection and oxidant species. Studies show that there are more than 10 carotenoids present in this organism, with deoxyanthine being present in the highest concentration (major carotenoid). As a consequence of their participation in the protection of bacteria exposed to environments with high doses of radiation and oxidizing species, these carotenoids have been proposed as bioassinatures, that is, indicative of biotic activity in life search missions on Mars and, in the future, in other environments.In the present work, the profile study of all carotenoids (major and minor) will be deepened, combining liquid chromatography and spectroscopic techniques such as Raman and UV-Vis spectroscopy. The samples will be exposed to extreme conditions, simulating Martian conditions, maintaining a control sample (cultivated under mild conditions) as a parameter. The changes in the metabolism of the carotenoids in these simulated extraterrestrial conditions will be studied, trying to understand their behavior as bioassinaturas. In addition, a new study of the profile of the metabolites will be made by applying the extreme conditions directly to these molecules, analyzing the alteration of spectroscopic signal as a direct application to the search for bioassinatures. (AU)