Raman spectroscopy for future planetary exploration: photodegradation, self‐absorption and quantification of carotenoids in microorganisms and mineral matrices. (15th January 2015)

• Record Type: Journal Article
• Authors: Hooijschuur, Jan‐Hein; Verkaaik, Mattheus F.C.; Davies, Gareth R.; Ariese, Freek; Marshall, Craig P.
• Is Part Of: Journal of Raman spectroscopy. Volume 46:Number 10(2015:Oct.)
• Page Start: 856
• Page End: 862
• Publication Date: 2015-01-15
• Subjects: Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.4647
• Languages: English
• ISSNs: 0377-0486

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Carotenoids are among the key biomarkers in the search for life on other planets, and non‐destructive Raman spectroscopy on future rover missions is a potential sensitive detection method, especially under resonant conditions. In this research, reflectance spectra of minerals and microorganisms were measured using ultraviolet/visible diffuse reflectance spectroscopy in order to evaluate potential resonance Raman conditions and the possible degree of sample damage during laser irradiation. We report a photodegradation and semi‐quantitative Raman study of β‐carotene and the carotenoid‐containing extremophile <italic>Deinococcus radiodurans</italic> mixed with calcite at excitation wavelengths of 440 nm, 532 nm and 785 nm. A different type of carotenoid was detected in a culture of <italic>Chroococcidiopsis</italic>. Carotenoids embedded in bacterial membranes were found to be less sensitive to photodegradation than in a mineral matrix. Corrections for self‐absorption effects were performed using the 1085 cm<sup>−1</sup> peak of calcite as an internal standard. Carotenoid‐type signals from 1 mg g<sup>−1</sup><italic>D</italic>. <italic>radiodurans</italic> in calcite could be detected, corresponding to about 5 µg g<sup>−1</sup> β‐carotene in calcite (≈0.5% cell weight). This research emphasizes the potential suitability of Raman spectroscopy in the detection of organic biomarkers in future planetary exploration. Copyright © 2015 John Wiley & Sons, Ltd.</p> </abstract>