Detecting pigments from gypsum endoliths using Raman spectroscopy: From field prospection to laboratory studies

Abstract

Microbial colonisations of gypsum from different sites from Southern Sicily and Eastern Poland were investigated using laboratory-based Raman microspectrometers and portable Raman spectrometric devices. Selected zones of microbial colonisations of few types of gypsum are described from the point of view of the presence of algae and cyanobacteria. Macrocrystalline gypsum layers in Sicily and Eastern Poland originate from Tertiary sedimentary series. In Southern Sicily gypsum outcrops from late Miocene age were investigated near Scala dei Turchi, Torre Salsa and Siculiana Marina. Polish Tertiary Middle Miocene age examples of gypsum colonisations of decimetre to metre long outcropping gypsum crystals were studied near Chotel Czerwony, Skorocice and Chwalowice. Common microbial pigments were detected: carotenoids were documented in majority of the samples (common Raman bands at around 1525, 1157 and 1004 cm À1 ), Raman spectra of other pigments were recorded in several zones using near infrared excitation (785 nm): chlorophyll (1326, 1285, 1188 and 745 cm À1 ), scytonemin (1593, 1552, 1438 and 1173 cm À1 ) and phycobiliproteins (1275 cm À1 ). Raman microspectrometric investigations of colonisations allow to gather detailed information about pigment distribution in micrometric zones of gypsum samples. Portable instrumentation permits also detection of carotenoids. Observed shifts of positions of Raman features of carotenoids between gypsum samples (and sites worldwide) and relative to reference values are discussed and critically evaluated.

Raman spectroscopic search for scytonemin and gloeocapsin in endolithic colonizations in large gypsum crystals

“…In the first study, mostly green and brown areas of the layered systems were investigated and Raman features documented the presence of chlorophyll (especially common in green), carotenoids (found in all the coloured zones), scytonemin (encountered in the dark zones) and also phycobiliproteins. More detail on the distribution of carotenoids was recently collected [53] on endoliths from Southern Sicily, and three newly observed sites of cyanobacterial colonization in large gypsum crystals in Eastern Poland were included. Raman spectra document the presence of different carotenoids in the samples, with their highest amount being found in the brick-coloured strata corresponding to β-carotene exclusively, in the case of samples colonized by the filamentous green alga Trentepohlia at Chotel Czerwony.…”

GeoRaman

“…In recent years, the study of the biocolonization of minerals and rocky areas has taken on great importance, both in the area of art and archaeology, as well as in issues related to the possible presence of life on other planets. For example, Němečková et al [ 24 ] investigated microbial colonizations of gypsum from different sites from Southern Sicily and Eastern Poland using laboratory‐based Raman micro‐spectrometers and portable Raman spectrometric devices. Authors describe selected zones of microbial colonizations of few types of gypsum from the point of view of the presence of algae and cyanobacteria.…”

Using Raman spectroscopy to detect scytonemin of epiliths and endoliths from marble, serpentinite and gypsum

“…[ 46 ] More achievements of the technique appeared later on photosynthetic and protective pigments of very different microorganisms, including extremophillic ones, as reviewed, for example, by Jehlička et al and Maia et al [ 47,48 ] Raman spectroscopy was suggested as an excellent tool to rapidly prospect, detect and discriminate pigments on rocky outcrops. [ 49,50 ]…”

“…[ 57 ] They are also common photosynthetic pigments connected to the cyanobacterial endolithic colonisations at different sites in eastern Poland as reported recently. [ 50 ]…”

“…[46] More achievements of the technique appeared later on photosynthetic and protective pigments of very different microorganisms, including extremophillic ones, as reviewed, for example, by Jehlička et al and Maia et al [47,48] Raman spectroscopy was suggested as an excellent tool to rapidly prospect, detect and discriminate pigments on rocky outcrops. [49,50] Scytonemin was reported from rocky colonisations of different types many times as detected using Fourier transform (FT)-Raman spectroscopy with 1064-nm excitation. These studies describe colonisations from different cold areas, for instance, [51,52] or from warm desert zones, more commonly using 785 nm [53] but also using FT-Raman spectroscopy with 1064-nm excitation.…”