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

Here, we present Raman spectra showing the presence and distribution of scytonemin and carotenoids in epilithic and endolithic colonisations from temperate locations in Central Europe and Sicily. In the Bohemian Massif, marble and serpentinitic cyanobacterial epiliths dominated by cyanobacteria Scytonema, Stigonema, Hassallia, Gloeocapsopsis and Gloeocapsa were investigated using light microscopy and Raman spectroscopy. Scytonemin was a common dark pigment, accompanied by carotenoids and gloeocapsin on the marbles from Opolenec and on serpentinites from Holubov (South Bohemia). Raman spectra from other sites originated from endolithic colonisations of gypsum. They were located in the Carpathian foredeep (Badenian, Silesian unit, eastern Poland) and in Messinian complexes in the Mediterranean area (Sicily). Similarly to the previous localities, almost ubiquitous occurrence of scytonemin confirmed the presence of cyanobacterial colonisations. Obtained findings are important from the spectroscopic point of view. Additionally, comparing results from several sites confirmed the common occurrence of scytonemin in both endoliths and epiliths from areas that cannot be considered climatically extreme, although they experience rapid fluctuations in temperature, humidity and UV irradiation on the exposed rocky substrates.

Automated summary

In this study, Raman spectra were used to investigate the presence and distribution of scytonemin and carotenoids in epilithic and endolithic colonisations in temperate areas of Central Europe and Sicily. The results showed that scytonemin was commonly found in cyanobacterial epiliths dominated by cyanobacteria such as Scytonema, Stigonema, Hassallia, Gloeocapsopsis and Gloeocapsa. Additionally, scytonemin was also detected in endolithic colonisations in gypsum. The findings suggest that scytonemin is present in both endoliths and epiliths from areas that are not considered climatically extreme.