The exploration of organic biosignatures on extraterrestrial bodies is an ambitious endeavor, with future missions employing spectroscopic techniques to search for signs of microbial life. It is both timely and critical to develop an understanding of Raman spectral biosignatures representative of microbial life in order to accurately interpret spectral data from extraterrestrial bodies. We propose an advancement in single cell microbial Raman analysis using multivariate statistical approaches.
This study analyzed microbes from Antarctica and Greenland, cataloguing their spectral profiles using UV/Vis, Fourier-Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy. Principal component analysis (PCA) of the Raman signatures of cellular components was used to construct a targeted spectra integration (TSI) biplot to visually discern how different microbial spectra vary with respect to cellular features (e.g. lipids, proteins, carbohydrates and pigments). Supervised and unsupervised statistical analyses were used to support the TSI biplot analysis. This approach allowed for a unique, multi-technique analysis of spectral information from Polar microbial isolates that identified trends based on biosignatures.