settingsOrder Article Reprints This is an early access version, the complete PDF, HTML, and XML versions will be available soon. Open AccessArticle Near-Infrared Metabolomic Fingerprinting Study of Lichen Thalli and Phycobionts in Culture: Aquaphotomics of Trebouxia lynnae Dehydration by Irene Bruñas Gómez 1,Monica Casale 2,Eva Barreno 3ORCID andMyriam Catalá 1,*ORCID 1 Department of Biology and Geology, School of Experimental Science & Technology, Rey Juan Carlos University, Av. Tulipán s/n, 28933 Madrid, Spain 2 DIFAR Department of Pharmacy, University of Genova, 16148 Genova, Italy 3 Instituto Cavanilles de Biodiversidad y Biología Evolutiva (ICBiBE), Departamento de Botánica y Geología, Universitat de València, C/Dr. Moliner, 50, 46100 Valencia, Spain * Author to whom correspondence should be addressed. Microorganisms 2022, 10(12), 2444; https://doi.org/10.3390/microorganisms10122444 (registering DOI) Received: 8 October 2022 / Revised: 3 December 2022 / Accepted: 5 December 2022 / Published: 10 December 2022 (This article belongs to the Special Issue Feature Collection in Environmental Microbiology Section 2021-2022) Download Review Reports Versions Notes Abstract Near-infrared spectroscopy (NIRS) is an accurate, fast and safe technique whose full potential remains to be exploited. Lichens are a paradigm of symbiotic association, with extraordinary properties, such as abiotic stress tolerance and adaptation to anhydrobiosis, but subjacent mechanisms await elucidation. Our aim is characterizing the metabolomic NIRS fingerprints of Ramalina farinacea and Lobarina scrobiculata thalli, and of the cultured phycobionts Trebouxia lynnae and Trebouxia jamesii. Thalli collected in an air-dry state and fresh cultivated phycobionts were directly used for spectra acquisition in reflectance mode. Thalli water peaks were associated to the solvation shell (1354 nm) and sugar–water interactions (1438 nm). While northern–southern orientation related with two hydrogen bonded (S2) water, the site was related to one hydrogen bonded (S1). Water, lipids (saturated and unsaturated), and polyols/glucides contributed to the profiles of lichen thalli and microalgae. R. farinacea¸ with higher desiccation tolerance, shows higher S2 water than L. scrobiculata. In contrast, fresh phycobionts are dominated by free water. Whereas T. jamesii shows higher solvation water content, T. lynnae possesses more unsaturated lipids. Aquaphotomics demonstrates the involvement of strongly hydrogen bonded water conformations, polyols/glucides, and unsaturated/saturated fatty acids in the dehydration process, and supports a “rubbery” state allowing enzymatic activity during anhydrobiosis. Keywords: Anhydrobiosis; desiccation; phycobiont; Ramalina farinacea; Lobarina scrobiculata; Trebouxia lynnae; Trebouxia jamesii; aquaphotomics; metabolomic profile.