Differential Membrane Lipid Profiles and Vibrational Spectra of Three Edaphic Algae and One Cyanobacterium

Abstract

The membrane glycerolipids of four phototrophs that were isolated from an edaphic assemblage were determined by UPLC–MS after cultivation in a laboratory growth chamber. Identification was carried out by 18S and 16S rDNA sequencing. The algal species were Klebsormidium flaccidum (Charophyta), Oocystis sp. (Chlorophyta), and Haslea spicula (Bacillariophyta), and the cyanobacterium was Microcoleus vaginatus (Cyanobacteria). The glycerolipid profile of Oocystis sp. was dominated by monogalactosyldiacylglycerol (MGDG) species, with MGDG(18:3/16:4) accounting for 68.6%, whereas MGDG(18:3/16:3) was the most abundant glycerolipid in K. flaccidum (50.1%). A ratio of digalactosyldiacylglycerol (DGDG) species to MGDG species (DGDG/MGDG) was shown to be higher in K. flaccidum (0.26) than in Oocystis sp. (0.14). This ratio increased under high light (HL) as compared to low light (LL) in all the organisms, with its highest value being shown in cyanobacterium (0.38–0.58, LL−HL). High contents of eicosapentaenoic acid (EPA, C20:5) and hexadecenoic acid were observed in the glycerolipids of H. spicula. Similar Fourier transform infrared (FTIR) and Raman spectra were found for K. flaccidum and Oocystis sp. Specific bands at 1629.06 and 1582.78 cm−1 were shown by M. vaginatus in the Raman spectra. Conversely, specific bands in the FTIR spectrum were observed for H. spicula at 1143 and 1744 cm−1. The results of this study point out differences in the membrane lipid composition between species, which likely reflects their different morphology and evolutionary patterns.

The outstanding capacity of Prasiola antarctica to thrive in contrasting harsh environments relies on the constitutive protection of thylakoids and on morphological plasticity

“…Very likely, the appearance of OGLs was one of the adaptations that simultaneously provided advantages against environmental constraints such as desiccation and freezing during land colonisation by plants (Gasulla et al., 2019). Unfortunately, very few studies have addressed the composition and stress responses of OGLs (reviewed in Gasulla et al., 2019) and, to the best of our knowledge, just a few works are available for Chlorophyte species, so far (Benson et al., 1958; Gasulla et al., 2016; Mendiola‐Morgenthaler et al., 1985; Montero et al., 2021; Vieler et al., 2007).…”

Acquisition of Desiccation Tolerance Unveiled: Polar Lipid Profiles of Streptophyte Algae Offer Insights

“…DGD supposedly represents the ancestral route of OGL biosynthesis and results in the constitutive accumulation of OGLs, while SFR2 appeared more recently at some point in streptophyte evolution (Gasulla et al, 2019), providing a mechanism for faster membrane remodelling in response to environmental fluctuations (Moellering & Benning, 2011). Interestingly, the very scarce literature available regarding galactolipid composition and its changes under stress in green algae indicates a higher DGDG/MGDG ratio in desiccation‐tolerant than in desiccation‐sensitive species and an inducible further rise in response to stress, i.e., high irradiance, desiccation or freezing (Montero et al, 2021).…”