Melting glacier surfaces are increasingly affected by blooms of psychrophilic microalgae, which darken the ice and lower its albedo, accelerating melting. These microalgae contain distinct vacuoles filled with brownish pigments that were earlier described as the unusual plant phenol purpurogallin. Recently, we discovered so far unreported, large amounts of iron dissolved in aqueous extracts of the glacier ice algae Ancylonema alaskanum. Since the vacuole content was very dark but the chromatographically isolated, aforementioned phenol was only yellowish, a putative complexation of iron with purpurogallin was assumed to be the reason. Application of several protocols, including Raman microscopy on both living cells and extracts, provided strong evidence that this microalga sequesters iron and forms organic metal complexes. Consequently, substantial amounts of so far uncharacterised Fe-complexes of purpurogallin are inferred to be present in Ancylonema, and that putative polymerisation of this compound impeded an earlier analytical discovery. This finding holds significant ecological implications for cold regions. The pigmentation not only enhances the tolerance of glacier ice algae to excessive UV and visible radiation but also influences our current understanding of the biochemical iron cycle in cryosphere-dominated polar and alpine regions. Further downstream consequences of this biological iron source remain to be elucidated.

• Keywords
• Raman microscopy, cryoflora, glaciers, polyphenols, secondary pigmentation,
• MeSH
• Phenols * metabolism   chemistry   MeSH
• Ice Cover * microbiology   MeSH
• Microalgae * radiation effects   chemistry   metabolism   MeSH
• Light MeSH
• Ultraviolet Rays * MeSH
• Iron * metabolism   chemistry   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Phenols * MeSH
• Iron * MeSH

Barium and strontium are often used as proxies of marine productivity in palaeoceanographic reconstructions of global climate. However, long-searched biological drivers for such correlations remain unknown. Here, we report that taxa within one of the most abundant groups of marine planktonic protists, diplonemids (Euglenozoa), are potent accumulators of intracellular barite (BaSO4), celestite (SrSO4), and strontiobarite (Ba,Sr)SO4. In culture, Namystinia karyoxenos accumulates Ba2+ and Sr2+ 42,000 and 10,000 times higher than the surrounding medium, forming barite and celestite representing 90% of the dry weight, the greatest concentration in biomass known to date. As heterotrophs, diplonemids are not restricted to the photic zone, and they are widespread in the oceans in astonishing abundance and diversity, as their distribution correlates with environmental particulate barite and celestite, prevailing in the mesopelagic zone. We found diplonemid predators, the filter-feeding zooplankton that produces fecal pellets containing the undigested celestite from diplonemids, facilitating its deposition on the seafloor. To the best of our knowledge, evidence for diplonemid biomineralization presents the strongest explanation for the occurrence of particulate barite and celestite in the marine environment. Both structures of the crystals and their variable chemical compositions found in diplonemids fit the properties of environmentally sampled particulate barite and celestite. Finally, we propose that diplonemids, which emerged during the Neoproterozoic era, qualify as impactful players in Ba2+/Sr2+ cycling in the ocean that has possibly contributed to sedimentary rock formation over long geological periods. IMPORTANCE We have identified that diplonemids, an abundant group of marine planktonic protists, accumulate conspicuous amounts of Sr2+ and Ba2+ in the form of intracellular barite and celestite crystals, in concentrations that greatly exceed those of the most efficient Ba/Sr-accumulating organisms known to date. We propose that diplonemids are potential players in Ba2+/Sr2+ cycling in the ocean and have possibly contributed to sedimentary rock formation over long geological periods. These organisms emerged during the Neoproterozoic era (590 to 900 million years ago), prior to known coccolithophore carbonate biomineralization (~200 million years ago). Based on reported data, the distribution of diplonemids in the oceans is correlated with the occurrence of particulate barite and celestite. Finally, diplonemids may provide new insights into the long-questioned biogenic origin of particulate barite and celestite and bring more understanding of the observed spatial-temporal correlation of the minerals with marine productivity used in reconstructions of past global climate.

• Keywords
• Euglenozoa, barite, biocrystallization, biogeochemical cycles, celestite,
• MeSH
• Barium MeSH
• Minerals MeSH
• Oceans and Seas MeSH
• Plankton MeSH
• Barium Sulfate * MeSH
• Strontium * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Oceans and Seas MeSH
• Names of Substances
• Barium MeSH
• Minerals MeSH
• Barium Sulfate * MeSH
• Strontium * MeSH

Oleaginous filamentous fungi can accumulate large amount of cellular lipids and biopolymers and pigments and potentially serve as a major source of biochemicals for food, feed, chemical, pharmaceutical, and transport industries. We assessed suitability of Fourier transform (FT) Raman spectroscopy for screening and process monitoring of filamentous fungi in biotechnology. Six Mucoromycota strains were cultivated in microbioreactors under six growth conditions (three phosphate concentrations in the presence and absence of calcium). FT-Raman and FT-infrared (FTIR) spectroscopic data was assessed in respect to reference analyses of lipids, phosphorus, and carotenoids by using principal component analysis (PCA), multiblock or consensus PCA, partial least square regression (PLSR), and analysis of spectral variation due to different design factors by an ANOVA model. All main chemical biomass constituents were detected by FT-Raman spectroscopy, including lipids, proteins, cell wall carbohydrates, and polyphosphates, and carotenoids. FT-Raman spectra clearly show the effect of growth conditions on fungal biomass. PLSR models with high coefficients of determination (0.83-0.94) and low error (approximately 8%) for quantitative determination of total lipids, phosphates, and carotenoids were established. FT-Raman spectroscopy showed great potential for chemical analysis of biomass of oleaginous filamentous fungi. The study demonstrates that FT-Raman and FTIR spectroscopies provide complementary information on main fungal biomass constituents.

• Keywords
• biodiesel, biopolymers, carotenoids, chitin, chitosan, fatty acids, fermentation, fungi, oleaginous microorganisms, pigments,
• MeSH
• Principal Component Analysis MeSH
• Pigments, Biological analysis   MeSH
• Biomass MeSH
• Biotechnology MeSH
• Chromatography, Gas MeSH
• Phosphorus analysis   metabolism   MeSH
• Fourier Analysis MeSH
• Fungi chemistry   growth & development   MeSH
• Carotenoids analysis   MeSH
• Lipids analysis   MeSH
• Magnetic Resonance Spectroscopy MeSH
• Spectrum Analysis, Raman methods   MeSH
• Spectrophotometry, Ultraviolet MeSH
• Spectroscopy, Fourier Transform Infrared MeSH
• Calcium metabolism   MeSH
• Chromatography, High Pressure Liquid MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Pigments, Biological MeSH
• Phosphorus MeSH
• Carotenoids MeSH
• Lipids MeSH
• Calcium MeSH

Photosynthetic energy conversion and the resulting photoautotrophic growth of green algae can only occur in daylight, but DNA replication, nuclear and cellular divisions occur often during the night. With such a light/dark regime, an algal culture becomes synchronized. In this study, using synchronized cultures of the green alga Desmodesmus quadricauda, the dynamics of starch, lipid, polyphosphate, and guanine pools were investigated during the cell cycle by two independent methodologies; conventional biochemical analyzes of cell suspensions and confocal Raman microscopy of single algal cells. Raman microscopy reports not only on mean concentrations, but also on the distribution of pools within cells. This is more sensitive in detecting lipids than biochemical analysis, but both methods-as well as conventional fluorescence microscopy-were comparable in detecting polyphosphates. Discrepancies in the detection of starch by Raman microscopy are discussed. The power of Raman microscopy was proven to be particularly valuable in the detection of guanine, which was traceable by its unique vibrational signature. Guanine microcrystals occurred specifically at around the time of DNA replication and prior to nuclear division. Interestingly, guanine crystals co-localized with polyphosphates in the vicinity of nuclei around the time of nuclear division.

• Keywords
• Desmodesmus quadricauda, cell cycle, confocal Raman microscopy, guanine, lipids, microalgae, polyphosphate, starch,
• MeSH
• Cell Wall chemistry   MeSH
• Cell Cycle * MeSH
• Time Factors MeSH
• Chlorophyta cytology   growth & development   MeSH
• Guanine analysis   MeSH
• Lipid Droplets metabolism   MeSH
• Lipids analysis   MeSH
• Microscopy * MeSH
• Polyphosphates analysis   MeSH
• Spectrum Analysis, Raman * MeSH
• Starch analysis   MeSH
• Cell Size MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Guanine MeSH
• Lipids MeSH
• Polyphosphates MeSH
• Starch MeSH

Nitrogen (N) is an essential macronutrient for microalgae, influencing their productivity, composition, and growth dynamics. Despite the dramatic consequences of N starvation, many free-living and endosymbiotic microalgae thrive in N-poor and N-fluctuating environments, giving rise to questions about the existence and nature of their long-term N reserves. Our understanding of these processes requires a unequivocal identification of the N reserves in microalgal cells as well as their turnover kinetics and subcellular localization. Herein, we identified crystalline guanine as the enigmatic large-capacity and rapid-turnover N reserve of microalgae. The identification was unambiguously supported by confocal Raman, fluorescence, and analytical transmission electron microscopies as well as stable isotope labeling. We discovered that the storing capacity for crystalline guanine by the marine dinoflagellate Amphidiniumcarterae was sufficient to support N requirements for several new generations. We determined that N reserves were rapidly accumulated from guanine available in the environment as well as biosynthesized from various N-containing nutrients. Storage of exogenic N in the form of crystalline guanine was found broadly distributed across taxonomically distant groups of microalgae from diverse habitats, from freshwater and marine free-living forms to endosymbiotic microalgae of reef-building corals (Acropora millepora, Euphyllia paraancora). We propose that crystalline guanine is the elusive N depot that mitigates the negative consequences of episodic N shortage. Guanine (C5H5N5O) may act similarly to cyanophycin (C10H19N5O5) granules in cyanobacteria. Considering the phytoplankton nitrogen pool size and dynamics, guanine is proposed to be an important storage form participating in the global N cycle.

• Keywords
• coral, guanine, nitrogen cycle, nutrient storage, phytoplankton,
• MeSH
• Dinoflagellida chemistry   metabolism   MeSH
• Nitrogen metabolism   MeSH
• Ecosystem MeSH
• Guanine chemistry   metabolism   MeSH
• Kinetics MeSH
• Anthozoa MeSH
• Crystallization MeSH
• Microalgae chemistry   metabolism   MeSH
• Nonlinear Optical Microscopy methods   MeSH
• Symbiosis MeSH
• Microscopy, Electron, Transmission MeSH
• Tropical Climate MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Video-Audio Media MeSH
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Arctic Regions MeSH
• Names of Substances
• Nitrogen MeSH
• Guanine MeSH