Coherent anti‐stokes Raman scattering microscopy (CARS) was applied to visualize carotenoids in microalgae and cyanobacteria. Nonlinear light–matter interaction utilized in CARS microscopy inevitably induces a number of competing nonlinear processes, such as multiphoton excitation fluorescence. Microalgae and cyanobacteria being an intrinsically well‐fluorescent object generates a strong two‐photon‐excitation fluorescence (TPEF) signal which should be effectively suppressed during the CARS experiment. Using an energetically balanced duel‐wavelength excitation scheme and spectral purification of detecting signal, the TPEF was completely blocked providing a possibility to probe microalgae and cyanobacteria in a fingerprint region of the CARS spectrum. Microspectroscopy experiments were carried out with three species ‐ cyanobacteria Nostoc Commune, Nostoc sp. and Chlorella sp. Distinct bands obtained in CARS spectra of such species were assigned to carotenoids and were taken as spectral markers in the imaging experiment. CARS imaging known as a chemical selective and label‐free technique allows non‐invasion monitoring of accumulation and movement of chemical compound at the subcellular level. Obtained high‐resolution images of carotenoid distribution in algae and cyanobacteria clearly demonstrate the potential of CARS microscopy for spatially resolved analysis of the natural products stored in the microalgae and cyanobacteria cell. Copyright © 2013 John Wiley & Sons, Ltd.
This paper deals with the study of scytonemin in cyanobacteria applying coherent anti‐Stokes Raman scattering (CARS) microscopy. The chemically specific CARS response from particular chemical compounds in the algae cell is usually weak because of their low concentration and is often overwhelmed by optical emissions from other cellular constituents. This report demonstrates that for scytonemin localized in cyanobacteria Nostoc commune, the vibrational response is sufficient for its reliable identification. Scytonemin is known as a sunscreen sheath enclosing the cells of microalgae against ultraviolet radiation. The effectiveness of CARS microscopy as a mapping technique with the aim to visualize the scytonemin sheath in a live culture such as cyanobacteria N. commune has been revealed.
Abstract:The aim of this study was to induce lipid accumulation in Chlorella cells by creating stressful growth conditions. Chlorella vulgaris CCALA 896 was grown under various batch growth modes in basal and modified BG-11 and Kolkwitz culture broths, using a continuous light regimen of 150 µE/m 2 /s, at 30 °C . In order to perform the experiments, two indoor photobioreactor shapes were used: a cylindrical glass photobioreactor (C G PBR) with a working volume of 350 mL, and a flat glass photobioreactor (F G PBR) with a working volume of 550 mL. Stress-eliciting conditions, such as nitrogen and phosphorous starvation, were imposed in order to induce lipid accumulation. The results demonstrated that more than 56% of the lipids can be accumulated in Chlorella biomass grown under two-phase batch growth conditions. The highest biomass productivity of 0.30 g/L/d was obtained at the highest nominal dilution rate (0.167 day −1 ) during a semi-continuous regimen, using a modified Kolkwitz medium. During the pH-stress cycles, the amount of lipids did not increase significantly and a flocculation of Chlorella cells was noted. OPEN ACCESSEnergies 2014, 7 3841
This paper deals with the accumulation of lipids, carbohydrates and proteins in the biomass of the green algae Chlorella vulgaris that is cultivated in the municipal wastewater of Vilnius City. The growth rate of the culture on different chemical compositions of media was investigated. Dependence of lipid, carbohydrate and protein content on total phosphorus and nitrogen initial concentrations in wastewater and removal of nutrients was investigated. Data showed that the higher amount of total nitrogen is the main factor leading to a higher rate of biomass increase. The study showed that Chlorella vulgaris is capable of very efficient nutrient removal from wastewater (up to 86% of total nitrogen and 87% phosphorus was removed). Data showed that there is strong correlation between the initial concentration of nitrogen, and in some cases phosphorus, in the media and content of proteins and carbohydrates in the biomass. A higher amount of nitrogen in the starting media leads to a higher amount of proteins and a lower amount of carbohydrate in the biomass. There was no correlation found between the initial nitrogen or phosphorus concentration in the media and content of lipids in the biomass.
The desmid flora of the Girutiskis mire complex reserve in Lithuania, a Natura 2000 territory and a potential Ramsar site, was investigated for the first time. Despite being a relatively small area with homogenous ecological conditions and a narrow range of pH-values, some pattern in the distribution of desmid species was observed. The lowest number of species was observed in the highly acidic lakes that were surrounded by sub-shrub bogs, and the highest number in less acidic lakes that were surrounded by trembling bogs. A total of 78 desmid taxa were found of which 16 were first records for Lithuania. Almost half of the taxa were uniquely found at one site, and only 10% were classified as frequent.
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