Three-dimensional ultrastructure and hyperspectral imaging of metabolite accumulation and dynamics in Haematococcus and Chlorella

Theoretical and experimental study on the radiative properties of Parachlorella kessleri: considering the effect of internal microstructure

A microalgal cell model with multiple organelles considering both the irregular overall shape and internal microstructure was proposed. The radiative properties of Parachlorella kessleri during the normal phase, starch-rich phase, and lipid-rich phase were calculated by the discrete dipole approximation method in the visible wavelengths. The accuracy of the model is verified with experimental measurements. The results showed that the theoretical calculation of the established microalgal cell model is more accurate than those of the equal volume spheres, such as the homogeneous sphere and the coated sphere, with the errors of the scattering cross-section reduced by more than 10.7%. The calculated scattering phase function of the multi-component model is basically in good agreement with the experimental results. Compared to the normal growth phase, the lipid enrichment during the lipid-rich phase leads to a sharp increase in the scattering cross-section by three to four times, while the absorption cross-section remains stable. Remarkably, in the starch-rich phase, the abundant production of starch results in a reduction of two to three times in the absorption cross-section compared to the normal growth phase, while the scattering cross-section varies little. The results can provide basic data and theoretical support for the design and optimization of photobioreactors.

Astaxanthin and other Nutrients from Haematococcus pluvialis-Multifunctional Applications

Bioactive compounds of natural origin are gaining increasing popularity. High biological activity and bioavailability, beneficial effects on health and safety of use are some of their most desirable features. Low production and processing costs render them even more attractive. Microorganisms have been used in the food, medicinal, cosmetic and energy industries for years. Among them, microalgae have proved to be an invaluable source of beneficial compounds. Haematococcus pluvialis is known as the richest source of natural carotenoid called astaxanthin. In this paper, we focus on the cultivation methods of this green microalga, its chemical composition, extraction of astaxanthin and analysis of its antioxidant, anti-inflammatory, anti-diabetic and anticancer activities. H. pluvialis, as well as astaxanthin can be used not only for the treatment of human and animal diseases, but also as a valuable component of diet and feed.

The Extremophile Endolithella mcmurdoensis gen. et sp. nov. (Trebouxiophyceae, Chlorellaceae), A New Chlorella-like Endolithic Alga From Antarctica

The McMurdo Dry Valleys constitute the largest ice-free region of Antarctica and one of the most extreme deserts on Earth. Despite the low temperatures, dry and poor soils and katabatic winds, some microbes are able to take advantage of endolithic microenvironments, inhabiting the pore spaces of soil and constituting photosynthesis-based communities. We isolated a green microalga, Endolithella mcmurdoensis gen. et sp. nov, from an endolithic sandstone sample collected in the McMurdo Dry Valleys (Victoria Land, East Antarctica) during the K020 expedition, in January 2013. The single non-axenic isolate (E. mcmurdoensis LEGE Z-009) exhibits cup-shaped chloroplasts, electron-dense bodies, and polyphosphate granules but our analysis did not reveal any diagnostic morphological characters. On the basis of phylogenetic analysis of the 18S rRNA (SSU) gene, the isolate was found to represent a new genus within the family Chlorellaceae.