Unicellular microalgae

Diatoms are unicellular, photosynthetic microalgae that are abundant in the world s oceans and fresh waters. It is estimated that several tens of thousands of different species exist sizes typically range from ca 5 to 400 pm, and most contain an outer wall of amorphous hydrated silica. These outer walls (named frustules ) are intricately shaped and fenestrated in species-specific (genetically inherited) patterns5,6. The intricacy of these structures in many cases exceeds our present capability for nanoscale structural control. In this respect, the diatoms resemble another group of armored unicellular microalgae, the coccolithophorids, that produce intricately structured shells of calcium carbonate. The silica wall of each diatom is formed in sections by polycondensation of silicic acid or as-yet unidentified derivatives (see below) within a membrane-enclosed silica deposition vesicle 1,7,8. In this vesicle, the silica is coated with specific proteins that act like a coat of varnish to protect the silica from dissolution (see below). The silica is then extruded through the cell membrane and cell wall (lipid- and polysaccharide-based boundary layers, respectively) to the periphery of the cell. 

M., Vigara, J., and Leon, R. (2013) Efficiency of different heterologous promoters in the unicellular microalga Chlamydomonas reinhardtii. Biotechnol. Progr., 29 (2), 319-328. 

Baroukh C, Munoz-Tamayo R, Bernard O, SteyerJ-P Mathematical modeling of unicellular microalgae and cyanobacteria metabohsm for biofael production. Cun Opin Biotechnol 33 198-205, 2015a. 

Baroukh C, Munoz-Tamayo R, Steyer J-P, Bernard O A state of the art of metabohc networks of unicellular microalgae and cyanobacteria for biofuel production, Metab Eng 30 49-60, 2015b. 

Similar to higher plants, unicellular microalgae (microphytes) are able to produce L-ascorbic acid from D-glucose via L-galactose. In this pathway the direct... 

Figure 9.2 The characteristic pattern of growth shown by a unicellular microalga in a culture of limited volume (1) lag phase, (2) exponential phase, (3) phase of declining growth, (4) stationary phase, and (5) death phase. (Adapted from Fogg, copyright 1965, by the Board of Regents of the University of Wisconsin System. Reprinted by permission of The University of Wisconsin Press.)...

The size of the glass beads is important. The optimal size for bacteria and spores is 0.1 mm it is 0.5 mm for yeast, mycelia, microalgae, and unicellular animal cells such as leucocytes or tissue culture cells. The speed of disruption... 

In spite of the fact that both Chlamydomonas reinhardtii and Dunaliella bioculata arc wall-less, the first microalga accumulates Tc with a concentration factor of 90, whereas the second one concentrates Tc with a factor of only 0.3. On the other hand, the cell wall appears not to be a barrier to the penetration of Tc inside algal cells, because the unicellular alga Acetabularia, which possesses a thick ceil wall, strongly accumulates Tc up to a concentration factor of 400 [88]. 

Chlorella is a freshwater, unicellular green microalga that is widely used as a food supplement in Japan and around the world. Mass commercial cultivation of Chlorella for use as a health food supplement has taken place for over 35 years, with a more recent application in mariculture feed (Iwamoto, 2004). Many strains of Chlorella can be grown heterotrophically, allowing for production of a high-quality powder without contamination. Chlorella supplements are taken in the form of tablets, capsules, liquid, or as food additives. Claims for health benefits of Chlorella include improved immune function and improved control of hypertension, fibromyalgia, and ulcerative colitis (Halperin et al, 2003). 

Microalgae represent a diverse group of eukaryotic photosynthetic microorganisms that are either unicellular or multicellular in form. It is estimated that there are over 50 000 species present in nature. They can survive under a wide range of environmental conditions, from water to land and even in snow and desert soils. ... 

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