Microalgae extraction

Mendes, R.L. et al.. Supercritical carbon dioxide extraction of compounds with pharmaceutical importance from microalgae, Inorg. Chim. Acta, 356, 328, 2003. 

Hejazi, M.A. et al.. Selective extraction of carotenoids from the microalga Dunaliella salina with retention of viability, Biotechnol Bioeng., 79, 29, 2002. 

Hejazi, M.A., Kleinegris, D., and Wijffels, R.H., Mechanism of extraction of P-carotene from microalga Dunaliellea salina in two-phase bioreactors, Biotechnol. Bioeng., 88, 593, 2004. 

The microalgae are cultured in bioreactors under solar or artiflcial light in the presence of carbon dioxide and salts. The bioreactors may be closed systems made of polyethylene sleeves rather than open pools. Optimal conditions for pigment production are low to medium light intensity and medium temperatures (20 to 30°C). Pigment extraction is achieved by cell breakage, extraction into water or buffered solution, and centrifugation to separate out the filtrate. The filtrate may then be partly purified and sterilized by microfiltration and spray dried or lyophilized. 

Other kinds of bloassays have been used to detect the presence of specific allelochemical effects (8), effects on N2 fIxatlon (9), the presence of volatile compounds (10) and of Inhibitory substances produced by marine microalgae (11). Putnam and Duke (12) have summarized the extraction techniques and bioassay methods used In allelopathy research. Recent developments In high performance liquid chromatography (HPLC) separation of allelochemlcals from plant extracts dictates the need for bloassays with sensitivity to low concentrations of compounds contained In small volumes of eluent. Einhellig at al. (13) described a bloassay using Lemna minor L. growing In tissue culture cluster dish wells that maximizes sensitivity and minimizes sample requirements. 

Another commercially available product containing naturally occurring marine products is Formulaid , produced by Martek Biosciences as a nutritional supplement for infant formulas. Formulaid contains two fatty acids, arachidonic acid (ARA) and docosahexaenoic acid (DHA), extracted from a variety of marine microalgae. ARA and DHA are the most abundant polyunsaturated fatty acids found in breast milk, and they are the most important fatty acids used in the development of brain gray matter. They are especially desirable for use in infant formulas because they come from nonmeat sources and can be advertised as vegetarian additives to the product. 

The activity of extracts against microalgae has led to the isolation of a large group of simple phenylethyl amides and various indolylethyl amides (e.g., 27, 28). We have obtained some of these compounds also from limnic bacteria, and, although their activity is low, it seems plausible that they play a role in the competition of bacteria with microalgae for free surfaces, perhaps on seaweed or other sessile organisms. 

Photosynthetic microalga Haematococcus pluvicdis) vfikS inoculated at 2.0 kg dry cell rn and cultured in a basal medium (containing yeast extract, acetate, asparagine, and some metals) under illumination by fluorescent lamps. The cell concentrations are shown in Table P4.4. 

Harrison, P.G. and Chan, A.T., 1980. Inhibition of the growth of microalgae and bacteria by extracts of eelgrass, (Zostera marina) leaves. Mar. Biol., 61 21-26. 

MAAs have not been studied as extensively in freshwater as in marine species, but these compounds have been reported in freshwater cyanobacteria, microalgae, invertebrates, and chordates (fish).106 116 130-133 There may be several MAAs unique to freshwater organisms. Aqueous extracts from the cyanobacterium Nostoc commune contain a mixture of UV-absorbing compounds with two distinct chromophores that have maximum absorbance at 312 and 335 nm.134 135 These compounds are comprised of the usual mycosporine cyclohexenone ring structure however, it is... 

A natural SP OKU-40 was extracted from the marine microalga Dinoflag-ellata and was found to inhibit the replication of HIV, RSV, influenza A and B viruses, measles virus, and parainfluenza viruses type 2 (PIV-2). However, it did not inhibit the replication of mumps virus or PIV-3 [98]. The action of negatively charged polysaccharides is not merely one of nonspecific inhibition of the binding of an enveloped virus to receptors. In fact, OKU-40 did not inhibit the binding of HIV or influenza A virus to the cell membrane, but it did inhibit the fusion of the membranes of HIV-infected MOLT-4 cells to those of uninfected cells and the fusion of the influenza A virus envelope to uninfected MDCK cells [99]. 

Herrero, M., Cifuentes, A. and Ibanez, E. 2006. Sub- and Supercritical Fluid Extraction of Functional Ingredients from Different Natural Sources Plants, Food-By-Products, Algae and Microalgae. Food Chem., 98, 136-148. 

With the increasing interest in the food industry for natural sources of antioxidants for their beneficial effects on health, new potential sources have been screened among edible aromatic plants and microalgae. The cc-tocopherol content (a potent antioxidant) in parsley was reported to be 3.45mg/100g of fresh leaves obtained through supercritical fluid extraction (Diego et al., 2004). 

An integrated process for highly purified PUFAs from microalgae has been developed at the University of Almeria (Molina Grima et al., 1996). The process basically employs solvent extraction, phase separation, urea adduction of fatty acids, and chromatographic separation of PUFA rich fraction the process is summarized in Figure 26.1. The same is applicable to recovery of PUFA rich lipid fractions from seaweeds as well. 

Martek (http //www.martekbio.com) and DSM have developed processes to produce oils rich in DHA and ARA. The DHA is extracted from fermented microalgae (Cryptecodiunium cohnii) and the ARA is extracted from soil fungus (Mortierelle alpina). In the DHA production process, the microalgae are grown in fermentors (80,000 to 260,000 liters scale). The cellmass is then... 

The principles of sonochemistry can also be applied to disrupt different species of oil-bearing microalgae cells. Detailed experimental results are necessary to support the cost-effectiveness and industrial scale applicability of ultrasound for microbial lipid extraction, and subsequent biodiesel production in comparison to conventional methods (Mata et al., 2010). 

Herrero M. Cifiientes A. Ibanez E. 2006. Sub- and supercritical fluid extraction of functional ingredients from different natural sourees Plants, food-by-products, algae and microalgae A review. Food Chem. 98 136-148. 

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