Microalgae Lipids

The synthesis of microbial fat by bacteria is often ignored because the average fat concentration in dry biomass does not exceed 10%. However, there are strains of Arthrobacter sp., Mycobacterium, and Corynebacterium that are able to accumulate from 30 to 80% lipids in dry matter. Unfortunately, there are other problems related to low growth rates and yields of bacteria, lipid extraction, and the possible allergeiucity and toxicity of the resulting lipids. Microalgae (e.g., Botryococcus braunii and Chlorella pyrenoidosa) serve as attractive sources of PEFA. Dry biomass fat can amount to as much as 85% (Kay, 1991). Moreover, microalgae are a very... 

The red microalga Porphyridium aerugineum is a source of blue color. This species is different from other red microalgae in that it lacks red phycoerythrin and its phycocyanin is C-phycocyanin rather than the R-phycocyanin that accompanies phycoerythrin found in many red algae and in other Porphyridium species. However, the biochemicals produced by P. aerugineum are similar to those of other red microalgae, e.g., sulfated polysaccharides, carotenoids, and lipids. An alternative source of C-phycocyanin is Spirulina platensis. ... 

SCFE of lipids from two freeze-dried microalgae species were studied (Po-lak et al., 1989). 

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. 

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. 

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). 

Allard B., Rager M.-N., and Templier J. (2002) Occurrence of high molecular weight lipids (C ) in the trilaminar outer cell walls of some freshwater microalgae. A reappraisal of algaenan structure. Org. Geochem. 33, 789-801. 

We have studied CO2 fixation of the exhaust gas from thermal power stations by microalgal photosynthesis. In order to utilize the resulting large quantities of biomass for fuel, compost, feed and other useful chemical substances, we have screened microalgae which produce lipids or hydrocarbons. In this study, we report the isolation and characterization of a green alga tolerant of the concentration of 10%CO2 at30t . 

It is possible to obtain lipids from microalgae by conventional solvent extraction. However, extraction with supercritical (SC) CO, is emerging as a potential alternative to obtain lipids from natural sources (13-19). 

The objective of this study was to determine the lipid extraction yields from two species of microalgae by SC CO2, and to investigate the factors that influence these yields. 

We studied the extraction of lipids from algae (Isochrysis galbana Parke) to verify the possibility to enrich EPA, DHA or other omega-3 fatty acids for healthy products or pharmaceutical application (35). We found that the SFs allow the extraction of lipids from microalgae with interesting fatty acid composition and good extraction yield in comparison with traditional solvents. 

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