The below mentioned article provides notes on algal culture.
Algae are a diverse group of plant like organisms. Like plants, most algae use photosynthesis to convert carbon dioxide, water and some elements into biomass, secondary metabolites and oxygen.
They differ from plants because algae don’t have true roots, leaves and other structures typical for plants. The diversity in algae is enormous. Seaweeds (macroalgae) have the most complex multicellular anatomy of all algae. Some even have differentiated tissues and organs that resemble those we find in plants.
The similarities, however, are analogous, not homologous. Giant seaweeds known as kelps can be found in deeper waters. The stipes of these brown algae may be as long as 100 meter. Microalgae are much smaller than these (± 1 um) and can be found in fresh-and seawater.
The great kelp beds of temperate coastal waters provide habitat and food for a variety of organism. The kelps, brown algae, are prodigiously productive. This alga: Macrocystis grows to a length of more than 60 m in a single season, the fastest linear growth of any organism.
Algal culture is chiefly used to generate biomass from which cells and metabolites can be isolated. Culturing often takes place in large ponds or raceways. Cultured algal cells also are used to minimise the production of high cost of rare compounds. This type of culturing usually takes place in a fermenter or a bioreactor rather than in ponds.
Culture conditions are highly controlled and the products undergo significant downstream processing of products collection, purification and packaging. Currently, microalgae are the main organisms used in culture, although macroalgae yield valuable agars and agarose that are used in research and diagnostic labs.
Cell culture technology may be able to contribute to agar production methods, and the scarcity of agar – producing algae. Cell culture technology may be able to contribute to agar production. Specialty chemicals are produced from microalgal cultures.
For example, a particular strain of Cholella has been developed that produces 30% more proline than other strains produce. The proline can be readily extracted from the culture for commercial use. A variety of hydrocarbons, polysaccharide and other important compounds also can be produced.
Gene transfer from other organisms can yield new algal products; for example, after genes are transferred from bacteria, the algae Chlamydomonas can produce the rare amino acid octopamine. Although algal cell culture is a high cost operation, the products that are isolated can be very profitable.
For example, amino acid fetch $5 to $100/kilogram; food colouring phycobiliprotiens. Other industrial compounds, such as dihydroxyacetone, gluconic acid, hydrogen and acetic acid are produced by immobilised microalgal cells. One algal culture in a large fermenter potentially can generate thousands of dollars of specialty chemicals every month.
The diversity of microalgae is huge. Monodus produces unsaturated fatty acids and has a size of approximately 3.5 um. Algae are extremely important ecologically, accounting for about half the photosynthetic production of organic material on a global scale. As freshwater and marine phytoplankton and intertidal seaweeds, algae are the basis of aquatic food webs, supporting an enormous abundance and diversity of animals.
Biotechnological use of microalgae is very interesting: solar radiation is used as energy source and inorganic CO2 as carbon source by autotrophic microorganisms. Both substrates are abundant and cheap. Also,micro-algae produce high-value compounds that cannot be obtained otherwise.
Examples are photosynthetic pigments such as carotenoids that are commercially used as pro-vitamin A, antioxidant and colorant agent. The aim of this project is the production and extraction of lipophilic vitamins from marine micro-algae. β-Carotene (pro-vitamin A) produced by Dunaliella salina is used as a model system.