Algae are aquatic organisms which obtain energy via photosynthesis. Algae capture CO 2 and transform it into organic carbon. Algae comprises of two major groups – macroalgae and microalgae. Microalgae are a diverse group of unicellular organisms with more than 30,000 known species. Although microalgae, in their strictest sense, are eukaryotes, this chapter will also consider cyanobacteria (blue-green algae), which are prokaryotes with photosynthetic capacity. In spite of the great number of species that belong to this group of living forms, only a handful are currently of commercial signifi cance (Bruton et al. 2009 ).
