The cyanobacterium Spirulina is well recognized as a
potential food supplement for humans because of its high levels of protein (65-70% of dry
weight), vitamins and minerals. In addition to its high protein level, Spirulina cells also
contain significant amounts of phycocyanin, an antioxidant that is used as an ingredient in
various products developed by cosmetic and pharmaceutical industries. Spirulina cells also
produce sulfolipids that have been reported to exert inhibitory effects on the Herpes simplex
type I virus. Moreover, Spirulina is able to synthesize polyunsaturated fatty acids such as
glycerolipid gamma-linolenic acid (GLA; C18:3(Delta 9,12,6)), which comprise 30% of the total
fatty acids or 1-1.5% of the dry weight under optimal growth conditions. GLA, the end product of
the desaturation process in Spirulina, is a precursor for prostaglandin biosynthesis;
prostaglandins are involved in a variety of processes related to human health and disease.
Spirulina has advantages over other GLA-producing plants, such as evening primrose and borage, in
terms of its short generation time and its compatibility with mass cultivation procedures.
However, the GLA levels in Spirulina cells need to be increased to 3% of the dry weight in order
to be cost-effective for industrial scale production. Therefore, extensive studies aimed at
enhancing the GLA content of these cyanobacterial cells have been carried out during the past
decade. As part of these extensive studies, molecular biological approaches have been used to
study the gene regulation of the desaturation process in Spirulina in order to find approaches
that would lead to increased GLA production. The desaturation process in S. platensis occurs
through the catalytic activity of three enzymes, the Delta(9), Delta(12) and Delta(6) desaturases
encoded by the desC, desA and desD genes, respectively. According to our previous study, the
cellular GLA level is increased by approximately 30% at low temperature (22 degrees C) compared
with its level in cells grown at the optimal growth temperature (35 degrees C). Thus, the
temperature stress response of Spirulina has been explored using various techniques, including
proteomics. The importance of Spirulina has led to the sequencing of its genome, laying the
foundation for various additional studies. However, despite the advances in heterologous
expression systems, the primary challenge for molecular studies is the lack of a stable
transformation system. Details on the aspects mentioned here will be discussed in the chapter
highlighted Spirulina: Biotechnology, Biochemistry, Molecular Biology and Applications.