PHYCOCYANIN

Description

Phycocyanin is a blue dye formed by cyanobacteria, cryptophytes, and rhodophytes. It is an interesting nutraceutical because of its suspected antioxidative properties, and it is also applied for coloring and fluorescence in biochemical assays. Despite these interesting properties, the yearly market value is comparatively low. Currently, phycocyanin is produced in open basin cultures containing the cyanobacterium Arthrospira (Spirulina) platensis. However, productivities are low as the cultures are very sensitive to contaminating organisms. Recent studies addressing chemical modifications have enhanced the potential applications of phycocyanin in the fields of diagnostics and applications in food, nutraceuticals, and biotechnology. Furthermore, optimization programs significantly increased productivity in heterotrophic and acidophilic cultures of the red alga Galdieria sulphuraria which are grown under well-controlled and axenic conditions. This makes G. sulphuraria an attractive alternative for Spirulina. Furthermore, improvement was achieved with regard to downstream processing: the application of two-phase aqueous extraction methods and optimized purification technologies have resulted in higher productivity and improved performance. Table 4 summarizes the main producers of natural b-carotene, astaxanthin, lutein, and phycoerythrin.

Biotechnological Production

In 2008, the presence of a-, b-, c-, d-, and e-carotenes was reported in 76 algae, 5 fungi, and 4 bacteria. Among them, b-carotene is produced by a number of fungi, for example, by Phycomyces, Mucor, and B. trispora, and dry matter contents of 4–5 g /l are achieved.
Blakeslea trispora is a fungal plant pathogen and belongs to the order of Mucorales. The fungus is nonpathogenic and nontoxigenic for humans and animals. This order includes Phycomyces blakesleeanus, Choanephora cucurbitarum, and B. trispora. Two opposite mating types, namely (+) "plus" and (-) "minus" exist of the Phycomycete B. trispora, and both are able to form zygospores. When plus and minus mating types are cultivated on the same mating plate, they form progametangia. Then septation takes place in the progametangia, which results in the formation of gametangia, which fuse to form zygospores. On these spots high levels of b-carotene are formed [188]. When these types are separated, both types produce low levels of carotenoids, albeit the (-) mating type produces slightly more. However, when the two types are cultivated together in a specific ratio, the (-) type starts to produce 10–20 times more b-carotene and lycopene. The reason is that the (+) type produces the sex hormone trisporic acid, which serves as a stimulator of carotenogenesis. The common denominator of the stimulating effect of trisporic acids are the ionone ring and the hydrocarbon side chain.