Biomedical Engineering Reference
In-Depth Information
10.2.4.2 Stable Isotope Biochemicals
Microalgae are also well suited to produce isotopically labeled compounds due to
their ability to incorporate stable isotopes from inexpensive inorganic molecules
into high-value isotopic organic chemicals. The ability to cultivate phototropic algae
under strictly controlled conditions enables the easy incorporation of stable isotopes
from inorganic carbon, hydrogen, and nitrogen sources (Pulz and Gross, 2004;
Spolaore et al., 2006; Milledge, 2011). These stable isotopic compounds are used to
facilitate the structural determination (at atomic level) of proteins, carbohydrates,
and nucleic acids. In addition to metabolic studies (Spolaore et al., 2006), they can
also be employed for clinical purposes such as gastrointestinal or breath diagnosis
tests (Radmer, 1996; Pulz and Gross, 2004). Table 10.10 indicates some of the isoto-
pically labeled microalgal products.
The market value of these compounds is estimated at US$13 million per year.
A major distributor of such isotopic compounds is Spectra Stable Isotopes (Andover,
MA; acquired by Cambridge Isotope Laboratories [CIL] in 2008) (Spolaore
et al., 2006).
10.2.4.3 Human Nutrition
The consumption of microalgae is restricted to very few species, for example Spirulina ,
Chlorella, and Dunaliella (Jensen, 1993; Pulz and Gross, 2004). The market value
of microalgal products (health foods) is estimated at US$20-25 million and it is by
far the largest commercial application of microalgae (Metting, 1996). Spirulina and
Chlorella are currently dominating the microalgal market. Spirulina is a source of
protein that is comparable to meat and dairy products. Spirulina also contains high
amounts of vitamin A and B12 (Metting, 1996).
Microalgal products to be used for human nutrition are usually sold in the form of
tablets or powders (Metting, 1996; Radmer, 1996; Pulz and Gross, 2004). The pack-
aged food industry, valued at US$2 trillion, is on the hunt for sustainable and natu-
ral sources of fiber and healthy fats as ingredients for nutritionally high-value and
-quality foods (Singh et al., 1996). Microalgal foods pioneer Solazyme-Roquette has
created “high-lipid algal flour” (Daniells, 2011), intended for use as a main ingredi-
ent alternative to make healthier processed foods such as chocolate milk (4.5% algal
flour), frozen desserts, and even low-calorie salad dressings.
TABLE 10.10
Prices of Different Isotopically Labeled Products
Product Name
Price (US$ g −1 )
Ref.
13 C 6 -d-glucose
140
Fernández et al., 2005
13 C-Mixed free fatty acids
200
Spolaore et al., 2006
13 C-Spirulina
250
Fernández et al., 2005
15 N-Alanine
260
Spolaore et al., 2006
2 H 7 , 13 C, 15 N 4 -Arginine
dATP-CN
5,900
26,000
Spolaore et al., 2006
Spolaore et al., 2006
 
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