Food Lipids: Chemistry, Nutrition, and Biotechnology

as 80% lipids of which about 90% are triacylglycerols (10). However, cell yields of
such organisms are rather low, and the presence of potentially toxic lipids in their
biomass restricts the usefulness of such microorganisms as producer of triglyceriderich
single-cell oils.
2. Polyunsaturated Fatty Acids
Polyunsaturated fatty acids of the �3 and �6 series, which are precursors of eicosanoids,
are of great interest in specialty products, such as ‘‘Nutraceuticals,’’ due to
their ability to modulate the metabolism of eicosanoids, which play a great role in
health and disease (see Chapters 17–20 in Part IV of this book).
Several species of microalgae are known to produce large proportions of �3
and �6 polyunsaturated fatty acids and eicosanoids in their biomass (11–13 and
Table 4). Thus, a docosahexaenoic acid-containing single-cell oil (DHASCO) containing
about 40% docosahexaenoic acid (22:6 �3) is produced commercially from
the biomass of the heterotrophic, nonphotosynthetic marine algae, Crypthecodinium
cohnii (14,15).
Selected fungi that have been reported to produce �3 and �6 polyunsaturated
fatty acids in their biomass are listed in Table 5. Especially, Mucor javanicus (5),
Mortierella isabellina and other Mortierella species (8,30,31) have been used for the
commercial production of oils containing �-linolenic acid (18:3 �6) as substitute for
rather expensive plant oils, such as those from seeds of borage (Borago officinalis),
evening primrose (Oenothera biennis), black currant, and other Ribes spp. that also
contain 10–25% �-linolenic acid. Typically, a commercially produced oil from the
biomass of a Mortierella sp. contains as major constituent fatty acids palmitic (27%),
stearic (6%), oleic (44%), linoleic (12%), and �-linolenic acid (8%) (30). Optimization
of culture conditions of a Mortierella ramanniana species has yielded an oil
containing 18% �-linolenic acid (32). Similarly, commercially produced anachidonic
acid-containing single-cell oil (ARASCO) from the biomass of Mortierella alpina
contains as much as 40% arachidonic acid (20:4 �6) (33). Recently, culture conditions
have been optimized for the production of an oil containing about 40% dihomo-
�-linolenic acid (20:3 �6) from the biomass of Mortierella alpina (34).
Table 4 Levels of Major Constituent Polyunsaturated Fatty
Acids in Biomass of Lipid-Accumulating Microalgae
Organism
Major polyunsaturated fatty acid
Fatty acid a
(% w/w of total
fatty acids)
Spirulina platensis 18:3�6 21
Dunaliella tertiolecta 18:3�6 32
Porphyridium cruentum 20:4�6 60
Chlorella minutissima 20:5�3 45
Navicula saprophilla 20:5�3 22
a Fatty acids are designated by number of C atoms (left of colon) and number
of cis double bonds (right of colon).
Source Ref. 2.
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.