119
circinelloides from 1985 to 1990. Earlier, GLA was mainly obtained from evening
primrose seeds making the oil expensive, but this new technology brought down the
prices to a great extent (Ratledge 2013).
PUFAs have diverse roles in our body ranging from gene regulation to production of metabolites that have important biological roles. They act as a precursor to a
number of eicosanoids and docosanoids involved in inflammatory responses of our
body. Arachidonic acid (ARA) acts as a precursor for eicosanoids with proinflammatory roles, while ω-6 series eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) act as precursors for the synthesis of anti-inflammatory compounds
(Czumaj and Śledziński 2020). This distinction in the role of the two omega families is what makes the ratio of ω-6 and ω-3 an important factor for cardiovascular
health and inflammatory responses (Sakuradani et al. 2009).
7.2 Oleaginous Fungi
Oleaginousity is a property of certain microorganisms to accumulate high amount
of lipids in their cells usually in the form of triacylglycerol (Laoteng et al. 2011).
Generally, microbes that store 20% or more lipids with respect to their cell dry
weight are regarded as oleaginous. Some of these species are also able to synthesize
long-chain unsaturated fatty acids which make them an attractive candidate for
commercial PUFA production in large quantities (Khot et al. 2020).
In the kingdom fungi, PUFA is mainly produced by oleaginous moulds. Several
genera including Mortierella, Trichoderma, Pythium and Aspergillus are able to
produce essential PUFAs (Verma et al. 2020). Yeasts have been exploited in food
and beverage industries since 6000 BC. One of the earliest yeast species known to
mankind is Saccharomyces cerevisiae (McNeil and Stuart 2018). Therefore, their
commercial exploitation in production of PUFA is highly sought-after. Oleaginous
yeasts are well studied and some species are even reported to accumulate up to 80%
lipids w/w of their cell dry weight. Common genera of oleaginous yeasts include
Rhodosporidium, Cryptococcus, Candida, Yarrowia, Trichosporon and Lipomyces
(Patel et al. 2020). However, oleaginous strains of yeasts are unable to produce
PUFA naturally. Therefore, genetic manipulation techniques have been employed in
them to produce economically important PUFA (Bellou et al. 2016). Since these
species are oleaginous, endogenous saturated/monounsaturated fatty acids synthesized by these species can be directed towards a high level of PUFA synthesis. One
of the models of oleaginous yeast for PUFA production is Yarrowia lipolytica. It is
a GRAS fungus that can accumulate up to 50% of its cell dry weight as lipids and is
known for its ability to utilize hydrophobic substrates. DuPont, a US-based company, has commercially exploited this species for EPA production by genetically
engineering a strain that overexpresses 30 genes mainly associated with fatty acid
desaturation and elongation and downregulating 4 genes involved in lipid degradation. Production of EPA as high as 56.6% of total fatty acid was reported in these
strains (Gemperlein et al. 2019). Other than Y. lipolytica, Lipomyces starkeyi and
7 Production of Polyunsaturated Fatty Acids by Fungal Biofactories…
circinelloides from 1985 to 1990. Earlier, GLA was mainly obtained from evening
primrose seeds making the oil expensive, but this new technology brought down the
prices to a great extent (Ratledge 2013).
PUFAs have diverse roles in our body ranging from gene regulation to production of metabolites that have important biological roles. They act as a precursor to a
number of eicosanoids and docosanoids involved in inflammatory responses of our
body. Arachidonic acid (ARA) acts as a precursor for eicosanoids with proinflammatory roles, while ω-6 series eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) act as precursors for the synthesis of anti-inflammatory compounds
(Czumaj and Śledziński 2020). This distinction in the role of the two omega families is what makes the ratio of ω-6 and ω-3 an important factor for cardiovascular
health and inflammatory responses (Sakuradani et al. 2009).
7.2 Oleaginous Fungi
Oleaginousity is a property of certain microorganisms to accumulate high amount
of lipids in their cells usually in the form of triacylglycerol (Laoteng et al. 2011).
Generally, microbes that store 20% or more lipids with respect to their cell dry
weight are regarded as oleaginous. Some of these species are also able to synthesize
long-chain unsaturated fatty acids which make them an attractive candidate for
commercial PUFA production in large quantities (Khot et al. 2020).
In the kingdom fungi, PUFA is mainly produced by oleaginous moulds. Several
genera including Mortierella, Trichoderma, Pythium and Aspergillus are able to
produce essential PUFAs (Verma et al. 2020). Yeasts have been exploited in food
and beverage industries since 6000 BC. One of the earliest yeast species known to
mankind is Saccharomyces cerevisiae (McNeil and Stuart 2018). Therefore, their
commercial exploitation in production of PUFA is highly sought-after. Oleaginous
yeasts are well studied and some species are even reported to accumulate up to 80%
lipids w/w of their cell dry weight. Common genera of oleaginous yeasts include
Rhodosporidium, Cryptococcus, Candida, Yarrowia, Trichosporon and Lipomyces
(Patel et al. 2020). However, oleaginous strains of yeasts are unable to produce
PUFA naturally. Therefore, genetic manipulation techniques have been employed in
them to produce economically important PUFA (Bellou et al. 2016). Since these
species are oleaginous, endogenous saturated/monounsaturated fatty acids synthesized by these species can be directed towards a high level of PUFA synthesis. One
of the models of oleaginous yeast for PUFA production is Yarrowia lipolytica. It is
a GRAS fungus that can accumulate up to 50% of its cell dry weight as lipids and is
known for its ability to utilize hydrophobic substrates. DuPont, a US-based company, has commercially exploited this species for EPA production by genetically
engineering a strain that overexpresses 30 genes mainly associated with fatty acid
desaturation and elongation and downregulating 4 genes involved in lipid degradation. Production of EPA as high as 56.6% of total fatty acid was reported in these
strains (Gemperlein et al. 2019). Other than Y. lipolytica, Lipomyces starkeyi and
7 Production of Polyunsaturated Fatty Acids by Fungal Biofactories…