Microbial Production of

-Linolenic Acid

The demand for EPO began to increase in the mid-1970s because of the many

claims of its benefits. With this came a concomitant increase in price as demand
began to exceed the supply. Top prices for EPO in the mid-1970s and early 1980s
reached over $50 per kg (i.e., over $50,000 per ton). It was then one of the highest,
if not the highest, valued triacylglycerol oils produced.

2.4.2 T

EARCH

FOR

THE

“B

EST

” GLA-P

RODUCING

UNGUS

The monopoly enjoyed by EPO led to searches for alternatives sources of GLA. The
presence of GLA in

Phycomyces

fungi had been known since the 1940s [18], and

it was subsequently found to be a common fatty acid in fungi classified as “the lower
fungi,” which included the genus of

Phycomyces

[19–21]. The lower fungi are

sometimes known collectively as the Phycomycetes order but are more correctly
classified into two subgroups: Mastigomycotina and Zygomycotina, with members
of both groups producing GLA in their lipids. Interestingly, no other group of
microorganism — bacteria, yeast, or higher fungi — produce GLA, though it is found
in many marine and freshwater algae.

With the known occurrence of GLA in fungal microorganisms, it was therefore

attractive to consider a biotechnological route for its production. Up to this time, no
process had been developed on a commercial scale for the production of any micro-
bial oil. Nevertheless, it seemed that if an appropriate organism could be identified,
then production of a GLA-SCO should be feasible using the technology that was
available for large-scale cultivation of microorganisms, including filamentous fungi.

Work began in the author’s laboratory in 1976 to identify a possible fungal

source of GLA. Over 300 species and strains were eventually screened over the next
6 years for GLA production. Table 2.1 lists the main genera that were examined.
Within each genus, a diversity of species was examined to ensure that as wide a net
as possible was cast to find the most promising species. All organisms were obtained

TABLE 2.1
Genera of the Lower Fungi (Phycomycetes)
Screened for GLA Production

Absidia

Mucor

Basidiobolus

Phlyctochytrium

Choenephora

Phycomyces

Cunninghamella

Pythium

Delacroixia

Rhizopus

Entomophthora

Zygorhynchus

Mortierella

In each case, a number of representative species were screened

for growth performance, lipid production, and GLA content of

the lipids. Those species that appeared to be the most promising

(see text) were then examined in detail. See Table 2.2.

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