42
F. B. SHORLAND
b. Yeast and Mold Fats. It is well known that yeasts and molds
when cultured on suitable media will yield a high percentage of fat.
The fatty acids appear to be generally similar to those found in the
seed oils of many plants, the main constituents being oleic and linoleic
acids, together with lesser amounts of palmitic and stearic acids (see
Tables IX and X). The molds and yeasts are shown to elaborate similar
fats, the palmitic acid content in many instances approaching or even
exceeding the 25-30% characteristic of the depot fats of higher animals.
The stearic acid content is usually below 10%, but rises in Aspergillus
nidulans to 15.9%, which approaches the amount usually found in ruminant fats. The content of linoleic acid is variable, covering a wide range
from 5.7 to 49.7%. Considered collectively, the results show that the fats
of molds and yeasts contain no characteristic properties. The most
abundant acids—oleic, linoleic, palmitic, and stearic—are those most
commonly found in plant fats. Linolenic acid is usually present in trace
amounts, but in Neurospora crassa this acid amounts to 32% of the
total fatty acids (214). It is perhaps not surprising, in view of the
variability in the proportions of these commonly occurring fatty acids,
that fats of some yeasts or molds should correspond closely to those
found in higher plants and animals. Thus the fats of Penicillium lilacinum
and of pig fat are of similar fatty acid composition, and the composition
of the linoleic-rich molds and yeasts is not unlike that of cottonseed oil.
It is therefore not feasible from the types and distribution of the fatty
acids to deduce whether a given fat has come from a yeast or a mold
on the one hand, or from a plant or a pig on the other. It is thus not
always possible to correlate fatty acid composition and the classification
of species. Nevertheless, within the molds some specificity in fatty acid
composition is found. Phycomyces bhkesleeanus elaborates an unusual
isomer of linolenic acid together with tetracos-17-enoic and hexacosenoic
acids.
In the uredospore stage of the fungus Puccinia graminis var. tritici,
the glycerides contain as the main constituent palmitic acid (47.4%) with
minor amounts of linoleic (3.3%) and linolenic (6.3% acids) (219a), the
only other important acid being the unique cis-9,10-epoxyoctadecanoic
(up to 27%) along with ( + )-threo-9,10-dihydroxyoctadecanoic acid (up
to 5%) (219b). The last mentioned acid also occurs in the oil of Lycopodium clavatum spores belonging to the order Lycopodiales (219c).
The occurrence of other epoxy acids in seed fats will be referred to later.
2. Phanerogam Fats
As previously mentioned, fats other than seed, fruit-coat, and leaf
fats have not been investigated sufficiently to establish any useful re-
F. B. SHORLAND
b. Yeast and Mold Fats. It is well known that yeasts and molds
when cultured on suitable media will yield a high percentage of fat.
The fatty acids appear to be generally similar to those found in the
seed oils of many plants, the main constituents being oleic and linoleic
acids, together with lesser amounts of palmitic and stearic acids (see
Tables IX and X). The molds and yeasts are shown to elaborate similar
fats, the palmitic acid content in many instances approaching or even
exceeding the 25-30% characteristic of the depot fats of higher animals.
The stearic acid content is usually below 10%, but rises in Aspergillus
nidulans to 15.9%, which approaches the amount usually found in ruminant fats. The content of linoleic acid is variable, covering a wide range
from 5.7 to 49.7%. Considered collectively, the results show that the fats
of molds and yeasts contain no characteristic properties. The most
abundant acids—oleic, linoleic, palmitic, and stearic—are those most
commonly found in plant fats. Linolenic acid is usually present in trace
amounts, but in Neurospora crassa this acid amounts to 32% of the
total fatty acids (214). It is perhaps not surprising, in view of the
variability in the proportions of these commonly occurring fatty acids,
that fats of some yeasts or molds should correspond closely to those
found in higher plants and animals. Thus the fats of Penicillium lilacinum
and of pig fat are of similar fatty acid composition, and the composition
of the linoleic-rich molds and yeasts is not unlike that of cottonseed oil.
It is therefore not feasible from the types and distribution of the fatty
acids to deduce whether a given fat has come from a yeast or a mold
on the one hand, or from a plant or a pig on the other. It is thus not
always possible to correlate fatty acid composition and the classification
of species. Nevertheless, within the molds some specificity in fatty acid
composition is found. Phycomyces bhkesleeanus elaborates an unusual
isomer of linolenic acid together with tetracos-17-enoic and hexacosenoic
acids.
In the uredospore stage of the fungus Puccinia graminis var. tritici,
the glycerides contain as the main constituent palmitic acid (47.4%) with
minor amounts of linoleic (3.3%) and linolenic (6.3% acids) (219a), the
only other important acid being the unique cis-9,10-epoxyoctadecanoic
(up to 27%) along with ( + )-threo-9,10-dihydroxyoctadecanoic acid (up
to 5%) (219b). The last mentioned acid also occurs in the oil of Lycopodium clavatum spores belonging to the order Lycopodiales (219c).
The occurrence of other epoxy acids in seed fats will be referred to later.
2. Phanerogam Fats
As previously mentioned, fats other than seed, fruit-coat, and leaf
fats have not been investigated sufficiently to establish any useful re-