Biology Reference
In-Depth Information
FIGURE 2.3
Phospholipid analysis of LD from S. cerevisiae. Two-dimensional TLC of individual
phospholipids from S. cerevisiae LD was performed as described in
Section 2
. Cells were
grown to the stationary phase on glucose medium. Lipids were extracted and separated using
chloroform/methanol/25% ammonia (65:35:5; per vol.) as a solvent system for the first
dimension; and chloroform/acetone/methanol/acetic acid/water (50:20:10:10:5; per vol.) as
a solvent system for the second dimension. Start, starting point of the separation; LP,
lysophospholipids; PI; phosphatidylinositol; PS, phosphatidylserine; PA, phosphatidic acid;
PC, phosphatidylcholine; PE, phosphatidylethanolamine; CL, cardiolipin; DMPE,
dimethylphosphatidylethanolamine.
(
Athenstaedt et al., 2006; Ivashov et al., 2012; Leber et al., 1994
). In contrast to
S.
cerevisiae
, where nearly equal amounts of TG and SE form the hydrophobic core of
LD, TG is the major and predominant nonpolar lipid class in
P. pastoris
and
Y. lipolytica
(
Fig. 2.4
). Only minor amounts of SE can be found in LD from these
yeast species. The amount of phospholipids is similar in all three yeasts.
The abovementioned yeast genera do not only differ in the relative distribution of
nonpolar lipid classes in LD, but also in the absolute amount of lipids.
Table 2.1
shows total amounts of lipids per mg protein in LD isolated from
S. cerevisiae
,
P. pastoris
, and
Y. lipolytica
grown to the stationary phase on glucose as a carbon
source. These data demonstrate that the methylotrophic yeast
P. pastoris
is able
to accumulate TG at much higher amount than
S. cerevisiae
cultivated under stan-
dard conditions. Total amounts of TG can be strongly increased by growing yeast
cells on carbon sources different from glucose. As an example,
S. cerevisiae
grown
on oleate containing medium shows a
3-fold increase of total TG (
Grillitsch et al.,
2011
). In
Y. lipolytica
, amounts of TG can be increased up to 40% when industrial
fats or glycerol are used as carbon sources (
Papanikolaou & Aggelis, 2002
).
