TABLE 3: Qualitative amino sugar and carbohydrate analysis
of
three species
of
Namib Desert Lichens.
Amino sugars and
carbohydrates
Glucosamine
...............
.
Galactosamine
..............
.
Monosaccharides
Arabinose
.................
.
Fructose
..................
.
Glucose
...................
.
Mannose
..................
.
Rhamnose
.................
.
Galactose
..................
.
Disaccharides
Lactose
...................
.
Maltose
...................
.
Omphalodium
convolutum
+
++
+
Parmelia
hottentotta
+
+++
+
(+)
Teloschistes
capensis
+
++
(+)
+ present
in
small amounts; + + present
in
intermediate amounts; + + + present
in
appreciable amounts;
(+)
doubtful; - absent.
SUMMARY
The thalli
of
three lichen species collected from the Namib Desert (Omphalodium
convolutum, Parmelia hottentotta and Teloschistes capensis) were analyse,d for their
crude protein content, amino acid composition
of
the proteins and the sugar composi-
tion
of
the carbohydrates.
The crude protein content, calculated from the total nitrogen content as determined
by
means of the conventional Kjeldahl method, was found to
be
unexpectedly high in
all
three cases (14,42% for
O.
convolutum, 16,24% for
P.
hottentotta and 13,45%
for the
T.
capensis.) The amino acid composition
of
the thallus proteins was deter-
mined by means of an automatic amino acid analyser after acid hydrolysis. The range
of
amino acids found was similar to those found in higher plants and micro-organisms,
and none of the less commonly occurring amino acids was
d~tected.
The highest con-
centration
of
amino acid found was that
of
glutamate
in
P.
hottento tta.
Ther~
was
a notable absence
in
all three cases
of
cystine, hydroxy-proline and ornithine. The
digestibility
of
the thalli by ruminants as
well
as non-ruminants was not determined
accordingly, no conclusions could
be
drawn regarding the usefulness of the lichen
thalli as a food source.
Carbohydrates were analysed. by acid hydrolysis and thin layer chromatography.
Fructose and glucosamine were detected
in
all
three species, the former in appresJable
amounts. Glucose was detected
in
only two of the three bases, whereas galactose and
lactose were found
in
only one species. \ .
;
Reference has also been made to the role
of
lichens
as
a food source for animals in
the area.
. I
Plates
of
the three lichen species are presented.
42
Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2012)
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