Genomics and Applied Biology, 2017, Vol.8, No.3, 17-25
18
lactose and fructose during fermentation. The motility test also set a clear margin of identification between
C.
manihot
and
L. plantarum
in that
L. plantarum
was motile whereas
C. manihot
was not.
Table 1 Tests for identification of bacteria
Shape
Biochemical tests for identification of bacteria
Gramm Test
Catalase Test
Motility Test
Acid from Glucose
Gas from Glucose
Acid from Lactose
Gas from Lactose
Acid from Fructose
Gas from Fructose
Organism Present
Short rod
+
+
-
-
-
+
-
+
-
Corynebacteria manihot
Long rod
+
+
+
+
+
+
+
+
+
Lactobacillus plantarum
Note: Summary of biochemical test used in identifying bacterial pure cultures obtained; Key: (+) Positive test, (-) Negative test
1.2 Fungi identification
The other microorganisms isolated from the effluents were non filamentous fungi;
Geotrichum candidum
and
Sacharomyces exguus
. The fungi were differentiated by considering their shapes and spore type.
G. candidun
produces condidiospores as
S. exguus
produces buds.
1.3 Linamarin (mgHCN/Kg) valu1es obtained during fermentation of wet cassava peels
Linamarin which is the cyanogenic glucoside present in the cassava peels decreased as the time of fermentation
increased in all the treatments including the control experiment. The highest and the lowest values of linamarin
were recorded in 0h and 96h of fermentation in all the treatments and control experiment respectively. The control
experiment had the least amount of linamarin value of 247.66 mgHCN/Kg whereas the highest linamarin value of
317.86 mgHCN/Kg was observed in the
G. candidum
treatment at the beginning of fermentation.
At 24 hours of fermentation, the control experiment had the least amount of linamarin value of 91.23 mgHCN/Kg
while the highest value of 190.56 mgHCN/Kg was recorded in
C. manihot’
s
treatment. Decrease in linamarin
occurs daily in all the treatments. At 72 hours of fermentation
L.
plantarum
,
G. candidum,
and
S.exguus
s’
treatments had linamarin values of 53.53, 53.33 and 51.00 mgHCN/Kg which were not significantly different by
Tukey’s Test at P < 0.05. Nevertheless, these linamarin values (53.53, 53.33 and 80.03 mgHCN/Kg) obtain from
L.
plantarum
,
G. candidum,
and
S.exguus
s’ treatments at 72 hours of fermentation were significantly different from
the linamarin values of 20.11, 77.56 and 80.03 mgHCN/Kg obtained from the mixed microbes, the control
experiment and
C. manihot’s
treatments respectively. After 72h of fermentation, the highest linamarin value of
80.03 mgHCN/Kg was recorded in
C. manihot’
s treatment whereas; the lowest value of linamarin was 20.11
mgHCN/Kg was recorded in the mixed culture treatment (Table 2).
Table 2 Linamarin (mgHCN/Kg) values obtained during fermentation of milled cassava peels
Fermenting Organism
Linamarin (mgHCN/Kg) values obtained during fermentation /period of fermentation (hours)
0
24
48
72
96
Control
247.66 ±5.0
a
91.23 ±3.9
a
90.99 ±3.7
b
77.56 ±7.9
c
48.67 ±4.0
a
Lactobacillus
sp
281.86 ±4.5
b
126.43 ±6.4
b
88.88 ±1.9
b
53.53 ±0.7
b
21.67 ±5.9
a
C. manihot
.
280.00 ±5.8
b
190.56 ±3.9
d
124.66 ±4.1
c
80.03 ±5.8
c
53.20 ±0.2
a
S. exguus
317.66 ±2.0
c
175.46 ±9.7
cd
84.67 ±1.2
b
51.00 ±2.2
b
22.21 ±6.2
a
Geotrichum candidum
317.86±1.9
c
160.20 ±6.0
c
88.66 ±1.8
b
53.33 ±0.0
b
20.11 ±5.8
a
Mixed microbes
275.75 ±9.8
b
124.56 ±4.0
b
58.10 ±4.2
a
20.11 ±1.7
a
15.20 ±1.3
a
Note: Each value is Means ±Standard deviation of three replicates. Values followed by the same letter in the same column are not
significantly different using Tukey’s Test at *(P < 0.05)
