2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 33 -
Fig. 2. Ethanol productivity of S. cerevisiae Kyokai no.7 and
baker’s yeast S. cerevisiae at 24 and 48 hours.
Fermentation of bio-ethanol is primary associated
product whereas increase of biomass will increase
formation of product. Fig 3 showed cell biomass
concentration for both strain in sterilized sap. Since
fructose was not detected by HPLC after 48 hours
fermentation, this proved that both yeast have ability to
consume others substrate besides glucose.
Fig. 3. Cell biomass concentration of
S. cerevisiae
Kyokai no.7
and baker’s yeast
S. cerevisiae
in 48 hours.
Table 1 summarized the fermentation data for both
strain in the sap.
T
ABLE
1
S
UMMARIZED OF DATAFOR DIFFERENT STRAIN FOR BIO
-
ETHANOL
PRODUCTION FROMTHE FERMENTATION OF OIL PALM TRUNKS SAP
Parameter
Strain
S. cerevisisiae
Kyokai no.7
Baker’s yeast S.
cerevisiae
Maximum
biomass
(mg/L)
1268.7
993.6
Maximum
ethanol
(mg/L)
10114.1
6688.6
Glucose
consumption
until 48 h (mg/L(h
-1
))
434.0
439.2
Growth rate at 24 h
(mg/L(h
-1)
)
34.2
22.4
Growth rate at 48 h
(mg/L(h
-1)
)
16.8
11.2
Parameter
Strain
S. cerevisisiae
Kyokai no.7
Baker’s yeast S.
cerevisiae
Ethanol productivity at
24 h
421.4
257.7
Ethanol yield
P/S
(g/(g
-1
)
0.454
0.317
Percentage conversion %
88.9
62.1
B. Effects of sterilized medium on bio-ethanol
production
Figure 3 showed the outcome of
S. cerevisiae
Kyokai
no.7 fermentation in heat sterilized and non-sterilized
sap.
Fig. 4. Fermentation Profile of
S. cerevisiae
Kyokai no.7 and
baker’s yeast
S. cerevisiae
in 48 hours. Blue lines represent ethanol
and glucose concentration for fermentation in sterilized medium. Red
lines represent ethanol and glucose concentration for fermentation in
non-sterilized medium.
From pre-streaked test, we observed growth of
contaminant inside non-sterilized sap. This can
explained the reason of low ethanol production in non-
sterilized sap. Other microbes might utilize substrate in
the sap to produce other product alongside ethanol.
Based on economical view, it is somewhat important to
pretreated sap rather than obtained low ethanol. Further
screening should be done to know the types of microbes
that competed with
S. cerevisiae
in non-sterilized
sap.Table 2 summarized the fermentation data for
S.
cerevisiae
Kyokai no.7 in both sap.
T
ABLE
2
S
UMMARIZED OF DATAFOR BIO
-
ETHANOL PRODUCTION FROMTHE
FERMENTATION OF OIL PALM TRUNKS SAP IN DIFFERENT MEDIUM
Parameter
Sap medium
Sterilized sap
Non-sterilized sap
Maximum
biomass
(mg/L)
1050.6
923.1
Maximum
ethanol
(mg/L)
8731.1
5244.1
Glucose consumption
(mg/L(h
-1
))
358.5
309.0
Growth rate at 24 hour
(mg/L(h
-1)
)
20.7
17.6
Growth rate at 48 hour
(mg/L(h
-1)
)
16.8
9.9
Ethanol yield
P/S
(g/(g
-
0.465
0.354
0
2000
4000
6000
8000
10000
0
4000
8000
12000
16000
20000
0 10 20 30 40 50
ethanol concentration (mg/l)
glucose concentration (mg/l)
time (hour)
non-sterile
sterile
