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Temperature is a very important parameter that
affect both culture growth and exopolysaccharide
production. In this case the optimum temperature for
scleroglucan production is in the range of 20-37°C
and at 28
0
C for culture growth. At less than 28°C,
oxalic acid will gradually form which has an adverse
effect on the production of scleroglucan (Survase,
2007).
pH affects the physiology of microorganism such
as its solubility, nutrition and enzyme activity. The
optimum pH for exopolysaccharide production can
differ from the pH for culture growth. Generally the
optimum pH for scleroglucan synthesis is between
4.0 and 5.5 (Castillo et al, 2015). Aeration and
agitation optimization are the most important factors
for controlling cell growth and scleroglucan
production because it can increase the rate of
formation of metabolites and oxygen from liquid
medium to cells.
Substrates used in scleroglucan production are
for example sucrose, condensed corn solubles,
coconut water, molasses, sugar cane juice, and
glucose (J.I Farina.1998, Fosmer.2010). Liquid
sugar syrup produced from tapioca flour can be used
as a substrate because it can shorten the scleroglucan
production chain. Liquid sugar is easy to obtain
even if its utilization is limited only as a raw
material for the food and beverage industry, thus it is
expected a diversification step will emerge from
liquid sugar syrup which is made from local raw
materials and spread throughout Indonesia (Djenar
et al, 2017).
2 EXPERIMENTAL DETAILS
2.1 Microbial Preparation
At this stage regeneration of fungal S.rolfsii on :
a) Potato dextrose Agar (PDA) medium
containing potato, dextrose and agar ,
incubated at 28°C for 5-7 days.
b) Modified PDA medium containing potato,
dextrose, beef extract, KH
2
PO
4
, K
2
HPO
4
and
agar, incubated 28°C for 5-7 days.
2.2 Production of S.rolfsii Inoculum
2.2.1 Production of S.rolfsii inoculum in
Potato Dextrose Broth (PDB)
Potato Dextrose Broth medium was prepared by
dissolving 1.0 g potato, 0.1 g dextrose, 0.1 mg
CaCO
3
, 0.1 mg MgSO
4
7H
2
O in erlenmeyer
containing 5 mL of distilled water. The medium then
sterilized for 20 minutes at 121°C and 1.4 atm. The
stock culture S.rolfsii in PDA was inoculated to the
PDB medium and incubated at 28°C for 48 hours
and stirred at 150 rpm. Furthermore, this active
inoculum will be used to make S. rolfsii growth
medium.
2.2.2 Production of S.rolfsii inoculum in
modified Potato Dextrose Broth (PDB)
Potato Dextrose Broth medium was prepared by
dissolving 1.0 g potato, 0.1 g dextrose, 0.1 mg
CaCO
3
, 0.1 mg MgSO
4
7H
2
O, 0.0115 g K
2
HPO
4
,
0.0591 g KH
2
PO
4
and 0.005 g beef extract in
erlenmeyer containing 5 mL of distilled water. The
medium then sterilized for 20 minutes at 121°C and
1.4 atm. The stock culture S.rolfsii in PDA was
inoculated to the PDB medium and incubated at
28°C for 48 hours and stirred at 150 rpm.
Furthermore, this active inoculum will be used to
make S. rolfsii growth medium.
2.3 Experimental Work
In this step, aerobic fermentation was done in
variation of growth medium at 170 rpm, pH 5, at 30-
35 °C using 5% and 7% liquid sugar as substrate
(Table 1)
Table 1: Variation of growth medium and substrate
concentration on scleroglucan production.
Pasteurization. The pasteurization was done at 90°C
for 25 minutes. The pasteurized fermentation was
separated between scleroglucan solution and its
cells using centrifugation.
Purification and precipitation. Precipitation of
scleroglucan was done by adding an organic solvent
of isopropyl alcohol (IPA) with a ratio of 3: 1 (v / v)
to the supernatant. The obtained precipitate was
then dried in an oven at 50°C, weighed, and the
yield and % conversion were calculated.
EIC 2018 - The 7th Engineering International Conference (EIC), Engineering International Conference on Education, Concept and
Application on Green Technology
426