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Sains Malaysiana 45(3)(2016): 393–400 An Evaluation of Fermentation Period and
Discs Rotation Speed of Rotary Discs Reactor for Bacterial Cellulose
Production (Penilaian Tempoh Penapaian dan Kelajuan
Putaran Cakera melalui Reaktor Cakera Berputar untuk Pengeluaran
Selulosa Bakteria) KHAIRUL AZLY
ZAHAN1,3,
NORHAYATI
PA’E1
& IDA IDAYU MUHAMAD1,2* 1Bioprocess Engineering
Department, Faculty of Chemical Engineering, Universiti Teknologi
Malaysia, 81310 Johor Bahru, Johor Darul Takzim, Malaysia 2Cardio Engineering
Centre IJN-UTM, Universiti Teknologi Malaysia, 81310 Johor Bahru,
Johor Darul Takzim, Malaysia 3Section of Bioengineering
Technology, Malaysian Institute of Chemical and Bioengineering
Technology, Universiti Kuala Lumpur, 78000 Alor Gajah, Melaka
Bandar Bersejarah, Malaysia Diserahkan: 6 Januari
2015/Diterima: 1 September 2015 ABSTRACT Acetobacter xylinum strains
are known as efficient producers of cellulose. A. xylinum
is an obligate aerobic bacterium that has an oxygen-based metabolism.
The dissolved oxygen (DO)
concentration in a rotary discs reactor (RDR) is one of the most important
factors that need to be observed during the cellulose synthesis
by these bacteria. In this study, the effects of different discs
rotation speed (5, 7, 9 and 12 rpm) and fermentation period (3,
4, 5 and 6 days) on the DO
concentration and production of bacterial cellulose
in a 10-L RDR were
examined. The highest yield was obtained at 7 rpm with a total
dried weight of 28.3 g for 4 days fermentation. The results showed
that the DO concentration
in the 10-L RDR increased in the range of 13 to 17% with increasing
of discs rotation speed from 7 to 12 rpm. However, fermentation
with high discs rotation speed at 12 rpm reduced the bacterial
cellulose production. Analysis of data using Statistica 8.0 showed
a high coefficient of determination value (R2 =
0.92). In conclusion, discs rotation speed gave more significant
effect on the DO
concentration and production of bacterial cellulose
in 10-L RDR compared to fermentation
period. This was further combined with synergistic
effect from sufficient consumption of oxygen for the enhanced
production of bacterial cellulose and providing the controlled
environment for encouraging bacterial growth throughout the fermentation
process. Keywords: Acetobacter
xylinum; bacterial cellulose; discs rotation speed; dissolved
oxygen; fermentation period; rotary discs reactor (RDR) ABSTRAK Strain Acetobacter
xylinum dikenali sebagai pengeluar selulosa yang cekap. A.
xylinum adalah bakteria aerobik yang mempunyai metabolisme
berasaskan oksigen. Kepekatan oksigen terlarut (DO) di dalam reaktor cakera berputar
(RDR)
adalah salah satu faktor terpenting yang perlu diperhatikan semasa
pengeluaran selulosa oleh bakteria ini. Dalam kajian ini, kesan
daripada kelajuan putaran cakera yang berbeza (5, 7, 9 dan 12
rpm) dan tempoh penapaian (3, 4, 5 dan 6 hari) terhadap kepekatan
oksigen terlarut (DO)
dan jumlah pengeluaran selulosa di dalam 10-L RDR telah
dikaji. Hasil tertinggi telah diperoleh pada kelajuan putaran
cakera 7 rpm dengan jumlah berat kering sebanyak 28.3 g selama
4 hari penapaian. Keputusan juga menunjukkan bahawa kepekatan
oksigen terlarut (DO)
di dalam 10-L RDR meningkat dalam julat 13 hingga 17% dengan peningkatan
kelajuan putaran antara 7 hingga 12 rpm. Walau bagaimanapun, penapaian
dengan kelajuan cakera yang tinggi iaitu pada 12 rpm menyebabkan
pengeluaran selulosa berkurangan. Analisis data menggunakan Statistica
8.0 menunjukkan pekali nilai penentuan (R2 = 0.92) yang tinggi. Kesimpulannya,
kelajuan putaran cakera memberikan kesan yang lebih besar terhadap
kepekatan oksigen terlarut dan penghasilan selulosa di dalam 10-L
RDR
berbanding tempoh penapaian. Ini seterusnya digabungkan
dengan kesan sinergistik daripada penggunaan oksigen yang mencukupi
bagi meningkatkan pengeluaran selulosa dan menyediakan persekitaran
terkawal untuk menggalakkan pertumbuhan bakteria sepanjang proses
penapaian. Kata kunci: Acetobacter xylinum; kelajuan putaran cakera; oksigen terlarut;
reaktor cakera berputar (RDR); selulosa bakteria;
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*Pengarang untuk surat-menyurat; email:
idayu@cheme.utm.my
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