Pembangunan bioproses penukaran bahan berlignoselulosa kepada gula penurun dan bioetanol
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Date
2011
Authors
Hong, Lim Sheh
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Abstract
Various types of lignocellulosic material were screened to obtain a maximum
reducing sugar through solid substrate fermentation system by using different types
of fungal strains. Production of lignocelluloses degrading enzymes on lignoeellulosic
material from each strain of fungus was varied with the types of lignocellulosic
material used. In this research, oil palm frond and Aspergillus niger USM AI 1 were
chosen as potential substrate and fungus for the production of reducing sugar after
the screening process. Production of reducing sugar by A. niger USM AI 1 on oil
palm frond was about 53.90 mg/ g substrate and fungal growth obtained was about
1.23 glucosamine/g substrate. The content of holocellulose in oil palm frond was
about 60.71% (w/w). Oil palm fronds were pretreated using physical and chemical
methods. Pretreatment process on the oil palm frond had caused the morphological
changes on its surface. Oil palm fronds that were autoclaved using water (OPFAuto)
were found to be the most effective pretreatment method resulting in enzyme
production of 70.20 mg/g substrate reducing sugar. Optimizations of physical and
chemical parameters were carried out in order to enhance the production of reducing
sugar for the solid substrate fermentation. After the optimization of physical and
chemical parameters the production of the reducing sugar achieved was 200.15 mg/g
substrate using shake flask system. The production of reducing sugar in shake flask
system was successfully increased to 180% after the optimization. Meanwhile, the
cultivation of A. niger USM All on OPF Auto in a tray system achieved maximum
reducing sugar production of 185.00 mg/g substrate. After optimization in a tray
system the production of reducing sugar resulted 35.75% increment compared to
before optimization of physical and chemical parameters. Reducing sugar obtained
from the OPF Auto hydrolysed by A. niger USM All through the solid substrate
fermentation were glucose, xylose and fructose which achieved 69.18%, 13.32% and
17.50%, respectively. Reducing sugar obtained was later fermented with a yeast
Saccharomyces cerevisiae for production of ethanol. Before optimization of physical
parameter, the concentration of ethanol production through a medium bottle system
was about 5.61 g/L, however after optimization of physical parameter, the
concentration of ethanol was increased to 23.10 g/L. Fermentation process of
ethanol before optimization in a fermenter able to produce 15.40 g/L ethanol and
achieved 20.51 g/L ethanol after optimization. In the single cell protein production,
Candida utilis was able to utilize the waste product of this ethanol distillation which
riched with xylose as a carbon source for the cell growth. About 91.11% of the
sugars were consumed, and the specific biomass production rate (Y 8 ) produced was
1.16 g biomass/g sugars. Therefore, a more efficient and economical pretreatment,
hydrolysis and the fermentation systems need to be developed to ensure the success
of this project.
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Keywords
Lignocellulolytic materials , Bioethanol