The profile of enzymes relevant to solvent production during direct fermentation of sago starch by <Emphasis Type="Italic">Clostridium saccharobutylicum</Emphasis> P262 utilizing different pH control strategies |
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Authors: | Madihah Md Salleh Liew Shiau Tsuey Arbakariya Bin Ariff |
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Institution: | (1) Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia |
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Abstract: | The profile of enzymes relevant to solvent production during direct fermentation of sago starch by Clostridium saccharobutylicum P262 in a 2 L stirred tank fermenter was determined utilizing different pH control strategies. During fermentation without
pH control (initial pH of 6), the specific activity of crotonase, thiolase, and β-hydroxybutyryl-CoA dehydrogenase increased
proportionally with solvent production. The highest crotonase (3,450.7 kat) and phosphotransbutyrylase activity (1,475.6 kat)
was observed in fermentation where pH was maintained at 5 during the acidogenic phase and corresponded to a fairly high acid
accumulation but low solvent production. During fermentation with a controlled pH of 5.25 during the sol-ventogenic phase,
the highest thiolase specific activity (255.7 kat) was obtained and corresponded to the highest production of acetone. On
the other hand, the highest specific activities of crotonase, β-hydroxybutyryl-CoA dehydrogenase, and phosphotransbutyrylase
were observed at pH 5.5 and corresponded to the highest production of ethanol and butanol. Butyryl-CoA dehydrogenase had no
significance role in solvent fermentation. These results suggested that pH control strategies were important for improvement
of solvent production during direct fermentation of sago starch by C. saccharobutylicum. |
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Keywords: | sago starch Clostridium saccharobutylicum solventogenesis acetogenesis enzymes relevant to solvent fermentation |
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