Production of Bacterial Amylase and Evaluation For Starch Hydrolysis
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Date
2018-05-03
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Addis Ababa University
Abstract
In starch Degrading industry, the first step to be preformed is gelatinization of starch granules at
elevated temperature. This process tends to form a viscose suspension, thus making mixing and
pumping a huge challenge. Therefore, to lower viscosity of starch paste thermo stable enzymes are
added for breaking down the polysaccharides into oligosaccharides by a process known as
liquefaction. Therefore, availability of these enzymes can be considered a prerequisite to start a
successful starch liquefaction and saccharification industry. The main objective of this study was,
therefore, to produce efficient microbial amylolytic enzymes for starch hydrolysis. One bacterial
isolate designated as AAU 2107 was isolated from locally collected samples. The enzyme has an
optimum activity at pH of 5.0 and 70°C. Addition of calcium in the reaction mixture was shown to
stabilize the enzyme. The isolate AAU 2107 was able to grow under solid state fermentation (SSF)
using wheat bran as a solid substrate. Optimum enzyme production was recorded at 32°C, and at
120 h of incubation and at a moisture content of 75%. Addition of peptone to the SSF medium as
an organic nitrogen supplement enhanced enzyme production. The enzyme was used to hydrolyze a
25 % (w/v) of starch at 70°C and pH 5.0, and the resulting hydrolysate was analyzed on TLC
plates. After 4 h hydrolysis, the TLC chromatogram showed release of glucose, maltose,
maltotriose, and other oligosaccharides, indicating that the enzyme is endo acting alpha amylase.
The results of this study show that amylase from AAU 2107 has a good potential to be used in
starch liquefaction and saccharification processes. The ability of the isolate to grow and produce
the enzyme under SSF using cheap agro industrial wastes could help to greatly reduce the
production cost of the enzyme.
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Keywords
Alpha-Amylase, Liquefying, Ca2+-Dependent, Starch Hydrolysis