Amylase Production By A Thermophilic Bacterium, Bacillus Licheniformis BT5.9 Isolated From Changar Hot Spring, Malang Indonesia
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Date
2012-04
Authors
Han, Li Zhu
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Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
This study was carried out in order to search for thermophilic microorganisms with special interest as a source of thermostable amylases. Six samples which consisted of soils, water and sludge were taken from Changar Hot Spring in a volcanic area of Malang, Indonesia. The samples had temperature of 49.5 to 56.0ºC and pH of 5.7 to 6.5. Thirteen out of 34 of bacterial isolates were obtained from those samples and exhibited potential amylase producer, and isolate BT5.9 which was identified as Bacillus licheniformis BT5.9 through biochemical tests and 16S rRNA molecular analysis was chosen as the best amylase producer. The improvement of cultural conditions (initial medium pH of 5.0, cultivation temperature of 50ºC, agitation speed of 100 rpm and inoculum size of 1.7x108 cells/ml) and medium compositions (g/L: 20 g soluble starch, 2.5 g yeast extract, 1.0 g MgSO4 ·7H2O, 3.0 g Na2HPO4 , 0.1 g NaCl, 0.3 g FeSO4 ) produced the highest amylase production about 1.06 U/ml at 18 hours of cultivation time. There was an increment of 222.94% of amylase production obtained after the improvement of cultivation conditions and medium compositions. The study revealed that the enzyme production was not growth dependant. Purification process produced a single band on SDS-PAGE indicated that the purified amylase was obtained with a molecular weight of about 24.55 kDa. The activity of purified amylase was found optimum at the temperature of 70ºC and pH of 6.0 with 100% activity at those parameters for 60 minutes.
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Keywords
Thermophilic microorganisms with special interest , as a source of thermostable amylases