Synergistic hydrolysis of crude corn starch by alpha-amylases and glucoamylases of various origins
2001
Liakopoulou-Kyriakides, M. | Vasilakē-Karakatsanē, Agapē | Stamatoudis, M. | Psomas, S.
Four alpha-amylases and two glucoamylases from various sources, in eight combinations, were used to study the synergistic hydrolysis of crude corn starch at various temperatures. At 40 and 50 degrees C, the combinations containing Rhizopus mold glucoamylase enhanced hydrolysis of corn starch compared with that obtained with the combinations from Aspergillus niger. At 60 degrees C, Rhizopus mold combinations gave low reaction yields as the enzyme was inactivated. The differences observed between alpha-amylases are smaller, with the exception of Bacillus licheniformis alpha-amylase, which presented more than twice the productivity of the other alpha-amylases, at all temperatures. In terms of substrate conversion at 5 hr of hydrolysis, the combination of B. licheniformis alpha-amylase with Rhizopus mold glucoamylase at 50 degrees C presents 76% substrate conversion, whereas, with all the other combinations, starch conversion was 13-73%. HPLC analysis of the reaction products obtained at 50 degrees C showed that the main product of corn starch hydrolysis was glucose at 85-100%. Further experiments showed that A. niger glucoamylase and B. licheniformis alpha-amylase were the only enzymes that retained their initial activity after incubation at the temperatures studied.
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