Abstract
Action of Bacillus circulans F-2 amylase on raw starches of various origins was studied in comparison with those of porcine pancreatic α-amylase and Streptococcus bovis α-amylase. Three amylases showed the highest digestive activity against mochi rice starch and the lowest activity against potato starch. Three amylases digest cereal starches such as corn starch at approximately the same rate. However, only B. circulans F-2 amylase could digest potato starch at a substantial rate.
Starch granules digested by B. circulans F-2 amylase were observed by scanning electron microscopy. Differences in digestion patterns observed among various starches were discussed in relation to the differences in environment of granule development.
Crosslinked starches prepared by the reaction between epichlorohydrin and raw starches were found to be effective carbon source for the production of B. circulans F-2 amylase. Different from raw potato starch, these starches can be autoclaved and so greatly facilitate the cultivation of this bacterium. Crosslinked potato starch is superior to crosslinked corn starch as, in the presence of the former, the bacterium produces higher amount of amylase with shorter cultivation period than in the presence of the latter.
