PURIFICATION AND CHARACTERIZATION OF A RAW STARCH-DIGESTIVE AMYLASE FROM NON-SULFUR PURPLE PHOTOSYNTHETIC BACTERIUM

A strain of non-sulfur purple photosynthetic bacteria could utilize raw starch from corn, potato and cassava efficiently as a source of electron donor for hydrogen production. At least two amylases were found in the culture grown under light-anaerobic conditions with raw corn starch as a carbon source. These two amylases could digest raw starch as well as soluble starch. One of them was purified as a homogeneous protein with DEAE-cellulose column chromatography, ultrafiltration with a membrane of Amicon XM 300, hydroxyapatite column chromatography, Toyopearl 55 HW gel filtration, and starch gel affinity chromatography. The activity of this amylase was reactivated specifically by calcium ion after the enzyme was treated by EDTA. The optimum temperature of the enzyme activity was 40 degree C and the activity was stable up to 45 degree C. The optimum pH was 6. 0 and the enzyme was quite stable at alkaline pH up to 12. 0. This enzyme is an amylase that can digest raw starch from corn, potato and cassava.