Effect of scandium on production of amylase and protease by Bacillus subtilis in different culture media

The effect of scandium, one of the rare earth elements, on protease activity secreted into the culture supernatant was investigated in NG and LG media. The addition of scandium improved slightly the protease activity of Bacillus subtilis by 1.42 times compared to that with no addition of scandium in NG medium. On the other hand, no effect of scandium addition on protease activity was observed in LG medium. Furthermore, the effect of scandium on amylase activity was investigated in LG medium. The amylase activity was increased 1.5-fold after 72 hours cultivation compared to that with no scandium. However, the value was considerably lower than the previously reported 3.3-fold value in the NG medium. It was suggested that the medium composition reduce the stimulation effect of scandium on enzyme production.