Ribonuclease production of Rhizopus oryzae IFO 4697 under metal ion stress in liquid culture

Abstract

Rhizopus oryzae IFO 4697 was found to produce intracellular ribonuclease (RNase), and its growth and activity could be regulated under selected metal ion stress. The addition of Fe 2ϩ , Mg 2ϩ and Zn 2ϩ to the SLSR medium was essential to growth and RNase production. Ca 2ϩ and Mo 6ϩ stimulated RNase production. It is concluded that the addition of 100 mg/ml Ca 2ϩ , 5 mg/ml Mo 6ϩ , 0.7 mg/ml Zn 2ϩ , 2 mg/ml Fe 2ϩ , and 49 mg/ml Mg 2ϩ to the SLSR medium was the best condition for producing RNase in high specific activity (3780 U/mg protein). This result indicates that a metal ion-regulated liquid medium is an efficient culture method for RNase production.

Microbial ribonucleases (RNases): production and application potential

“…Under optimized culture conditions, maximum enzyme activity of 3000 U/ml on the 5th day of fermentation has been achieved (Chacko et al 1996). Morita et al (2002) also reported the positive effects of various metal ions (Fe 2? , Mg 2?…”