EFFECT OF METAL IONS ON THE PRODUCTION OF GLUCONIC ACID BY ASPERGILLUS NIGER

Abstract

Different cultures of Aspergillus niger isolated and selected in biochemistry lab, Quaid-iAzam University, Islamabad were studied for gluconic acid production using shake flask culture methods. Cane molasses was provided as a carbon source. Other culture conditions such as pH 5.5, temperature 300C and shaking speed of200 rpm were optimized. Addition of different metal ions Zn ++ and Mg ++ in their salts stimulated gluconic acid production when used in minimal quantities i.e. 0.05g!L, O.062g!L respectively. At higher concentrations of metal ions the gluconic acid production is adversely effected but the fimgal growth increased because gluconic acid production is an oxidative process and increased metal concentrations resulted in lack of control on activity of enzymes of the oxidative pathway.