A NEW GLUCOSE-OXIDASE FROM ASPERGILLUS-NIGER - CHARACTERIZATION AND REGULATION STUDIES OF ENZYME AND GENE

A new glucose oxidase from Aspergillus niger was isolated and characte rized. The enzyme showed different kinetic and stability characteristi cs when compared to a commercially available batch of A. niger glucose oxidase. The gene encoding the new glucose oxidase was isolated and D NA sequence analysis of the coding region showed 80% identity to the s equence of a glucose oxidase gene previously published. However, the s imilarity of the non-coding sequences up- and downstream of the open r eading frame was much less, showing only 66% and 50% identity respecti vely. Despite the low degree of similarity between the promotor region of the new gene and the previously published one, the new glucose oxi dase was likewise induced by calcium carbonate. In addition, we showed that this induction occurred on the transcriptional level. Observatio ns concerning the effect of gluconolactone and the levels of glucose-6 -phosphate isomerase upon calcium carbonate induction suggested that t he enhancement of glucose oxidase biosynthesis by calcium carbonate wa s accompanied by a metabolic shift from glycolysis to the pentose phos phate pathway.