Production of gluconic acid by immobilized in pumice stones mycelium of Aspergillus niger using unconventional oxygenation of culture

Gluconic acid was produced in repeated batch processes with Aspergillus nig er AM-11, immobilized in pumice stone particles using an unconventional oxy genation of culture media based on the addition of H2O2, decomposed by cata lase to O-2 and water. The highest gluconic acid productivity of 8.2 g l(-1 ) h(-1) was reached with 30 g immobilized mycelium per 150 ml, 10% (w/v) gl ucose, at 24 degreesC and pH 6.5, with O-2 at 100% saturation. The immobili zed mycelium was successfully reused up to 8 times in 1-h batches with only a slight loss (11%) of gluconic acid productivity.