OPTIMIZATION OF PECTINOLYTIC ENZYMES BIOSYNTHESIS BY IMMOBILIZED MYCELIUM OF ASPERGILLUS-NIGER-71

Conidia of Aspergillus niger 71 mutant producing polygalacturonase (PG) and pectinesterase (PE) were immobilized in sintered glass Raschig rings (RR), polyurethane foam (PF) or pumice stones (PS). However, A. niger mycelium immobilized on these carriers and grown on the medium with wheat bran extract was partially released to the medium. Controlled growth and a good stability of A. niger 71 mycelium were obtained using PS as carrier and a simple mineral medium containing 1% of apple pectin. This procedure made possible repeated production of batch PG. Subsequent thirty 24-h batches could be fermented by using the same carrier at a small loss of PG activity. Some culture conditions, eg., pH, medium temperature, agitation speed, the amount of pumice stones and apple pectin were optimized to improve the growth and enzyme biosynthesis by immobilized mycelium of A. niger 71.