SEEDS AS NATURAL MATRICES FOR IMMOBILIZATION OF ASPERGILLUS-NIGER MYCELIUM PRODUCING PECTINASES

A Simple method for the immobilization of Aspergillus niger mycelium p roducing polygalacturonase (PG) and pectinesterase (PE) is described. Fungal conidia were immobilized on wheat, rye, barley, peas, buckwheat and mustards seeds. Spongy mycelia overgrowing the seed surfaces on m ineral medium with pectin produced extracellular PG and PE; the highes t production was reached on the wheat carrier. Some of the variables i nfluencing the enzymatic activity have been optimized. After every 24 h, a culture liquid with 6.8-7.8 U of PG ml(-1) and 7.0-10.1 U of PE m l(-1) was obtained. This procedure also made possible repeated batch e nzyme production and, as many as eight subsequent 24-h batches could b e fermented by using the same carrier without any loss of PG activity. The addition of sodium orthovanadate (1 mmol) into the medium with pe ctin caused a significant increase in PG and PE activity produced by f ree cells of A. niger (by 1.59-fold and 1.67-fold respectively), and o nly 0.47-fold of PG activity in case of the immobilized mycelium.