Production of pectolytic enzymes by Aspergillvs niger on sucrose

Abstract Simple sugars were used as C‐sources to test whether the chosen Aspergillus niger strain was able to synthesize pectolytic enzymes in a substrate without pectic substances. The most promising results were obtained on commercial sugar (sucrose) which was previously deionized by using a cation exchange resin. Some pectolytic activities such as pectinesterase (PE) and pectin lyase (PL) were similar to those obtained when using a pectin containing substrate. Apple juice depectinizing (AJDA) activity and polygalacturonase (PG) were considerably higher in the sucrose medium. By increasing the sugar concentration from 1.5% to around 15%, the activities increased as follows: AJDA from 15 up to 750 U/ml, PG from 1.8 up to 20 U/ml and PL from 0.14 to 0.65. PE activity was not affected by the sugar concentration. With 14% sugar and other substrate constituents proportionally increased, no benefit was observed with respect to pectolytic activities.