Abstract

Pectate lyases from Aspergillus spp. are a major kind of industrial pectinases, can improve the surface properties of natural fibers and have promising applications in medicine, food, textile and other industries. Pectate lyases catalyze the eliminative cleavage of de-esterified pectin, which is a major component of the primary cell walls of many higher plants. The Pectate lyase A (PelA) gene without an N-terminal signal peptide sequence from Aspergillus nidulans was recombinantly expressed using Escherichia colias the host strain and pET-20b(+) as expression vector with a pelB N-terminal signal pepetide. PelA biosynthesis reached the maximum production field (450 U ml^-1 medium) at 0.5 mM IPTG, 37°C, 200 rpm, for 2 h and the expressed PelA primarily appeared in extracellular medium. Calcium ion had a more obvious promotion than glycine and SDS to the extracellular enzyme fields, and the C-terminal sequence of Pel A might have an important effect on the transportation through the outer-membrane of E. coli. The time (2 h) of reaching the maximum enzyme at 37°C implied that the PelA expression was very significant to pectate lyase industrial production.

Key words: Characteristics, extracellular expression, pectate lyase A, Aspergillus nidulans, Escherichia coli.