An alkaline pectate lyase D from Dickeya dadantii DCE-01: clone, expression, characterization, and potential application in ramie bio-degumming

Pectinase plays a crucial role in ramie bio-degumming. A pectate lyase gene (pel4J4) from the high-efficiency degumming bacteria Dickeya dadantii DCE-01 of bast fibers was cloned and connected to pET28a, and then the recombinant plasmid was successfully transformed into Escherichia coli BL21(DE3). The pectate lyase (Pel4J4) induced was purified by ultrafiltration and Sephadex G-100 gel chromatography. The enzymatic properties of Pel4J4 were studied in detail. pel4J4 (GenBank accession number: KC900167) had a sequence length of 1179 bp, encoding 392 amino acids. The extracellular pectate lyase activity of pET28a-pel-BL was up to 204.4 IU/mL. The optimal temperature and pH of the purified Pel4J4 were 55celcius and 8.5, respectively. The stable temperature and pH of Pel4J4 activity were 45celcius and 8.5-10.0, respectively. The catalytic activity is Ca2+ dependent and promoted by 1 mmol/L Zn2+, Fe3+, Ca2+, and NH4+, but seriously inhibited by Cu2+ and Pb2+. The optimal substrate is citrus pectin with more than 85% esterification. The heat-resistant alkaline Pel4J4 could strongly degrade natural ramie pectin, indicating a promising application prospect in ramie bio-degumming.