Expression and thermostability of Paenibacillus campinasensis BL11 pectate lyase and its applications in bast fibre processing

摘要

An open reading frame (ORF) with 963 nucleotides from Paenibacillus campinasensis BL11 was cloned and expressed in Escherichia coli. It encodes a pectate lyase (EC 4.2.2.2) of 35.6 kDa, denominated Pel-BL11. The recombinant Pel-BL11 was fused with His-tag and purified. An optimal activity of 1623 IU mg-1 was exhibited at 50 degrees C, pH 10. Significant activities of Pel-BL11 are demonstrated between 40 and 70 degrees C and from a pH of 7-11. The observed half-lives are 103 min at 70 degrees C and 288 min at 40 degrees C. Compared to other published acid and alkaline pectate lyases, Pel-BL11 demonstrated exceptional thermostability and wider pH adaptability. Temperature effects on the cleavage of the pectate alpha-1,4-glycosidic bond by Pel-BL11 were examined. Continuous cleavage occurred for the first 3 h at 30 and 50 degrees C. However, at 70 degrees C, the majority of the cleavage occurred during the first 10 min. Weight loss in gampi and paper mulberry fibres after enzyme treatment validate the potential of this treatment in fibre degumming.