Biochemical and Molecular Characterizations of a Novel pH- and Temperature-Stable Pectate Lyase from Bacillus amyloliquefaciens S6 for Industrial Application

摘要

In this paper, we report cloning of a pectate lyase gene from Bacillus amyloliquefaciens S6 (pelS6), and biochemical characterization of the recombinant pectate lyase. PelS6 was found to be identical with B. subtilis 168 pel enzyme with 100% amino acid sequence homology. Although these two are genetically very close, they are distinctly different in physiology. pelS6 gene encodes a 421-aa protein with a molecular mass of 65,75 kDa. Enzyme activity increased from 12.8 +/- 0.3 to 49.6 +/- 0.4 units/mg after cloning. The relative enzyme activity of the recPel S6 ranged from 80% to 100% at pH between 4 and 14. It was quite stable at different temperature values ranging from 15 to 90 degrees C. The recPEL S6 showed a maximal activity at pH 10 and at 60 degrees C. 0.5 mM of CaCl2 is the most effective metal ion on the recPEL S6 as demonstrated by its increased relative activity with 473%. recPEL S6 remained stable at - 20 degrees C for 18 months. In addition recPEL S6 increased juice clarity. This study introduces a novel bacterial pectate lyase enzyme with its characteristic capability of being highly thermostable, thermotolerant, and active over a wide range of pH, meaning that it can work at both acidic and alkaline environments, which are the most preferred properties in the industry.