Zhong_2020_Protein.Expr.Purif_179_105798

A pectinase-producing bacterial isolate, identified as Paenibacillus xylanexedens SZ 29, was screened by using the soil dilution plate with citrus pectin and congo red. A pectin methylesterase gene (Pxpme) was cloned and expressed in Escherichia coli. The gene coded for a protein with 334 amino acids and a calculated molecular mass of 36.76 kDa. PxPME showed the highest identity of 32.4% with the characterized carbohydrate esterase family 8 pectin methylesterase from Daucus carota. The recombined PxPME showed a specific activity with 39.38 U/mg against citrus pectin with >65% methylesterification. The optimal pH and temperature for PxPME activity were 5.0 and 45 degreeC. Its K(m) and V(max) value were determined to be 1.43 mg/mL and 71.5 mol/mg.min, respectively. Moreover, PxPME could increase the firmness of pineapple cubes by 114% when combined with CaCl(2). The acidic and mesophilic properties make PxPME a potential candidate for application in the fruit processing.