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 °C. Its K_m and V_max value were determined to be 1.43 mg/mL and 71.5 μmol/mg·min, respectively. Moreover, PxPME could increase the firmness of pineapple cubes by 114% when combined with CaCl₂. The acidic and mesophilic properties make PxPME a potential candidate for application in the fruit processing.

使用含有柑橘果胶和刚果红的土壤稀释板筛选出一种产生果胶酶的细菌分离物，鉴定为木聚糖类芽孢杆菌SZ 29。果胶甲酯酶基因（Pxpme）被克隆并在大肠杆菌中表达。该基因编码的蛋白质具有 334 个氨基酸，计算分子量为 36.76 kDa。Px PME 与来自胡萝卜属植物的特征性碳水化合物酯酶家族 8 果胶甲酯酶具有 32.4% 的最高同一性。重组的Px PME 显示出对柑橘果胶的比活性为 39.38 U/mg，具有>65% 的甲酯化。Px的最佳 pH 值和温度PME 活性分别为 5.0 和 45°C。其K _m和V _max值分别为1.43 mg/mL 和71.5 μmol/mg·min。此外，Px PME 与 CaCl ₂结合可将菠萝块的硬度提高 114% 。酸性和中温特性使Px PME 成为在水果加工中应用的潜在候选者。