Purification and characterization of a pectin lyase produced by Geobacillus stearothermophilus Ah22 and its application in fruit juice production

Abstract

Extracellular pectin lyase (PL) (EC 4.2.2.10) was produced by Geobacillus stearothermophilus Ah22 in solid state fermentation. The PL enzyme was purified 40.8-fold by DEAE-cellulose anion exchange column chromatography and characterized. The molecular weight of the enzyme was determined as 36 kDa by Sephadex G-100 gel filtration chromatography. Purification of the enzyme was verified by SDS-PAGE. The optimum pH and temperature of the enzyme were determined as pH 6.0 and 60°C, respectively. The PL was mostly stable at 40°C. Its activity deceased by 50% after 2 h at 60°C and by 60% after 6 h at 50°C. The Vmax and Km were calculated as 0.47 mg/mL and 355.3 μmol/L·min, respectively. The presence of 10 mM Ca2+, Cu2+, Mn2+, Mg2+, Zn2+, Hg2+, Fe2+ and EDTA, l-cysteine and ascorbic acid significantly enhanced enzyme activity. The purified PL enzyme was used in the production of fruit juices; yields of fruits juice improved significantly compared with controls.