Purification and characterization of the pectin lyase produced by Rhizopus oryzae grown on orange peels

TLDR: Potentiality of Rhizopus oryzae to utilize orange peels under solid state fermentation conditions to produce macerating fluid with high cellulolytic and pectinolytic activities were confirmed in this work.

Abstract: Potentiality of Rhizopus oryzae to utilize orange peels under solid state fermentation conditions to produce macerating fluid with high cellulolytic and pectinolytic activities were confirmed in this work. Addition of NH 4 NO 3 and NH 4 Cl to the fermentation medium improved the macerating potentiality due to an increase in enzyme levels. The pectin lyase (PL) secreted by R. oryzae under these conditions was also purified to electrophoretic homogeneity using ammonium sulphate fractionation and 2-step-column chromatography. The purified PL expressed its maximum activity at 50 °C and pH value of 7.5, showed good stability in the pH range of 7 to 9.5 and its midpoint of thermal inactivation (T m ) was 70 °C after 45 min of exposure. Presence of Ca 2+ enhanced the activity and thermal stability of the purified PL, ions of Mg, Na and K showed a stimulatory effect and ions of Zn, Co, Mn and Hg showed an inhibitory effect on the enzyme activity. K m was calculated to be 3.87 mg/ml, V max was 297 U/ml and the molecular mass was 31 kDa.