A Novel Chitosanase from Penicillium oxalicum M2 for Chitooligosaccharide Production: Purification, Identification...

This study discovered a novel chitosanase from Penicillium oxalicum M2 based on a new screening strategy. An extracellular chitosanase was isolated and purified from the fermentation broth of Penicillium oxalicum M2. A 19.34-fold purification was achieved on a cation exchange column. Using sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, chitosanase was determined at approximately 42 kDa without any subunits. The sequence of peptide in the protein was identified as SALNKNYITNFSTLR by MALTI-TOF/TOF MS. The maximum catalytic activity of the purified enzyme was 60.45 U/mg at the optimum pH and temperature of 5.5 and 60 °C. The enzyme activity held stability in the range of 35-50 °C and pH 3-4.5. Ca²⁺, Mn²⁺, non-ionic surfactants (Tween 20/40/60/80 and Trition X-100) and some common reducing agents (DTT and β-ME) could significantly activate chitosanase. The purified enzyme showed rigorous specificity to chitosan as a substrate. The hydrolysate in the final stage of hydrolysis consisted of chitooligosaccharides with a degree of polymerization ranging from 2 to 5 and without glucosamine or acetylglucosamine. The monomeric enzyme obtained by one-step purification reveal applications potential in sugar industry, and expanded our understanding of the GH75 family chitosanases simultaneously.