**3. Materials and Methods**

#### *3.1. Materials*

*Escherichia coli* TOP10, plasmid pPICZαA, T4 DNA ligase and DNA polymerase were purchased from Takara Biotechnology (Dalian). *Pichia pastoris* X-33 was stored in our laboratory. Beta-chitin was purchased from Sigma (St. Louis, MO, USA). Alpha-chitin was purchased from Seikagaku (Tokyo, Japan) [33]. Colloidal chitin was prepared according to the previously reported method [48]. AMAC, chitin oligosaccharides (GlcNAc) *n* (*n* = 2–6, dimers to hexamers (A2 to A6; A, GlcNAc)) were purchased from Sigma-Aldrich (Munich, Germany). Unless otherwise noted, all reagents were analytical grade. Acetate release was measured using an acetate kit from R-Biopharm (Darmstadt, Germany) [14].
