Purification and characterization of a chitosanase from a nattokinase producing strain Bacillus subtilis TKU007

An extracellular surfactant-stable chitosanase was purified from the culture supernatant of Bacillus subtilis TKU007 with shrimp shell wastes as the sole carbon/nitrogen source. The TKU007 chitosanase was suppressed by the nattokinase, which appeared at the 1st day. The molecular weight of TKU007 chitosanase was approximately 25 and 33 kDa determined by SDS-PAGE and gel filtration, respectively. The optimum pH, optimum temperature, pH stability and thermal stability of TKU007 chitosanase were pH 7, 37 °C, pH 4–9 and 37 °C, respectively. Closest similarity of TKU007 chitosanase was found on the 226th–229th amino acids of B. subtilis ywtD gamma-dl-glutamyl hydrolase. The amino acid sequence of TKU007 nattokinase was similar to that of B. subtilis nattokinase.