Purification of chitinase/chitosanase from Bacillus cereus and discovery of an enzyme inhibitor

A chitinase and a chitosanase were induced from a squid pen powder (SPP)-containing medium of Bacillus cereus TKU030 and purified by precipitation with ammonium sulphate and combined column chromatography. The purified chitinase and chitosanase exhibited optimum activity at 60 °C, pH 5–6 and 40 °C, pH 4, respectively. The chitinase and chitosanase were stable at 25–60 °C, pH 4–7 and 25–50 °C, pH 3–7, respectively. The chitinase and chitosanase showed the highest activity toward β-chitin and 60% DD chitosan, respectively. The chitinase was significantly inhibited by Mn2+ and EDTA but activated by Cu2+, Fe2+ and Ca2+. The chitosanase was significantly inhibited by Cu2+, Fe2+, Zn2+, Mn2+ and EDTA. The chitinase showed high stability in the presence of various surfactants, such as SDS, Tween 20, Tween 40 and Triton X-100. In contrast, these surfactants were inhibitors of the chitosanase. The chitinase and chitosanase were also inhibited by TKUPSP017, a small synthetic boron-containing molecule with a BF3K side-chain. However, TKUPSP017 enhanced the growth of B. cereus TKU030 in SPP-containing medium.