Two chitosanases (CHSB1 and CHSB2) were purified from the culture supernatant of Bacillus cereus TKU018 with shrimp shell as the sole carbon/nitrogen source. The molecular masses of CHSB1 and CHSB2 determined by SDS-PAGE were approximately 44 kDa and 22 kDa, respectively. The optimum pH, optimum temperature, pH stability, and thermal stability of CHSB1 and CHSB2 were (pH 5, 60 °C; pH 5-7, <40 °C) and (pH 7, 50 °C; pH 4-7, <50 °C), respectively. CHSB1 and CHSB2 were both inhibited by EDTA and CHSB1 was inhibited completely by 5 mM Zn2+. CHSB1 and CHSB2 degraded chitosan with DD ranging from 60% to 95%, but did not degrade chitin. The most susceptible substrate was 60% deacetylated chitosan. Furthermore, TKU018 culture supernatant (1.5% SPP) incubated for 3-4 days has 75% relative antioxidant activity (DPPH scavenging ability). With this method, we have shown that shellfish wastes may have a great potential for the production of bioactive materials.
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