초록
<P><B>Abstract</B></P> <P>Medium compositions for a heat-tolerant acidic pectinase production from <I>Bacillus</I> sp. ZJ1407 were optimized via response surface methodology (RSM) and its enzymatic properties were investigated. A 2-level factorial design was used to estimate the main effect of factors, and to screen the significant factors. A central composite design was used to find out the optimal concentrations of screened key factors. Lactose, tryptone and (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> were found to have a significant influence on the pectinase activity (<I>p <</I> 0.05). The optimal medium compositions were as follows: lactose 44.8g/l, tyrptone 30.9g/l, (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> 1.35g/l, MnSO<SUB>4</SUB>·H<SUB>2</SUB>O 0.2g/l, MgSO<SUB>4</SUB> 0.4g/l and NaCl 3.5g/l. Pectinase was purified to homogeneity by ammonium sulphate precipitation, DEAE-cellulose ion-exchange chromatography and Sephadex G-100 size-exclusion chromatography. The molecular weight of the purified pectinase determined by SDS-PAGE was about 23kDa, and its final specific activity was 110.47U/mg. Its optimal temperature and pH were 37°C and 5.0, respectively. Pectinase was very stable within a pH range of 3.0–5.0, and showed a high thermo-stability at 80 and 90°C. Ba<SUP>2+</SUP> could significantly promote the activity of pectinase, and Mn<SUP>2+</SUP> heavily inhibited its activity. This study provides new insight into the future development and use of pectinase from <I>Bacillus</I> sp. ZJ1407.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Production conditions of the heat-tolerant acidic pectinase were optimized by RSM. </LI> <LI> The heat-tolerant acidic pectinase was purified to homogeneity. </LI> <LI> Enzymatic properties of the heat-tolerant acidic were investigated in detail. </LI> <LI> This study provides new insight into the future development and use of acidic pectinase. </LI> </UL> </P>