Isolation of a Filamentous Fugal Strain and Enzyme Property of Its Extra Cellular Pectinase
In the present study,soil samples in plum rain season were collected and micro-organisms producing pectinase were isolated on medium containing orange peel powder as sole carbon source.Twelve bacteria strains with various shapes were isolated,but none of them showed extra cellular pectinase activity under liquid cultivation.Five filamentous fugal strains were isolated,and one of them(XYYWZSP3)showed extra cellular pectinase activity of(0.39±0.01)U/mL in the culture broth.The hypha of XYYWZSP3 was white on Czapek medium plate,and the colony was loosening,with no pigment produced.The optimal pH and temperature of XYYWZSP3 pectinase were pH 4.5 and 55 ℃ respectively.After incubation at pH 3.5 to 7.0(at 25 ℃)for 24 hours,the residual pectinase activity of XYYWZSP3 was higher than 90％.The XYYWZSP3 pectinase was stable at 30 ℃,and gradually lost activity as the increment of incubation temperature.After incubation at 50 ℃ for one hour,the residual enzyme activity of XYYWZSP3 pectinase was(23.30±1.83)％.Ca2+ at 1 mmol/L did not affect the enzyme activity,but Ca2+at 5.0 mmol/L reduced the enzyme activity to(45.47±2.74)％.K+、Mg2+、Li+and Na+at 1.0,2.5 and 5.0 mmol/L did not affect the enzyme activity.XYYWZSP3 pectinase functioned well in banana juice production;it increased the content of reducing material by(47.69±2.12)％ and increased the yield by(15.66±1.12)％.Thus,XYYWZSP3 pectinase showed potential in fruit juice production.
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