Screening Of Pectin-Decomposing Microorganism And Pectinase Production

Pectinases are compound enzymes which can hydrolyse pectin substances. They arewidely used in foods, textile, medicine, paper-making and brewing field and so on. Primarily,they include propectinase, polygalacturonase, pectinesterase and pectinlyase. In this article,we studied the production of pectinase fermented by JXY-17in liquid fermentation and solidstate fermentation, using tobacco stem as raw material. The crude enzyme was used tohydrolyse the pectin in tobacco stem.A fungus JXY-17with high pectinase activity was obtained by repeated screening andidentified as Penicillium sp. Pectinase activity was measured by the method of DNS. Theculture media for production of the pectinase were studied by the method of experiments oforthogonal experiments. The experimental results showed that the order of influential extenton enzyme-production level of Penicillium sp.JXY-17was: pectin>（NH₄）₂SO₄> Tween-80>Zn²⁺. The suitable culture media was composed of pectin1.5%, glucose0.9%,（NH4）2SO42.0%, ZnSO₄·7H₂O0.01%, Tween-800.05%, NaCl0.2%, KH₂PO₄0.03%, K₂HPO₄0.1%,MgSO40.03%, with initial pH of the medium8.0. The inoculum was10%of the culturemedia and fermentation temperature was30℃, the proper volume of the medium placed inthe500mL triangle flask was50mL. After fermentation for108hours, the pectinase enzymeactivity reached1467.29U/mL. The crude enzyme solution produced by Penicilliumsp.JXY-17was used to hydrolyze the tobacco stem powder at50℃for12h, resulting in thetobacco stem powder degraded by29.38%.Production of pectinase from tobacco stem by Penicillium sp.JXY-17in solid statefermentation was carried out also. Monofactorial and orthogonal experiments were adopted inthe optimization of culture media. The experimental results showed that the influential extentof affecting factors on the enzyme production of Penicillium sp.JXY-17was in the order ofwater content>（NH₄）₂SO₄> KH₂PO₄> Tween-80. The culture media for enzyme-productionis optimum as: tobacco stem was used as main material with the ratio of water to tobacco stembeing1∶1.5.The culture medium was supplemented with （NH₄）₂SO₄5.0%, Tween-800.10%,KH₂PO₄0.03%, KH₂PO₄0.2%, with nature pH（4.8）. The inoculum volume was25mL, thetobacco stem in the1000mL triangle flask was50g.When fermentation was carried out at30℃for6days, the highest enzyme activity of pectinase reached8171.35U/g.The pectinases were recovered by salting out with ammonium sulphate and dialyzation.After recovery pectinases, the residues of tobacco stem and the composition of the crudeenzyme solution were analyzed. The pectin was reduced by45%compared with control（tobacco stem）. The yield of the solid residue tobacco stem was about50%, parts of which arecellulose materials then can be recovered by filtration.Tobacco stem powder was hydrolysed by the crude enzyme solution at50℃for12h.The pectin was reduced by17.53%. The results showed that it was technically andeconomically feasible to produce pectinase from tobacco stem by Penicillium sp.JXY-17insolid statefermentation. Using tobacco stem as raw material in solid state fermentation,pectinases were obtained, and lots of included filter of residue tobacco stem which was part of pectins were reduced, filter of residue tobacco stem can used in the tobacco industry.