Screening Of Strain Producing Pectinase, Optimizing The Fermentation Conditions And Characteristics Of Pectinase

Pectinase can catalyze the solubilization of pectin. Some microorganisms can produce pectinase under certain conditions. In this study, rotten fruits including Apple, Jujube, and Pear were used as raw materials to screen the Strain producing pectinase highly by plate method. The optimum fermentation conditions were studied by signal factor test and L₁₆(4⁵) design. The application of the pectinase was studied comparing to Pectinex XXL and Pectinex 5XL.The main results are as follows:A strain highly producing pectinase was screened out from rotten Jujube. After identification, it was named as Bacillus cereus.The optimum fermentation conditions were studied by signal factor test and L₁₆(4⁵) design. The result showed that carbon source concentration of fermentation 1%, nitrogen concentration 0.5%, surfactant concentration 0.03%, initial pH of fermentation 4.5 and fermentation temperature 40℃. The production under this condition can reach 10758 u/·mL and the distance from experimental verification test result 10692u/mL was not far. The effects of fermentation temperature, initial pH and nitrogen source concentration on the producing pectinase ability of strain were remarkable as the carbon concentration and surfactant concentration was not.The enzyme activity in the secondary screening was 9632.5u/mL, and the enzyme activity reached 10692u/mL after fermentation optimation increasing by1059.5 u/mL.The optimum reaction temperature and pH of the pectinase were 45℃and 4.0 respectively showing that it was acidic moderate tempreature pectinase. K+,Ca²⁺,Mg2+,Cu2+ were able to enhance the ability of enzyme and the enhancing effect of Ca²⁺ was remarkable. Ag+,Fe2+ could inhibit the ability. The module of enzyme activity and pH (X₁),temperature(X₂),Ca²⁺ concentration (X₃) was as follow: Y=117710.4+13770.4X₁+15053.8X₂+5604.03X₃-5397.5X₁X₂+11580.1X₁X₃-12813.5X₂X₃+18871.5X₁2+114.0X₂2+17671.1X₃2The application of the tested pectinase was studied comparing to Pectinex XXL and Pectinex 5XL. The result showed that the most suitable reaction condition was adition 1.4μL/mL,pH 4.0, reaction temperature 40℃,reaction time80min.The transparency rate of apple juice treated under this condition can reach 91.2% and transparency treated by Pectinex XXL and Pectinex 5XL can reach 86.6%, 89.2% respectively.