Screening And Fermentation Of The Strains With High Yield Chitin Deacetylase

This paper is to screen a strain that highly produces chitin deacetylase from the soil of the bank of the Xiang jiang river, and then identify it. We further optimize the culture medium and process conditions by using deep fermentation of the strains for chitin deacetylase; We construct the fermentation dynamic model of chitin deacelation enzyme by studying the experiment of fermentation tank amplification.Five strains which can produce chitin deacetylase from soil of Xiangjiang river side were screened by color reactions of paranitroacetanilide. The strain Al with high productivity was screened through the secondary screening, and the chitin deacetylase showed good ability. On the basis of morphological characteristics and ITS sequence identification, strain A1was identified as Fusarium proliferatum.Studying the fermentation medium components of strain A1through single factor experiment, we obtain the best formula of medium fit for growing the chitin deacetylase strains:lactose as the carbon sources, yeast extract as nitrogen source, ferrous sulfate as the mineral salt, and chitin as the impact factor. And then using these medium components as independent variable and the enzymatic activity of chitin deacetylase as response value, utilizing the Design-Expert7.0software according to the Box-Behnken central composiet principles of design, and applying RSM to optimize the experiment, we obtain the regression equation which can predict the enzyme production of chitin deacetylase: R1=17.41+1.11A+0.78B+1.14C+0.41D+0.32AB+0.40AC-0.064AD-0.017BC+0.68BD-0.081CD-5.28A2-3.32B2-4.00C2-4.02D2. We determine the best fermentation medium level of enzyme production:yeast extract with10.57g/L, lactose with10.65g/L, ferrous sulfate with5.44g/L, chitin with10.30g/L. Compared with single factor experiment, this enzyme activity is increased by1.2times from14.69U/mL to17.62U/mL after optimization.Similarly, Studying the fermentation medium conditions of strain A1by single factor experiment, the results showed that pH, culture temperature, and rotating speed were key factors of the production of enzymes for fermentation. According to the optimizing analysis of Box-Behnken central composiet principles and RSM, we obtain the multiple regression equation that can predict the enzyme production of chitin deacetylase: R1=17.28+0.45A+2.04B+1.45C+0.18AB-0.21AC+0.33BC-3.64A2-3.32B2-3.73C2. We determine the best level of the culture conditions:pH7.06, culture temperature28.96℃, rotating speed183.88r/min. In order to apply for the practical application, the optimal culture conditions be ajusted to pH7.0, culture temperature29℃, rotating speed180r/min.This enzyme yield (17.75U/mL) is increased by1.26times after optimization when compared with single factor experiment whose maximum enzyme activity is14.12U/mLThrough the Logistic model, we established the fermentation model of chitin deacetylase. We laid the technical foundation for the further enlarged production by using the1stOpt software to process the experimental data and model fitting of the experimental data.