Solid Fermentation Using Raw Material For A Marine Aspergillus Niger And The Immobilization Of Cellulase

Cellulase is not a single enzyme,but a complex enzyme system.It plays a vital role in the hydrolysis of cellulose.Based on the liquid state fermentation and solid state fermentation of Aspergillus niger,this paper focuses on the research of solid fermentation using raw material,optimizes the culture conditions by the response surface method.After that,the amplification process of solid fermentation using raw material was studied.Then we research on the immobilization of cellulase.Finally got the following conclusions:(1)Under the raw material conditions,the solid-state fermentation conditions for marine Aspergillus niger was optimized.The basic culture medium for Aspergillus niger fermentation was:bran as a carbon source,NH4CI as a nitrogen source,and add KH2PO4.Through the single factor analysis and response surface analysis,the best culture conditions to produce cellulase were finally obtained:bran 20 g,corn straw powder 5 g,straw powder 5 g,NH4Cl 0.8 g/L,FeSO4 0.01 g/L,KH2PO4 0.3 g/L,and glucose 9.16 g/L.With a salinity of 10%,deionized water 60 mL,inoculum size 34.89%,and initial pH 5.0,the medium was cultured at 30? for 5 days.The enzyme activity of filter paper optimized after this experiment reached 12.29 U/g.(2)In this paper,the optimized culture conditions were applied to the amplification experiment,with a magnification of 30 times.First,the response medium was used to optimize the raw media formulation and culture conditions for preliminary testing.In the scale-up experiment,it was found that the fermentation period was slightly prolonged,and the highest enzyme activity was reached on the 7th day of fermentation,and the highest enzyme activity was 9.05 U/g.After a single factor analysis of factors such as fermentation temperature,air humidity,material turnover,stack thickness,it was found that through repeated agitation,increase the early fermentation temperature to 35 ?,reduce the stack thickness to 4 cm,and the air humidity was constant at 65%,can effectively inhibit bacterial contamination and increase the enzymatic activity of cellulase.(3)The method of immobilizing cellulase was studied.The immobilized cellulase was prepared by using sodium alginate,chitosan and agarose as carriers,and the carboxymethyl cellulose enzymatic activity(CMC)to three kinds of immobilized enzymes was determined.In comparison,alginate-immobilized cellulase has the highest enzyme activity.After analyzing several factors in the process of immobilization,found the optimal method is to add 40 mg/mL of sodium alginate to the crude enzyme solution at pH 5.The crosslinker glutaraldehyde concentration is 0.3%and the immobilization time is 8 h.The above work,especially the application of raw materials,provides an effective way to simplify the production of cellulase by fermentation of marine Aspergillus niger and increase cellulase enzyme activity,also provides important data and methods for the engineering production of cellulase.