The Optimization Research Of Extraction Technology On Pichia Mud

The Pichia expression system has been widely applied in the exogenous gene expression system.Pichia can be used to produce a variety of enzymes in industry.In the process of enzyme production,a large amount of Pichia thallus would also generate,which could make up about 30-40%of the total volume of fermentation.Considering the thick cell walls of pichia,which was difficult for animals to digest,we could not directly use the pichia as animal feed.Putting them into the environment,not only waste resource,but also pollute the environment.The protein content in Pichia cell is very high.It is an effective way to make waste to be useful,and realizing resource recycling by using pichia mud to produce pichia yeast extract further to be used in microbiological culture media material.In this paper,we studied the process conditions about producing yeast extract using pichia mud.The results are as following.(1)The establishment of method to determine yeast extract concentration-refractometer method(2)the optimization of single factor and multi-factor orthogonal experiment.The factors affecting the yield of yeast extract were pH,extraction time,extraction temperature,the concentration of autolyzed accelerator NaCl,yeast slurry and the type and dosage of yeast enzyme.The single factor and multi-factor orthogonal experiment results showed:the quality ratio of pichia mud to sterile water was 1:2,the concentration of NaCl was 3%,the pH value was5.5,temperature was 55,the amount of enzyme was 0.8%,the quality ratio of yeast wall-breaking enzyme to yeast extraction enzyme was 1:2 and extracting time was 8h.In this papper,the process of yeast extraction was studied,by adding additional enzymes to improve the extraction effect of pichia.Consequently,we found that the extraction effect is better when adding the wall enzymes together with the yeast extraction enzyme than to add the single enzyme with the equal concentration.In this experiment,we extracted pichia mud by the autolysis-enzyme combined method.At the same time,the conditions of extraction were studied.Combined with actual production,the optimum extraction conditions were determined finally.Yeast extract yield could reach 35.76%on the optimum condition of bathing in 150rpm and in oven Controlled Crystal Oscillator.(3)In our study,we verified the optimum extraction conditions of pichia mud by pilot test.In the 50L fermentation tank,in the best extraction conditions of 150 rmp extracting 8 h,the yeast extract rate can reach 37.58%,and the total nitrogen content making up 11.36%of the dry weight of the yeast extract,both of which could meet the national premium grade level.