Mutation Of Aureobasidium Pullulans And Study On The By-products Of The Resource-based Potato Starch Industry

With the rapid economic development,the potato processing industry is about to enter a new stage of development.However,in the potato starch industry and in-depth processing industry,by-products such as potato potato residue juice have become obstacles and bottlenecks restricting the rapid development of such processing industries.The main reason is that the potato potato residue contains some substances that are difficult to use directly.Direct processing The utilization cost is too high,and the juice water contains a large number of microorganisms.If it is discharged directly without treatment,it will cause serious environmental pollution.This topic utilizes Aureobasidium pullulans for fermentation and utilization,which can transform potato starch processing by-products into pullulan polysaccharides,cell proteins and other economic effect products,so that potato resources can be fully utilized,and fundamentally effectively solve the waste discharge of potato industry.Problems can also increase the economic benefits of the potato processing industry.This experiment first studies the biological properties and functions of the starting strain Aureobasidium pullulans HIT-L5^T,mainly including the colony and cell morphological characteristics of the strain HIT-L5^T,as well as the sugar-producing performance research,to prepare for the basis of mutation breeding.The polymorphic changes in the cell growth of Aureobasidium pullulans HIT-L5^Twere studied,and the morphological changes of plate colonies were observed;fermentation experiments were conducted and it was found that the amount of pullulan produced by HIT-L5^T was the highest when the fermentation culture time was 5 days.It was 13.24g/L,but the fermentation pigment was black,and the initial fermentation time after mutagenesis was determined to be 5 days.At the same time,the growth curve of strain HIT-L5^T was drawn by hemocytometer counting method.The starting strain HIT-L5^T was mutagenized by using two methods of ultraviolet and nitrous acid mutagenesis.After two screenings,the mutant strain HIT-L3^N was finally obtained.The polysaccharide yield was increased by 50.60%compared with the starting strain,and the fermentation pigment production was significantly reduced.It is brownish yellow.A genetic stability test was carried out on the mutagenic strain HIT-L3^N,which was continuously subcultured for 10 generations,the polysaccharide yield was 18.95-20.18g/L,the final color of the fermentation broth was brownish yellow,and the final p H value was 3.3-3.7,indicating that the mutant strain HIT-L3^Nnature function is stable.The fermentation and sugar production conditions of the mutant strain HIT-L3^N were optimized.Based on five factors,fermentation time,fermentation temperature,strain inoculation amount,rotation speed,and initial p H were further optimized,and the optimal fermentation conditions were 5 d,28?,4%,180rpm,p H 7.Then,the mutant strain HIT-L3^N was combined with the original potato potato juice juice water mixed fermentation system to conduct a fermentation experiment.The experiment showed that after adding HIT-L3^N,the content of cellular protein in the fermentation product increased by 3.85%compared with the original fermentation system The COD degradation efficiency increased by 14.31%,which was 1.36 times and 1.32 times of that without HIT-L3^N.Therefore,Aureobasidium pullulans HIT-L3^N can be used in the potato starch production industry to solve industrial by-product pollution and its resource utilization.This subject will provide basic research data for the mutation breeding of Aureobasidium pullulans and practical industrial applications.