Research On Production Of Protein From Corn Waste By Aspergillus Niger And Saccharomyces Cerevisiae

Corn production in China has been in the forefront of the world,with the rapid development of corn processing industry,a great deal of wastes is generated.According to statistics,the production of corn stalk is 243 million tons per year in our country,but the amount of wastewater discharged is countless.Random emission or improper disposal of these wastes has polluted the environment to great degree.Currently,microbial recycling is an effective way to dispose corn waste and reduce environmental pollution.This topic is based on corn in-depth processing wastewater and corn stalk,producing cell protein(CP)by microbial conversion of the above wastes.This method not only effectively utilizes the rich organic nutrients in the waste and creates additional economic value,but also reduces the environmental pollution of waste.First of all,the main ingredients and characteristics of the experimental materials were analyzed in this study,and Aspergillus niger and Saccharomyces cerevisiae were selected as fermentation strains through the growth experiment of strains.There is no antagonism between these two strains in mixed culture,and it is suitable for mixed fermentation system.Through the experiment of mixed strains fermentation,we found that in the condition of the mixing ratio of corn in-depth processing wastewater and corn stalk was 2:3,and the granularity of corn stalk was 0.1 cm-1 cm,the protamine content and cellulose degradation rate in fermentation products have the optimum value.With the protamine content in fermentation products as indicators,we optimized the process conditions of protein production.In the investigation of the influence of various factors on protein production,we obtained the optimum values of each factor: the temperature was 28?,the proportion of Saccharomyces cerevisiae and Aspergillus niger was 4:1,the ratio of solution to solid was 0.9:1,the loding capacity was 20 g/bottle,and the inoculum size was 2%.We screened out three significant factors affecting protein production: the t emperature,ratio of solution to solid and mixing ratio of bacterias,through the Plackett-Burman(PB)design.The center level of the optimized factors was determined by the steepest climbing test,which was taken as the central point of the response surface test.We optimized the significant factors affecting protein production by Central Composite Design(CCD),and the protein production reached maximum at the optimum fermentation conditions of temperature 28.4?,ratio of solution to solid 0.96:1,proportion of Saccharomyces cerevisiae and Aspergillus niger 4.56:1,inoculum size 2%,and loding capacity 20 g/bottle.The results of the verification test showed that the protamine content in fermentation products was 20.13%,which was basically consistent with the theoretical value of 20.76%.The fermentation product is yellowish-brown in appearance after drying,and gives off a faint aroma of wine from the original pungent odor.Moreover,the fermentation product is rich in nutrients,especially proteins and amino acids.