Study On Producing Feedstuff Protein By Mixed Microorganisms Fermented Okara And Beancurd Processing Wastewater

With the fast development of industry and agriculture,people pay more attention to environment around us,thus it becomes the most important research areas to produce useful products for human and environment,using waste residue and waste water from industry and agriculture.The bean residue and beancurd processing wastewater are the byproducts of processing bean curd.The deep exploitation of these byproducts,not only an effective way to solove the shortage of protein feedstuff,and an useful way to protect the environment. Reduced fiber content and increased protein content of bean residue were studied by microbial fermentation. Bean curd processing wastewater was used to produce sing cell protein by liquid state fermentation. And the capacity of the growth of Streptococcus thermophilius was studied in this paper.Selection of strains with high-efficiency cellulose-degrading was stuied. Strains of microorganism which can grow in CMCNa as unique carbon source were isolated.Then,by using congo red cellulose identification culture medium and determining the production of the CMCase, we seleced six strains which had large D/d value(ratio of diameter of clearing zones and colony)and had high production of cellulose. These strains are F1, F2, F3, F5, F6 and F8. They are yielding of CMCase activity has reached 781U/mL.The most suitable growth condition of strains were studied by orthogonal design.The strains for the okara solid state fermentation were researched.The results showed that crude protein in the bean residue could increase by microbial fermentation.We studied the crude protein content variation after singl fungal fermention and mixed fungal fermention.Then,the strains of F2,F6 and Geotrichum candidum are ascertained for mixed okara-fermention.The result of fermention experiment indicate the crude protein increase by 11.96% from 14.80% to 26.76%.The condition of mix fungl co-fermentation were optimized.The results showed that urea and ammonium sulfate were suitable to be used as nitrogen souree by measuring the true protein product after fermentation.The amount of urea is 1.5% and ammonium sulfate is 2%. The fermentation condition of producing high content of protein from the bean residue was researched by a series of single factors and orthogonal design tests. The experimeng results show that the optimal conditions are:the proportion of F2, F6 and Geotrichum candidum is 1:1:2, water initialization content of bean residue culture media is 75%, inoculum amount is 10%, the solid state fermentation temperature is 30℃,the solid state fermentation time is 3.5d.Under this contion,the ture protein content is increased from 13.72% to 22.28%,the rate of increase of ture protein is 62.27%.The producing of single cell protein and the cultivating Streptococcus thermophilius were researched using beancurd processing wastewater by the liquid fermentation. The results showed that the wastewater are rich nutrition and suitable to cultivate Geotrichum candidum and Streptococcus thermophilius.The yield of dry-cell biomass was 10.788g/L,when the inoculum amount was 3%,the shaking speed was 120r/min, the fermentation temperature was 28℃,the liquid state fermentation time was 48h.Cell growth of Streptococcus thermophilius was studied by using colony-counting method.The experiment indicate that the bean curd processing wastewater was a good nutrient medium for Streptococcus thermophilius when adding 1% glucose to the wastewater.The result showed that the population of Streptococcus thermophilius can reach as high as 7.9x10',when the inoculum amount is 5%,the fermentation temperature is 37℃, the shaking speed is 220r/min, the fermentation time is 48h.