| Chinese corn stalks are rich in output,with an annual output of 200 million tons.Most of the corn stalks has not been effectively utilized,and the bio-feed product by corn stalks is a economic-effective means of its utilization.This method can solve the problem of difficult utilization and low utilization rate of corn straw,it also can improve the environment and improve the economic value of feed.In this study,corn stalks were used as raw materials and were pre-treated by Instant Catapult Steam Explosion(ICSE)to optimize the screening of high-protein strains for feed production,optimize the production process of feed.It can promote the conversion of corn stalks into biological feed which promotes the industrialization movement,aims to produce three high-value biological feeds.In this paper,the single cell protein feed was produced by adding Candida utilis to the corn stalk hydrolysate after ICSE pretreatment.The components of the corn stalk,ICSE pretreated corn stalk and ICSE pretreated corn stalk after hydrolyzation were analyzed.The results showed that compared with untreated corn stalks by 2.0Mpa,150s ICSE pretreated corn stalks:hemicellulose decreased by 85.7%,cellulose decreased by 4.6%,and lignin decreased by 13.8%.The results showed that decreased 99%of vomiting toxin(DON),aflatoxin B1(AFB1)and zearalenone(F-2),starch content decreased by 25%,crude protein,crude fat and mineral elements did not change significantly.ICSE pretreatment reduced aspartic acid,arginine and lysine in corn stalks by 44.7%,72.7%and 76%,respectively;the total amount of 17 amino acids decreased from 4.03g/100g to 3.63g/100g.By single factor optimization experiment on hydrolysis conditions of corn stalks pretreated by ICSE,we screening optimal hydrolysis conditions of corn stalks.The conditions were cellulase 15 FPU/g,xylanase 3000 U/g,ratio of material to water 1:7,and hydrolysis time was 72 h.Under this condition,100 g of corn stalks was hydrolyzed to produce 35.7 g of sugar.Four strains of Candida utilis were screened for growth performance of xylose and cellobiose,and a strain of Candida utilis BNCC 336517 which can efficiently degrade xylose and cellobiose.The degradation rate of xylose in the medium with sugar as the sole carbon source reached 42%in 48h,and showed good performance in the medium with cellobiose as the sole carbon source.Degradation of cellobiose in fermentation for 24h.The rate reached 95%.Then,the strain of Candida utilis BNCC 336517 was subjected to the tolerance acclimation experiment of corn stalk hydrolysate.The strain of Candida utilis BNCC 336517 can grow in 100%complete hydrolyzate after acclimation,and the growth performance is good.Then the fermentation conditions of the strain Candida utilis BNCC 336517 in corn stalk hydrolysate were optimized.When the corn stover hydrolysate was filtered and sterilized by filtration,and the amount of(NH4)2SO4 was 5g/L,maximum bacterial volume could be obtained after 24 hours of fermentation.The amount of the cells was 2.08 X 108one/mL.The nutrients of the finished single-cell protein feed were tested.The dry weight of the cells reached 14g/L,the crude protein was 46.8%,the crude fat was 8.08%,the crude ash was 5.27%,the P content was 0.46%,and the Ca content was 0.06%.It is feasible to produce single-cell protein feed by corn stalk after ICSE pretreatment.The product with rich nutrient content,has market promotion potential and certain economic value.By optimizing the Instant Catapult Steam Explosion(ICSE)pretreatment of the corn stalk synchronous saccharification and fermentation(SSF)process,the efficiency and feasibility of transforming the corn stalk into the bio-true protein feed process was improved.The Candida utilis BNCC 336517 was cultured using synthetic medium and corn stalk hydrolysate.The effects of simple enzymatic hydrolysis and simultaneous enzymatic hydrolysis on the sugar conversion rate of straw pretreated by instantaneous catapult steam explosion were compared.The orthogonal test was further designed to obtain the optimal conditions for the transformation of corn stalk into true protein.Candida utilis can efficiently utilize cellobiose at 37?,simple enzymolysis 100g,instantaneous catapult steam explosion pretreatment of corn stalk can produce 32.16g total sugar,dry matter degradation rate after simultaneous enzymatic hydrolysis is 51.61%.the utilization rate was 84.1%;the three-factor and three-level orthogonal experiment results under the same temperature conditions:the ratio of material to water 1:7,cellulase complex 20 FPU,1%(NH4)2SO4.The true protein content of the product after fermentation for 96 h was 14.66%.The optimal simultaneous enzymatic hydrolysis conditions of Candida utilis were obtained,and the conversion of corn stalks to produce biological feed under such conditions was economically feasible.The dry yellow corn stalks were pretreated by instantaneous catapult steam explosion(ICSE)and then corn stalks micro-storage was produced.The changes of nutrient composition and the change of ruminal material digestibility of dairy cows were investigated.ICSE pretreatment of dry yellow corn stalks with 1.2Mpa,200s;1.8Mpa,200s;2.0Mpa,150s,anaerobic micro-storage of lactic acid bacteria for 60 days;Detection and comparative analysis of crude nutrients,amino acid composition and mycotoxin content in micro-storage products.The micro-storage product was used to evaluate the disappearance rate of rumen dry matter in dairy cows,and to provide reference for the application and promotion of dry yellow corn straw micro-storage products in ruminant breeding process.The quality of micro-storage was the best after 1.8Mpa,200s pretreatment,its pH value 4.45,water content 54%,crude protein 10.85%,crude fat 8.12%,crude fiber 27.73%,NDF content 44.5%,ADF 35.53%,total amino acid 3.91%.The rumen disappearance rate test showed that the crude protein disappearance rate was 77.1%,the NDF disappearance rate was 22.8%,and the DM disappearance rate was 51.7%.The mycotoxin content after micro-storage is within the national safety standards.After 1.8Mpa,200s pretreatment,micro-storage dry yellow corn straw significantly improved the quality of corn stalks feed,and has certain application and promotion potential in ruminant culture. |
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