| Wild Cordyceps sinensis has a reputation of "soft gold".China's Cordyceps resources have been caught in the vicious cirCle of "the less and the more expensive,the more expensive and the more digging".The valuable part of the cordyceps sinensis is the thallus part,producing mycelium through the liquid fermentation,having the advantages of short fermentation cyCle,easy to control,high yield,the proper cost and the great significance.As the government has been strengthening its control on the emissions of industrial waste water,it's environment-friendly to use the nutrients in the waste water to cultivate oil microbes,which can produce high-value oil and turn waste into treasure.The main works of the experiment are as follows:1.Optimizing the method of extracting all the compositions in the Cordyceps,we found that 5%methanol solution can achieve the best extraction,using phenol-sulfuric acid method to analysis polysaccharide content,Cordyceps polysaccharide was collected by alcohol precipitation method,the recyCle rate was 88.1%.2.The original culture medium was optimized,mainly N source optimization,take use of the milk or milk powder instead of acid to hydrolysis casein and corn flour,we found that using milk and milk powder as the nitrogen source improveed the yield of ingredients to a large extent.The optimized post-culture medium content:dilution ratio of water and milk = 2:1,glucose 50 g/L,potassium dihydrogen phosphate 2.5 g/L,magnesium sulfate heptahydrate 0.5 g/L,compound VB 2.5 tablets/L.After 5 days' fermentation,we get biomass 13.61 g/L,adenosine 486.24 mg/100g,guanosine 427.44 mg/100g,uridine 475.62 mg/100g and cordycepin 36.93 mg/100g.3.Carried out the 5 L tank validation test,the final cell dry weight was 11.56 g/L.The highest content of adenosine,guanosine and uridine was 771 mg/100g,859 mg/100g,887 mg/100g.The highest Cordyceps content was 29.59 mg/100g,the highest content of Cordyceps polysaccharide of 23.68%was achieved at 48h,a certain extent of increase was reached compared with the original medium,while N source costs 56.8%lower than the previous.4.The mid-term fed-batch experiment was carried out to control the glucose content at 15 g/L or more,supplemented with C source or both C source and N source,we found that adding carbon and nitrogen at the same time was better than only adding C source in the fermentation mycelium.The highest content of adenosine was 871 mg/L,the highest content of Cordyceps was 46.7 mg/100g.5.Taking use of the Rhodotorula glutinis yeast to ferment waste water which can effectively avoid wastage after fermentation,and the ultimate Rhodotorula yeast biomass was 15.90 g/L,oil production was 3.14 g/L,COD dropped from 38675 mg/L to 16512 mg/L and the removal Rate was 57.3%.6.With cassava ethanol wastewater as the culture medium,the Rhodototula glutinis as the strain,it was first determined that the untreated wastewater would not inhibit the growth of the strain,the highest oil yield was achieved when the initial sugar concentration was 30 g/L.Then we further optimized the medium.The results showed that the best growth rate reached when the C/N was 75.A 5 L tank scale-up test was carried with the optimized culture medium,the final biomass amount was 14.52 g/L,oil yield was 3.27 g/L,COD removal rate reached 67.3%.The feed solution was a 15 g/L dextrose solution.Then feed batch was taken and the results showed that adding only carbon source was better than both of carbon and nitrogen,and an increase by 49.2%was achieved compared with the non-feeding.At the same time,when feeding at 72-84 h,oil yield reached the highest after fermentation,up to 5.50 g/L.7.The main contents in the cassava residue were studied,cellulose,hemicellulose lignin and starch content were 19.87%,5.39%,13.88%and 9.9%respectively,other components are mainly nitrogen-free extract,crude fat,crude protein,water and so on.The pretreatment of cassava residue solution with different solid-liquid ratio was carried out.With the increase of solid-liquid ratio,the sugar content was gradually increased after hydrolysis,and the utilization rate of the residue was about 33%.After direct hydrolysis and zymolysis to the untreated wastewater(containing residue),carbon source which can be used were glucose,xylose,arabinose and glycerol acetic acid,organics can be utilized by the Rhodototula glutinis was about 28 g/L.8.The optimum hydrolysis conditions were reached,the highest oil yield of the Rhodototula glutinis was 2.88 g/L under the condition of 2%H2SO4,55%solid content,121? for 1h.The best COD/N/P content in wastewater was 1500:5:3,the oil yield increased from 2.88 g/L to 3.82 g/L,an increasement of 34.98%was achieved.A 5L tank scale-up test was carried with the optimized culture medium,the oil yield of the optimized wastewater raised from 3.78 g/L to 4.78 g/L,increased by 37.36%.At the same time,the utilization rate of organic matter was studied,which was Glucose>xylose>glycerol. |
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