Screening Strains And Optimizing Conditions Of Astragalus Residuse Solid-State Fermentation

Astragalus residue is produced after the extraction of Astragalus polysaccharides (APS). In the industrial production, most of the extract methods of APS still stay in water extraction and alcohol precipitation. This method also produces a large number of residue and other pharmaceutical ingredients of Astragalus were remained in the residue. So the Astragalus residue can strengthen the animal body’s immune function and promote the body metabolism. Making bioconversion of Astragalus residue by using solid-state fermentation technology can make full development of Astragalus residue and improve the level of comprehensive utilization of it. It makes the second efficient utilization of resources.Firstly, the composition of Astragalus residue was analyzed. The result indicated that crude fiber content, mannitol content, soluble sugar content, reducing sugar content, fat content, protein content, crude ash content, moisture content of Astragalus residue were amounted to42.74%±0.08%,1.15%±0.01%,12.36%±0.09%,3.83%±0.06%,0.50%±0.01%,8.92%±0.08%.,4.16%±0.14%,5.29%±0.27%, respectively.Secondly, the strain of solid-state fermentation was screened. Five strains of cordyceps fungi were selected as solid-state fermentation’s strains and their growth curve were measured. The best culture time of Paecilomyces cicadae ZZYC, China Paecilomyces DCXC, Paecilomyces gunnii ZZY, Paecilomyces militaris ZZYZB, Paecilomyces militaris ZZYYS were3days,3days,3days,3days and5days, respectively. The solid-state fermentation’s strains were screened with the crude fiber degradation rate and the mannitol content in the fermented product after solid-state fermentation. From the result of strain screening experiment, we can make sure that using the Paecilomyces bainier as fermentation strain.The condition of solid-state fermentation was optimized after determining the fermentation strains. The single factor optimization experiment was carried out from fermentation time, inoculum size, initial pH value of fermentation culture medium, fermentation substrate thickness. From the crude fiber degradation rate and the mannitol content in the fermented product, we can conclude that fermentation time, inoculum size, initial pH value of fermentation culture medium, fermentation substrate thickness were25d,20%, nature pH value,1.0cm, respectively. The orthogonal design determined the optimal solid-state fermentation process that fermentation time, inoculum size, initial pH value of fermentation culture medium, fermentation substrate thickness were25d,20%, nature pH value,1.0cm, respectively. The results of orthogonal verification test showed that the crude fiber degradation rate was23.23%±0.19%and the mannitol content in the fermented product after solid-state fermentation was2.46%±0.03%. The mannitol content increased by113.90%after solid-state fermentation.Finally, the pilot scale cultivation of solid-state fermentation was studied. The raditional shallow tray fermentation was used in the pilot scale cultivation of solid-state fermentation. The result showed that it wasn’t suitable for this experiment. After experimental exploration, the new cultivation box of fermentation was invented. The pilot scale cultivation of solid-state fermentation was completed smoothly. With the cultivation box whose specification is280x180x120mm, about40kg Astragalus residue was used. The fermented product was weighed28kg. The yield of fermented product was70%.