| Nostoc flagelliforme is a terrestrial cyanobacterium growing in desert steppe of drought and barren,it plays an important role in protecting ecological environment and preventing desertification in arid area. Nostoc flagelliforme provides rich nutritious with multivitamins, amino acids, carbohydrates, protein and Fe,Ca,P,etc. Due to the lack of wild resources, Nostoc flagelliforme cells are studied in artificial liquid for the high cell density cultivation in order to realize the sustainable utilization.In order to improve the cells biomass and exopolysaccharide yield of Nostoc flagelliforme artificial liquid culture,the paper researched to determine the mixed culture of Nostoc flagelliforme cells cultured in high density artificial liquid culture system. Established a culture system of the semi continuous circulation fermentation coupled with membrane separation. And nutritional components of the cultured cells of Nostoc flagelliforme cells were analyzed. The product obtained by spray drying technology of Nostoc flagelliforme cells, provide the basis for the industrial production of Nostoc flagelliforme.Following results were obtained:1、The species and optimum concentration of carbon source, nitrogen source, hormone and light quality were studied by the single factor experiments firstly.And the optimal conditions are optimized by response surface method and the results show that the 2.11 g/L concentration of sucrose, the 3.86 g/L concentration of sodium nitrate,1.74 g/L concentration of NAA are the best culture conditions, and during the cultivation of suitable with red light irradiation, the amount of Nostoc flagelliforme cells are cultured under these conditions was 1.97 g/L, is 3.68 times of blank control group.2、The effects of operation time and operation pressure on membrane flux, effect of dilution rate on cell biomass and exopolysaccharide yield were studied to determine the optimum culture conditions for circulation: the cells were inoculated into 3 L fermentor, circulating fermentation was starting after 3 days, set up the operating pressure of 0.20 MP and the dilution rate is 0.20/h, the cell biomass and extracellular polysaccharide production of Nostoc flagelliforme under this culture conditions were 3.066 g/L and 182.33 mg/L after 10 days.3、The contents of amino acids,Ca,Mg,Cu,Zn,Sr,Fe and Se of cultured and wild Nostoc flagelliforme were determined using HPLC and ICP-OES.The results indicated that the content of total carbohydrate and crude protein accounted for 57.03 mg/L and 26.17%(w/w) in cultured Nostoc flagelliforme, which are higher than the wild Nostoc flagelliforme. the ash and crude fat content is similar in both two,the total content of amino acids of both were 21.99 mg/g and 21.20 mg/g, but the artificial cultivation of Nostoc flagelliforme essential amino acid content is 11.73 mg/g,which were 1.47 times higher than the wild one.The elements of Ca,Mg,Cu,Zn,Sr,Fe,Se in the cultured Nostoc flagelliforme were rich, and Mg,Cu,Zn,Se were 2.9,3.4,3.8,1.6 times higher than the wild one.4 、 The powder yield,content of water were took as indexes,the optimum condition of spray drying of the chestnut powder had been defined by the single factor experiment and L9(34) orthogonal experiment. The results as follows:inlet temperature 180 ℃,the soluble solids 16 Brix?,the drying air quantity 4.5 m2/min,the feeding rate 45×25 m L/h,under these conditions, powder yield was 22.13%(w/w) and water content is 4.87%(w/w), the product quality is well and Nostoc flagelliforme cells have high rate of powder. |
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