| Nostoc sphaeroides is a freshwater filamentous cyanobacteria, mainly distributed in hubei hefeng rice fields, it has very high nutritional value and medicinal value, due to extensive use of pesticide and fertilizer and the influence of human activities, and lead to sharp decline in the production of wild commune.The N.sphaeroides as experimental material was launched long-term semi-continuous outdoor cultivation, and also studies on effects of the different phosphorus concentrations on the growth,the physiological, biochemical and internal structure of N.sphaeroides. In order to outdoor large-scale cultivation of N.sphaeroides to lay a theoretical and experiment foundation, obtain the main results were as follows:In the experiment of different phosphorus concentrations on the growth, physiological and biochemical characteristics of N.sphaeroides, the inoculation concentrations of phosphorus were respectively0,0.087,0.174, 0.696, 1.74mmol/L.The results showed that high phosphorus concentrations(0.696, 1.74 mmol/L) can increase wet and dry weight ratio of N.sphaeroides, inhibit the bursting of N.sphaeroides, higher productivity(the highest productivity(dry weight) was up to 81±13mg·L-1·d-1 in the 0.696mmol/L).And content of polysaccharide and elasticity of N.sphaeroides and phosphorus concentrations were positively correlated, in phosphorus concentration 1.74mmol/L, polysaccharide, group elastic were 42.53%, 31 g respectively. The content of protein and negatively correlated with phosphorus concentration, minimum protein content is 37.83%.In phosphorus concentration of 0 mmol/L, the color of commune group in the twelfth day changed from green to yellow, on the contrary, high concentration group(0.696, 1.74 mmol/L) color remains the same; Compared with N.sphaeroides under high phosphorus concentration, algal filament distribution inside the group in low phosphorus concentrations was more sparse.During June 2013 to April 2014, N.sphaeroides was semi-continuous long-term cultured in 100 L(100 × 10 × 120 cm) and 200 L(20 × 100 × 120 cm) plate type bioreactor in the greenhouse, inoculation density of 5 g/L, 20 g/L and 50 g/L respectively. During the whole cultivation, 12:00 daily records of light intensity changed between 50 to 1000 μmol·m-2·s-1. 15:00 daily records of culturing temperature changed between 0 ℃to 38℃. The highest productivity(dry weight) were respectively 33 mg·L-1·d-1 and 39 mg·L-1·d-1 in the thickness of 10 cm and 20 cm of bioreactor. When inoculation density was at the same time, growth of N.sphaeroides in two kinds of thickness bioreactor were similar. when thickness of bioreactor was at the same time, usually commune productivity were positively correlated with vaccination density. Seasons has much effect on the N.sphaeroides cultivation and content of biochemical component in the greenhouse. During July and August, biomass of N.sphaeroides appeared negative growth, and productivity was-12 mg·L-1·d-1(dry weight). During December the polysaccharide content of the N.sphaeroides was only 6.6% when thick of reactor was the 10 cm and inoculation density was 5g/L, but in December the polysaccharide content of the N.sphaeroides was as high as 40.6% when thick of reactor was the 20 cm and inoculation density was 50 g/L. In July chlorophyll content was only 0.8 mg/L when the reactor was 10 cm thick and vaccination density was 5 g/L, but chlorophyll content was 10.6 mg/L when the thickness of the reactor was 20 cm and vaccination density was 5 g/L in December.During March 2013 to April 2014, N.sphaeroides was semi-continuous long-term cultured in outdoor with 200 L plate type bioreactor(150 ×30 × 60 cm). During the whole cultivation, 12:00 daily records of light intensity changed between 50 to 2000 μmol·m-2·s-1. 15:00 daily records of culturing temperature changed between 0 to ℃40℃, the highest dry weight productivity was 0.023 g·L-1·d-1, the highest fresh weight productivity up to 1.7 g·L-1·d-1. The protein and polysaccharide content of the N.sphaeroides that it was cultured In the winter were the highest, 41.3% and 43.7% respectively. Training to may, 15:00 nutrient solution temperature maintained at 35℃, 12:00 intensity for a long time in the 1500 μmol·m-2·s-1 above, the period of the N.sphaeroides group appear a large number of rupture, no complete group at the end of the training cycle, dry weight productivity was-0.011 g·L-1·d-1. In order to study why the N.sphaeroides not growed after May, N.sphaeroides was cultivated out door by outside shading intensity(intensity as normal light about 40%) and reducing the temperature(temperature control under 28℃). The results showed productivity of N.sphaeroides under sun-shade were respectively 0.023 g·L-1·d-1(dry weight), 0.022 g·L-1·d-1(dry weight). Polysaccharide content of cooling group was higher than that under shading and cooling group shading group, was 46.1%, shading shading protein content was higher than the cooling group, was 34%. And without sun-shade net, When N.sphaeroides was cultivated to 6 days, color of N.sphaeroides in the cool group and the control group changed from green to yellow, to the end of the cycle group all burst. The results show that under the shade the cooling and no cooling N.sphaeroides can normal growth; without sun-shade net, cooling and no cooling N.sphaeroides group would be broken, leading to commune cannot grow. |
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