Studies On Structural And Physiological Characteristics Of Nostoc Sphaeroides On Different CO₂ Concentration And Mass Culture Of N. Sphaeroides

Nostoc sphaeroides is an edible cyanobacteria, which has a high nutritional value and medicinal value. It is now mostly living in the rice fields of Hefeng county, Hubei provice, China. But the annual yield of Nostoc sphaeroides is continuously fewer and fewer because of the sharp change of the environment, which is much less than the market requirements. Therefore, more and more researchers had started the research which aimed at the artificial culture of Nostoc sphaeroides indoors or outdoors. On the area of Controlled Ecological Life in Control System?CELSS?, researchers are closely keeping attention to it, because Nostoc sphaeroides is not only a nutritional food, but also a algae which can remove the carbon dioxide and produce oxygen as well as. And it can accumulate large amounts of biomass in a short time but it occupied much less than traditional higher plants.The Nostoc sphaeroides is cultured at three different CO₂ concentrations?380 ppm?900 ppm ? 1500 ppm?, and it measured by three aspects: growth ?physiology ?and photosynthesis. The results that I obtained are as follows:?1?Firstly, It was found that as the CO₂ concentrations getting higher, the fresh weight and the dry weight of Nostoc sphaeroides are increasing faster. After a period of cultivation, fresh weight of the group of CO₂ concentration 1500 ppm is 1.63 times than the group of CO₂ concentration 380 ppm and 1.28 times than the group of CO₂ concentration 900 ppm;dry weight of CO₂ concentration 1500 ppm is 3.05 times than the group of CO₂ concentration 380 ppm and 1.47 times than the group of CO₂ concentration900 ppm. So is the ratio of dry weight and fresh weight, the group of CO₂ concentration1500 ppm has the highest ratio 1.57, which indicating that the elevated CO₂ concentrations is good for the accumlation of dry matter. Meanwhile, under the condition of elevated CO₂ concentrations, the Nostoc sphaeroides has a relatively smaller averageparticle diameter and a better flexibility.?2?Secondly, Through the measure of protein content and soluble polysaccharide content, it was found that as the as the CO₂ concentrations getting higher, getting higher,the protein content and soluble polysaccharide content also increased, so does the activity of antioxidant enzyme, which indicating elevated CO₂ concentrations is good for improving the antioxidant capacity of Nostoc sphaeroides.?3? At the end of a period of culture, the photosynthetic characteristics were determined as well. It was found that as the CO₂ concentrations getting higher, the chlorophyll content of Nostoc sphaeroides has increased too, so does the Fv/Fm?r ETRm and Ik, it showed that as the CO₂ concentrations increased, the photosynthetic capacity of Nostoc sphaeroides also enhanced.?4?Design a simple and efficient plate photobioreactor, which was applied to the experiment, and when the N.sphaeroides were cultured by this photobioreactor in a constant temperature room, it was found that fresh weight of N.sphaeroides continued to increase, from December 31, 2015 to March 7, 2016, it maintain a relatively stable growth rate,from 20.04 g/L to 117.64 g/L, indicating that the plate photobioreactoris a effective way to train a large number of N.sphaeroides.