| Nostoc flagelliforme, which named ‘Facai’(hair-like vegetable)，is a terrestrialcyanobacterium living in an extreme environment. In China，Nostoc flagelliformemainly thrived in the northwest and northern of arid and semiarid areas. Nostocflagelliforme had the ability of drought-resistant, alkali-resistant, anti-UV and hightemperature tolerance, because of long-term evolution. Thus, Nostoc flagelliforme has aspecial status and ecological significance in China’s western environmental managementand ecological restoration. In order to explore the self-protection mechanism in activeoxygen metabolism and protein, and lipid metabolism of Nostoc flagelliforme under saltstress，the changes and characteristics in antioxidation system，proteins and lipids ofNostoc flagelliforme under salt stress were studied in this thesis. The main results weresummarized as follows.First of all, the experimental results revealed the dynamic change of the reactiveoxygen species (ROS) and the antioxidation system of Nostoc flagelliforme under saltstress. The results indicated that the Nostoc flagelliforme cells content superoxide anionproduction increased with the treatment times prolong and then decreased under NaClwith different concentration. And the superoxide anion production under each NaClconcentration treatment all reached a high-peak concentration (33.31、38.87、44.83、47.94μmol mg-1Dw) in1d. The content of hydrogen peroxide decreased and thenincreased under salt stress of different concentration，and the accumulate contentreached a peak value at15d，and the content were1.87、1.82、1.58and2.05μmol g-1Dw,respectively. The activities of superoxide dismutase (SOD)， catalase (CAT) andascorbate peroxidase (APX) in Nostoc flagelliforme cells increased and then decreasedunder salt stress. In addition, the content of carotenoid increased as the concentration ofNaCl increased, and the maximum carotenoid content in Nostoc flagelliforme cells were1.2326μg/mgDw when the concentration of NaCl was0.8mol L-1.Secondly, to establish an efficient SDS-PAGE system to separate proteins ofNostoc flagelliforme cells, the protein extraction, sample volume and other conditionswere studied. The results showed that total protein was extracted by using acetone asprecipitator, the most appropriate sample volume was45μg, concentration of resolvinggel was12%, when the protein went to the resolving gel, the current was changed to20mA, With Coomassie brilliant blue staining,13clear protein bands appeared with SDS-PAGE. The proteins of Nostoc flagelliforme under salt stress was studied withSDS-PAGE.0.8mol L-1NaCl treated for1day, certain proteins of Nostoc flagelliforme,especially,30.6kDa, were selectively repressed and a few others e.g.,88.76kDa，49kDa，35.89kDa were overproduced. Upon0.8mol L-1NaCl stress for7day and15day,the proteins named58kDa were overproduced. The changes of these proteins mightinfluence the stress resistance of Nostoc flagelliforme.Finally, we studied the changes of the composition and content of glycolipids,phospholipids and fatty acid of Nostoc flagelliforme before and after the salt stress inthe lipid metabolism. The results showed that the content of saturated fatty acids andunsaturated fatty acids took37.23%and22%of Nostoc flagelliforme total fatty acids,respectively. The content of unsaturated fatty acids (C16:1, C18:1) of Nostocflagelliforme increased, while the content of polyunsaturated fatty acids (C18:2)decreased. Unsaturated fatty acids can maintain the relative liquidity of cell membraneto improve the stress resistance of Nostoc flagelliforme. In addition, the phytol thatfound in GC-MS analysis is the component of the chlorophyllous, and the decrease ofthe phytol demonstrated that the chlorophyll can be inhibited by the salt stress. Thecontent of membrane glycolipid and phospholipid decreased as the concentration ofNaCl increased, it could be due to the damage of enzyme involved in lipid synthesisunder salt stress resulting in the disturbance of the biological synthesis of glycolipidsand phospholipids. |
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