Metabolism-release Mechanism Of Cyanobacteria Under Allelopathic Effect

With the rapid development of industry in new century, environmental pollution is increasing, and lake-type eutrophication of drinking water sources is widespread. Algae bloom situation is still pessimistic, the outbreak is faster, the duration is longer and the impact is larger.In this paper, Microcystis aeruginosa (M) and Pseudanabaena sp. (P1 and P2) were used to study,including algae-algae mixed culture under different initial concentrations, filtrate culture and adding odorous substances culture.Many researches have pointed out Microcystis aeruginosa and Pseudanabaena are the dominant species of algae bloom, and the highest concentration of Microcystis aeruginosa and Pseudanabaena in water are 10//L and 101V/L, respectively. In natural water, odorous compounds produced by Microcystis aeruginosa and Pseudanabaena are mainly β-cyclocitral and 2-methylisoborneol camphol (2-MIB), respectively. Other odor compounds produced by Microcystis aeruginosa are less than β-cyclocitral, but β-cyclocitral produced by Pseudanabaena is less than Microcystis aeruginosa. Microcystis aeruginosa (M), Pseudanabaena (P1) and Pseudanabaena (P2) used in this study were purchased from purchased from the Chinese Academy of Sciences Wuhan Institute of Aquatic, Taiwan and Wuhan Institute of Aquatic,respectively.The results when M was mixed with P1 showed that the growth ability of M was enhanced in a promotion rate 109%-178% at different initial concentrations, but the metabolic capacity was inhibited in an inhibition rate 8%-41% which led to odorous compounds yield significantly decreasing. At the same time, the growth of P1 was greatly inhibited in an inhibition rate 14-78%at three different initial concentrations ratios.When mentioning mixed culture of M and P2, there was a common feature that the divisional growth of such cell was inhibited in an inhibition 9%-51% and 26-47% when its initial dosing ratio was large. The olfactory-producing ability of M was inhibited in an inhibition rate 3%-30% at three different initial ratios, and the production of odor compounds decreased.However, the olfactory-producing ability of P2 was enhanced in a promotion rate 103-192%,and the production of odor compounds increased.After M and P2 were separately cultured for one month,filter to obtain two algae filtrate 400mL and divide two kinds of filtrate into two parts: 200mL. Use the filtrate to culture alga cells at an initial dosage 108 cells/L of M and P2. The divisional growth of P2 was significantly inhibited in an inhibition rate 22%-76% when it was cultured by M filtrate, while the growth of M was slightly promoted by P2 filtrate. Although P2 was significantly inhibited in M filtrate, the inhibitory effect stimulated cells to produce dozens times of 2-MIB. P2 filtrate not only promoted the divisional growth of M,but also stimulated M producing more β-cyclocitral.M and P2 were added into 100ug/L of 2-MIB and β-cyclocitral respectively, we found the color of M changing from green to blue, then finally milky white. Adding β-cyclocitral speeded the changing of color and the initial color of P2 is dark green, which became shallow since third day, but the overall change is no obvious. Besides, the growth of algal cells were inhibited after adding 100ug/L 2-MIB and P-cyclocitral, the number of M remained stable and then decreased since the sixth day, while P2 reduced quickly after adding chemical substances. We can observe algae cell morphogenesis cultured in various conditions have changed significantly in the transmission electron microscope after adding the odorant after one week. M became smaller and appeared the plasmolysis phenomenon, while P2 is shorter and smaller. After adding the odorant for ten days, the chlorophyll A content of M measured in adding 2-MIB andβ-cyclocitral reduced by 49% and 63%, respectively. And the photosynthetic potential decreased by 52% and 61%, respectively. The chlorophyll A content of P2 measured in adding 2-MIB andβ-cyclocitral reduced by 29% and 18%, respectively. And the photosynthetic potential decreased by 26% and 15%, respectively.