Absorption And Mechanism Response Of Two Waterbloom-forming Cyanobacteria At Different Forms Of Phosphorus In The Shanzai Reservoir

Since built in 1992,Shanzai reservoir has played a important role in fujian province,it undertakes the function of farmland irrigation,flood control,power generation and became the second water source for fuzhou resident. However, due to the activities and lifestyles changes of human, waterbloom-forming cyanobacteria which caused by water eutrophication occurred frequently since it was first discovered in 1997.The microcystins of cyanobacteria can endanger the safety of drinking water and human health.Therefore, the classification properties,poison characteristicsand the physiological response mechanism of waterbloom-forming cyanobacteria nutrient absorption has a practical significance for reveal the causes of cyanobacteria bloom and as early warning surveillance of Shanzai reservoir toxic cyanobacteria bloom。The main contents of this paper are as follows:(1) Separate and purificate waterbloom-forming cyanobacteria from Shanzai reservoir, identified them by molecular markers of 16SrRNA on the basis of morphological identification,result shows that they are Microcystis aeruginosa B1-14 and Anabaena planctonica B1-15;(2) Detecte the microcystin of the two waterbloom-forming cyanobacteria with the method of whole-cell PCR and HPLC. result shows that Microcystis aeruginosa B1-14 can produce MC-LR and has two kind of microcystin genes mcyA and mcyB. but the genes and microcystin are not exist in Anabaena planctonica B1-15,so Microcystis aeruginosa B1-14 can produce microcystin but Anabaena planctonica B1-15 can not;(3) Studied the growth effect of the two waterbloom-forming cyanobacteria in different forms of phosphorus (four inorganic phosphorus and two organic phosphorus).Compared the different forms of phosphorus uptake ability and its response mechanism through the determination of specific growth rate.exteacellular total phosphorus and alkaline phosphatase activity.Results shows that the orthophosphate (potassium dihydrogen phosphate, potassium dihydrogen phosphate)absorption rate and alkaline phosphatase activity were greater than poly phosphate (sodium pyrophosphate, sodium phosphate, sodium phosphate) and organic phosphate (ATP, alpha glycerophosphate) in the two waterbloom-forming cyanobacteria.It is indicated that orthophosphate was the most suitable phosphorus salt for the two waterbloom-forming cyanobacteria,but they can absorb part of poly and organic phosphates under the action of alkaline phosphatase.Phosphorus absorption rate of Microcystis aeruginosa B1-14 was higher than Anabaena planktonic B1-15,however whose alkaline phosphatase activity was greater than Microcystis aeruginosa.That’sproved the characteristics of Microcystis aeruginos B1-14 absorbing and accumulating excess phosphorus,and the ability of produce alkaline phosphatase has positive correlation with its surface area and volume ratio;(4) Based on the above research,we chose orthophosphate (potassium hydrogen phosphate) and ATP as phosphorus source respectively, studied the characteristics of phosphorus absorption kinetics of the two waterbloom-forming cyanobacteria, discussedtheir competitive ability and possible advantages of succession sequencethrough. Kinetic parameters. Results show that the obvious reaction of low concentration of the two waterbloom-forming cyanobacteria under different phosphorus concentration was 0.54 mg·L-1. The growth rate of Microcystis aeruginosa B1-14 increased significantly with the increase of phosphorus concentration between 0.54-5.4 mg·L-1, the growth rate of Anabaena planctonica B1-15 was not increased obviously and below than Microcystis aeruginosa B1-14 under the same conditions.But growth rate of the two waterbloom-forming cyanobacteria no longer increased when phosphorus concentration more than 5.4 mg·L-1. In inorganic phosphorus conditions, the biggest growth rate(0.18418d-1) and half saturation coefficient (0.019785mg·L-1) of Microcystis aeruginosa B1-14 were greater than that of Anabaena planctonica B1-15(which were 0.12825d-1 and 0.079785mg·L-1 respectively).So we can conclude that Microcystis aeruginosa B1-14 became advantage algae when the concentration of inorganic phosphorus was greater than 0.54mg·L-1, otherwise Anabaena planctonica B1-15 became advantagealgae. Under organophosphate conditions,the half saturation coefficient and the larggest growth rate of the two waterbloom-forming cyanobacteria were small, and the difference was not obvious. This also confirmed tha the two waterbloom-forming cyanobacteria mainly absorpt soluble inorganic phosphorus, but they can make use of organic phosphorus;(5) Study the competition effect and the two waterbloom-forming cyanobacteria filtrate allelopathy.Result shows that Microcystis aeruginosa B1-14 has more growth advantage than Anabaena planctonica Bl-15in competetion conditions,and Anabaena planctonica B1-15 filtrate to Microcystis aeruginosa B1-14 has greater effect than Microcystis aeruginosa B1-14 filtrate to Anabaena planctonica B1-15;(6) Study the physiological and biochemical effects of waterbloom-forming cyanobacteria under some common organophosphorus pesticides.In EC50 conditions, the sensitivity order of Microcystis aeruginosa B1-14 to organophosphorus pesticide as follows:dimethoate> phoxim> glyphosate;and Anabaena planctonica B1-15 to organophosphorus pesticide is:dimethoate>glyphosate>phoxim,and M. B1-14 is more sensitive than A B1-15.