The Research On M. Aeruginosa Growth In Simulative Equipment Of Experiment And Improvement Of The Method For Measuring Microcystin

The serious eutrophication of water body results in frequent breaking out of cyanobacterial blooms, and some genera of cyanobacteria can produce microcystins, which can cause health problems in animals and humans. The effect of microcystins on society,economy and environment has become one of the problems people concerned mostly, as well as the key in the control of cyanobacterial blooms. The sutdies were established with M. aeruginosa, one of the most deleterious species of harmful algal blooms. The environmental factors such as temperature, illumination, pH, zinc, iron, nitrogen and phosphorus were studied to determine their effect on the growth and microcystins production of M. aeruginosa. And in this paper, a new rapid method for toxin extraction was provided based on boiling water bath/liquid-liquid extraction.The results indicate that: M. aeruginosa grew well on the condition that the temperature was 29℃, illumination was 4000Lx, pH was 9.0, Zn²⁺ concentration was 100nmol/L, Fe³⁺ concentration was 10000nmol/L, P concentration was 7.0mg/L, N/P was 30:1. The effects of P concentration on the growth rate of M. aeruginosa under simulative equipment can be described using the Monod equation and Droop equation. The max growth rateμ_max=0.173/d. The P half saturation constant for algae growth K_s=0.275mg/L. The P subsistence quota of algae Q₀=3.803μg/mg(dw). The P half saturation constant for algae growth was 4.990mg/L. The N subsistence quota of algae was 62.137μg/mg(dw). The max growth rate was 0.173/d.The results about the effects of nutrients on the growth of M. aeruginosa and environment factors in simulative equipment of experiment were as flows: The last development of M. aeruginosa growth was phosphorus limitation. With imput of extragenous phosphorus, M. aeruginosa was not limited by phosphorus. When the biomass reached a certain value, the growth of M. aeruginosa translated to light limitation. The growth of M. aeruginosa could be improved by increasing the phosphorus concentration gradually as additional stimuli. M. aeruginosa was luxury phosphorus uptake to cope with phosphorus deficiency when the water environment was breakout of algal blooms. Diurnal changes in the simulative equipment of pH and DO were displayed with the growth of M. aeruginosa.The adsorption and extraction of MCs in M. aeruginosa was studied from the selection of different organic solvents and different time of boiling water bath. The results showed that the extraction was best when used CCl₄ as organic solvent and selected 15min as the time of boiling water bath. Comparing with the traditional extraction methods ,the comparative error of MC-RR and MC-LR were 3% and 9.3%, and the recovery of MC-RR and MC-LR were 94.6% and 95.3%.Effects of growth on M. aeruginosa production of MCs were as flows: The ability of M. aeruginosa to product toxin was related to the developmental stage. The concentration of MCs were significantly higher in the increased logarithmic phase. The M. aeruginosa achieved advantage of competition which exude MCs to inhibit the growth of other species so as to breakout of water bloom.