Effects Of Malathion On The Growth And Phosphorus Use Of Microcystis Aeruginosa

Water bloom had been an environmental problem that disturbed human lives in recent years.The input of excessive phosphorus was one of most important reason that led to water bloom.The organic phosphorus pesticides played an important role in water bloom.Because the organic phosphorus pesticides in aquatic environment can be transformed to phosphorus forms that Cyanobacteria could be used.In an attempt to know the growth,development and excessive proliferation of cyanobacteria,this work investigated growth and phosphorus metabolism of M.aeruginosa cultured in medium containing malathion of different concentration in the presence and absence of DIP,respectively.The degradation of malathion was also studied.The growth of M.aeruginosa showed that malathion of low concentration stimulated the growth of Anabaena sp.,Anabaena Oscillarioides Bory and Microcystis aeruginosa whereas malathion of high concentration had obvious inhibition effect on the growth of M. aeruginosa.Malathion of 0.06 mg/L had obvious stimulation effect on the growth of M.aeruginosa with a stimulation ratio of 34.7%when DIP was absence in the culture.The specific changes of all kinds of phosphorus forms could be concluded as follows:The content of intracellular orthophosphate in M. aeruginosa increased with decreasing of malathion concentration in cultures which was free of DIP during experimental period.When DIP was available in culture,intracellular orthophosphate of M.aeruginosa treated by malathion was similar with that of control,except that the former was higher than the later at 2th and 4th day because of adsorption and transformation of malathion by M.aeruginosa.The intracelluar total phosphorus increase with increasing of concentration of malathion only in the first 6 days when DIP was available.For M.aeruginosa in culture not containing DIP,intracelluar total phosphorus showed the positive relationship with concentration of malathion in the whole experimental period.Malathion had not significantly effect on varivation of Polyp in M. aeruginosa in medium with DIP,and PolyP in M.aeruginosa increased with decreasing of concentration of malathion when DIP was absence in culture. On the basis of the results of malathion degradation by Microcystis aeruginosa,it was found that malathion degradation was improved effectively by Microcystis aeruginosa in BG 11 medium and the half life of malathion was advanced from 74 h to 36 h in this experiment.