Abstract:

Microcystis aeruginosa,a kind of bloom algae,may cause severe damage in lakes,reservoirs and some other water bodies in China.In the present study,direct ammonium molybdate spectrophotometric method was used to measure the phosphate uptake of unicellular M.aeruginosa.The concentration of uptake phosphate was equal to the concentration value measured by ammonium molybdate spectrophotometric method after subtracted from dissoluble total phosphate.Comparing the results of three kinds of pretreatments (hydrochloric acid,ultrasonic fragmentation and frigorific fragmentation treatment),it is found that polyphosphate (phosphate) was not dissociated in cells of M.aeruginosa but associated with bioactivity components of the cells.According to the determination method,the phosphorus uptake of M.aeruginosa,which was cultured in modified MIII cultures,was studied under different N,P concentrations.The results showed that:①Under constant N/P ratio,N/P=7/15,the accumulated quantity of phosphorus in M.aeruginosa increased with the increased initial P concentration in the media;②Under the constant N concentration,the phosphorus uptake of M.aeruginosa was correlated positively with the initial P concentration;③Under the constant P concentration,the accumulation of phosphorus by M.aeruginosa was correlated negatively with the initial N concentration,but the trend was not obvious and the effect of initial N concentration on the uptake P quantity became ruleless when the initial N concentration reached a higher level (21 mg/L).

Key words: Microcystis aeruginosa, phosphate, polyphosphate, uptake