中文摘要：

本试验设计了从正常的AA培养基（CK组）到N和P含量只有正常AA培养基1/600的6种培养基.在25℃、2000 lx条件下将宿主席藻在6种培养基中培养8个月后,用显微直接计数法测定了席藻的生长曲线以及噬藻体PP感染宿主席藻的裂解周期与致死率,用离心法测定了噬藻体PP对宿主席藻的吸附率,用一步生长曲线法测定了噬藻体PP的释放量和裂解周期.结果表明：提高N和P含量会促进宿主席藻的生长,统计分析也显示,在对数中期（第6天）,高营养盐浓度中细胞密度显著高于低营养盐浓度中的密度;提高营养盐浓度噬藻体PP的吸附率会显著增高,主要表现为在AA中噬藻体PP的吸附率极显著高于其他组;同时6种培养基条件下噬藻体PP对席藻的致死率变化不大;随着营养水平的升高,噬藻体PP的潜伏期和裂解周期明显缩短,平均释放量显著增加,但裂解宿主的效率却没有显著变化.上述结果说明噬藻体PP对宿主藻的感染力会随着营养水平的提高而明显增强,并可能在水体富营养化进程中发挥着调控藻类种群更替的作用.

英文摘要：

In this study,the cyanobacterium Phormidium was grown under six different nutrient concentrations,ranging from standard AA medium to a 600 × dilutions of that media.After incubation at 25 ℃ and 2000 lx for 8 months,the growth curve for each treatment was measured by direct counting of cell numbers.Additionally,the lytic cycle and mortality rate were determined by monitoring the lytic effect of the host cells using microscopy.The adsorption rate of cyanophage PP was measured using the centrifugation method,where the burst size and lytic cycle were confirmed by measuring the one-step growth curve.Results indicated that elevated TN and TP could significantly promote the growth of Phormidium.Statistical analysis showed that during the mid-log phase（ day 6 th） cell densities were significantly higher under high nutrient conditions.Additionally,the adsorption rate in standard AA medium was significantly higher than that in the other five dilution media.Although nutrient conditions did not affect mortality rate significantly,the latent period and lytic cycle of cyanophage PP were obviously shortened.Moreover,the average burst size of cyanophage PP increased significantly with increasing the nutrient concentration.These results not only proved that high nutrient concentration could promote cyanophage infectivity,but also implied that cyanophage might play an important ecological role in adjusting the succession of algal populations in the progress of eutrophication.