Effect Of Virioplankton In Donghu Lake On Host Lysis Rate And Lysogenic Induction Rate

This thesis researches some ecological features about virioplankton in Donghu Lake,Wuhan,including the viral spatial and temporal distribution,the viral lysis on host and lysogenic induction of host.The temporal and spatial distribution of viral and host abundances in three sub-lakes of the Donghu Lake(Tuanhu,Guozhenghu,and Guanqiaohu Lake)were investigated throughout 2017-2018 yrs.The results indicated that the virioplankton presented seasonal and spatial dynamis characteristics.The viral abundance in summer was significantly higher than that in winter(P<0.05),and the viral abundance was significantl positively correlated with the nutrient level of water body(P<0.05).The viral abundance in the Donghu Lake was mainly affected by host abundance,water temperature,dissolved oxygen and nutrient levels.By the modified gradient dilution culture method,the viral caused host lysis rate in the three sub-lakes of Donghu Lake was monitored through year 2017 and 2018.The viral caused bacteriplankton lysis rate was 32.5%±18.6% in Tuanhu sub lake,30.2%±19.6% in Guozhenghu sub lake,and 17.8%±9.9% in Guanqiaohu sub lake.The viral caused phytoplankton lysis rate was 24.2%±14.6% in Tuanhu sub lake,27.6%±19.0% in Guozhenghu sub lake,and 16.1%±8.3% in Guanqiaohu sub lake.Principal component analysis and multivariate stepwise regression analysis showed that the viral caused bacteriplankton lysis rate was mainly affected by the viral abundance,the bacteriplankton abundance,the total phosphorus content,the CODMn,the dissolved oxygen and the water temperature.The viral caused phytoplankton lysis rate was mainly affected by the total nitrogen concentration,the total phosphorus concentration,the chlorophyll a content,and the water transparency in Tuanhu sub lake.There were no correlations between environmental factors and viral caused phytoplankton lysis rate in Guozheng and Guanqiao sub lakes.The host lysogenic induction rate in the three sub-lakes of Donghu Lake was obtained by the mitomycin C induction method.The bacteriplankton lysogenic induction rate was 33.9%±9.4% in Tuanhu sub lake,36.7%±8.3% in Guozhenghu sub lake and 28.1%±12.2% in Guanqiaohu sub lake.The phytoplankton lysogenic induction rate was 24.3%±9.2% in Tuanhu sub lake,21.1%±6.7% in Guozhenghu sub lake and 20.3%±7.7% in Guanqiaohu sub lake.Principal component analysis and multiple stepwise regression analysis showed that the bacteriplankton induction rate was affected by the total phosphorus concentration in Guanqiao sub lake,and no correlations between environmental factors and bacteriplankton induction rate were observed in Tuanhu and Guozheng sub lakes.Correlation analysis showed that the phytoplankton induction rate was significantly positively correlated with viral caused phytoplankton lysis rate in Guozheng sub lake(p<0.05),and environmental factors showed no effects on phytoplankton induction rate in the other two sub lakes.