Temporal And Spatial Distribution Of Virioplankton In Donghu Lake And Preliminary Study On Its Genetic Diversity

In this study, we investigated temporal and spatial distribution of virioplankton in small water-bloom pounds and Donghu Lake in Wuhan, also, genetic diversity of virioplankton was analyzed in Donghu Lake, the results are as follows: we carried out a study on the distribution of virioplankton for a comprehensive investigation in two water bodies ( Luoyandao and Guanqiao) from April to December in 2005. The results indicated that although the viral abundance was higher in more eutrophic water body, there was no significant correlation between viral abundance and nutrient concentrations. In Luoyandao and Guanqiao sampling sites, the average viral abundances were 2.99×10⁸ VLPs·mL^-1 and 4.24×10⁸ VLPs·mL^-1 respectively (the peak values appeared from September to October), the average chlorophyll a concentrations were 96.66μg·L^-1 and 166.74μg·L^-1 respectively. In Guanqiao sampling site, the correlation level between viral abundance and chlorophyll a concentration was lower in the identical month (r= 0.634, P<0.05) than that the chlorophyll a concentration was ahead of one month ( r= 0.809, P < 0. 01), while there was no significant correlation between viral abundance and the chlorophyll a concentration on the next month. The results confirmed the ideal that the abundance of virioplankton was mainly decided by the biomass of bloom-algal biomass, while it denied the hypothesis that virioplankton could control the biomass of M. aeruginosa.From August in 2004 to July in 2005, we detected the environment parameters (temperature, light intensity, transparence, pH value, N concentration and P concentration) and biological activity (viral abundance, bacterial abundance, and chlorophyll a concentration) at six stations in Donghu Lake (30°33'N, 114°23'E). Viral abundance at six stations was higher in late summer than that in other seasons, and the lowest values were observed in winter. It was found that in the Donghu Lake, most virioplankton which origined from the phase of bacteria were bacteriophage. Our results indicated that the temporal changes of virioplankton possibly depended on bacterial activity. Water temperature, trophic conditions and other factors couldn't directly affect virioplankton abundance, but these factors could affect the distribution of bacteria, consequently indirectly affect the distribution of virioplankton. Through concentration and DNA extraction processing of water samples, PCR was used to amplify a fragment of the gene(g)23, which coded caspid vertex protein. Temperature gradient gel electrophoresis (TGGE) of PCR amplified g23 gene fragments was used to examine variations in viroplankton community structure in Donghu Lake. This technique could distinguish at least four DNA bands, providing a rapid insight into genetic diversity, so TTGE is a reliable technique and a valuable tool for viroplankton gene diversity studies. It also indicated that in water bodies which had different trophic levels, viroplankton genetic diversity was obviously different.