Assessment of Ecological Roles of Cyanophages in Aquatic Environments using Molecular Approaches

点击翻译按钮获取中文摘要

High concentrations of morphologically diverse marine Synechococcus cyanophages (viruses which infect Synechococcus spp) are found in nature. Co existence of such abundant and diverse cyanophages and cyanobacteria in aquatic environments has been thought to be an important factor in regulating the community diversity of both groups. Some recent studies suggest cyanophages may account for 30% of Synechococcus mortality in marine ecosystems. However, other studies suggest it is unlikely for cyanophages to be major contributors to Synechococcus mortality in either inshore or offshore waters. The evidence supporting these two different opinions was based on data collected from bacterial cultures in the laboratory; at conditions which may be quite different from what occurs in nature. So far, there are no biological means to detect and quantify in situ how many Synechococcus cells are being infected by phages. To assess the effects of phages on natural microbial mortality, it is important to determine the percentage of the natural population that is being infected. Development of in situ molecular detection techniques can provide new insight into the ecological impact of phages on Synechococcus mortality in natural aquatic environments. This research is composed of two parts. First, DNA polymerase gene (DNA pol) sequences from several marine cyanophages which infect representatives of Synechococcus strains will be characterized and subsequently used for studying diversity and genetic relationships among Synechococcus cyanophages in seawater. The second part of the study will develop in situ molecular detection of the percentage of Syncechococcus cells infected by various strains of cyanophages in marine environments.