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The Role of Lysogeny in the Microbial Ecology of Lake Matoaka

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Author: Hart, Erica Leigh
Advisor: Williamson, Kurt E.
Committee Members: Chambers, Randolph M.; Forsyth, Mark H.; Lockwood, Rowan; Terukina, Jorge L.
Issued Date: 2010-05-17
Subjects: Freshwater ecology
URI: http://hdl.handle.net/10288/2034
Description: Viruses play important roles in aquatic ecosystems. They drive nutrient cycling and maintain a diverse microbial community. Temperate phages, or those viruses that have the ability to reproduce lysogenically, may also contribute to host survival and the genetic diversity of their hosts. The study of lysogeny in various ecosystems is valuable to understanding microbial communities. Information on freshwater ecosystems is of particular importance, as lysogeny in marine systems is more widely studied This study examined the occurrence of lysogeny in a hypereutrophic, freshwater lake in Williamsburg, VA for the months of November and December 2009 and February and March 2010. Mitomycin C was added to ambient lake water and inductions were measured as the increase in viral direct counts from control sample counts using epifluorescence microscopy. March water samples were the only to demonstrate significant prophage induction. Burst size ranged from 0 to 98.53 and lysogenic fractions ranged from 2.67% to 54.50%. No significant correlations were found between water quality data and biological data. Experiments were also carried out with different inducing agents on a lake water sample and E. coli (λ) lysogens, including mitomycin C, ultraviolet radiation, and an herbicide (SedgeHammer). Mitomycin C induced the most viruses in E. coli (λ), while the highest concentration of the herbicide induced the most viruses in the ambient lake water. The results of the study indicate that lysogeny is more prevalent in March, when nutrient concentrations are lower as a result of curly pondweed (Potamogeton crispus) growth. Finally, mitomycin C, ultraviolet radiation, and herbicide were all shown to induce phage production from lysogenic cells, with the herbicide inducing the greatest number of prophages in environmental samples.
Degree: Bachelors of Science in Biology

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