Lysogeny: Practical Applications and New Discoveries

EPA Grant Number: U916201
Title: Lysogeny: Practical Applications and New Discoveries
Investigators: McDaniel, Lauren D.
Institution: University of South Florida
EPA Project Officer: Zambrana, Jose
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $121,543
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Fellowship - Microbiology , Academic Fellowships , Biology/Life Sciences


The objectives of this research project are to: (1) study lysogeny in marine picoplankton (Synechococcus) documented by prophage induction; and (2) develop a Marine Prophage Induction Assay (MPIA) to screen marine environmental samples for the presence of mutagenic contaminants.


The research for Objective 1 is important because of the vital role of autotrophic picoplankton in worldwide primary productivity and carbon cycling. To document this phenomenon, I participated in a 13-month seasonal study of lysogeny in the marine environment. At the completion of the study, I demonstrated that not only does lysogeny occur in marine picoplankton, but also that there is an observable seasonal pattern to the induction events. Lysogeny is believed to be a survival strategy of viruses, allowing them to survive under adverse environmental conditions or during low host abundance. Our experimentation to date has demonstrated that nutrient stimulation can stimulate or increase the level of prophage induction in natural populations. I will determine the environmental cues that trigger integration and induction of phage. As part of this effort, I participated in a research cruise in July 2001, to investigate the role of nutrient limitation and stimulation to prophage induction in Synechococcus. These data currently are being analyzed. In addition, I have more than 30 Synechococcus isolates in culture. One of these isolates has demonstrated prophage induction under laboratory conditions. Work is in progress to document the presence of integrated prophage using molecular methods. Once integrated prophage is documented, work will begin on investigating the potential natural triggers of prophage induction as well as the genetic basis of lysogeny. I am developing an MPIA to screen marine environmental samples for the presence of mutagenic contaminants. This assay is based on the well-documented sensitivity of lysogenic bacteria to any DNA-damaging agent. A similar assay called the Microscreen Assay has been developed and currently is in use to screen freshwater environmental samples. The first phase of the project screens marine lysogenic isolates for use in the assay, procedure development, and initial testing of the assay. The second phase of the project adapts the assay to environmental samples, including sediment, and to screen a wider range of chemical agents to determine the sensitivity of the assay.

Supplemental Keywords:

fellowship, lysogeny, marine picoplankton, Synechococcus, Marine Prophage Induction Assay, MPIA, mutagenic contaminants, lysogenic bacteria, marine lysogenic isolates.

Progress and Final Reports:

  • 2003
  • 2004
  • Final