PS 19-190 - Lysogenic bacteriophage as a gene reservoir in gut ecosystems

Background/Question/Methods

Microbial ecosystems are integral to the biological functioning of many organisms and larger ecosystems. A core component of microbial ecosystems are viruses that interact with bacteria (bacteriophages). One type of bacteriophage goes through the lysogenic cycle where, after injection, bacteriophage DNA gets incorporated into the bacterial chromosome. Often the DNA that has been incorporated provides the bacteria with beneficial functions. In a sense, horizontal gene transfer by lysogenic bacteriophage could provide gene transfer over large spatial and temporal scales creating a reservoir of beneficial bacteriophage genes. This reservoir of beneficial bacteriophage genes may be important for the gut microbiota of animals to enable buffering of variability. Therefore, I am examining whether lysogenic bacteriophage can provide a reservoir of beneficial genes that assist the gut microbiota in buffering stochasticity. I am using a mathematical model of gene carrier and non-gene carrier bacteria where the relative proportions of these bacteria can change via competitive selection, conjugation, and lysogenic bacteriophage-mediated transduction. Through allowing conjugation versus transduction and changing the stochasticity temporal scale of the selection on the gene, I will examine the different temporal scales of conjugation and transduction, and assess the viability of bacteriophage mediated transduction as a reservoir of beneficial genes.

Results/Conclusions

Preliminary results indicate that lysogenic bacteriophage can provide a reservoir when the periodicity of stochasticity is long. When periodicity is shorter, conjugation and asexual reproduction overwhelms the reservoir potential of bacteriophage. Further research will examine the fitness tradeoffs of lysogenic bacteriophage in the face of variability for each level within the animal host: the bacteriophage, the bacteria, and the animal host. Taken together, this research contributes to a greater understanding of bacteriophage-bacteria interactions and ultimately to the multiple mechanisms that animals use to deal with variability.