Date of Completion


Embargo Period



Biofilm, Extracellular matrix, Archaea, Horizontal Gene Transfer, Sociomicrobiology, Extracellular DNA, Haloferax volcanii, Haloarchaea, Halophile

Major Advisor

R. Thane Papke

Associate Advisor

J. Peter Gogarten

Associate Advisor

Spencer Nyholm

Field of Study



Doctor of Philosophy

Open Access

Campus Access


This thesis seeks to advance the field of archaeal biofilms and related social behaviors through the study of the haloarchaeon Haloferax volcanii. Biofilms are multicellular microbial communities enmeshed within an extracellular matrix. Close proximity between biofilm cells facilitates many emergent behaviors and phenotypes, from communication mechanisms, to cellular differentiation, collective activities, and gene transfer. For this reason, microbial biofilms offer a simplified system for studying development, the evolution of multicellularity, and social behaviors. However, almost all investigations of biofilms to date have been conducted in a handful of model bacterial systems.

My work has reported on the structural development and extracellular matrix composition of Hfx. volcanii biofilms and establishes this species as an excellent model for studying archaeal biofilm biology. Furthermore, several related biological phenomena were discovered in Hfx. volcanii, including an ability to metabolize extracellular DNA (an abundant community environmental resource and biofilm component), cellular differentiation, social motility, and genetic exchange in biofilms through a cell-contact-dependent mechanism known as mating. These studies lay a foundation for characterizing genetic determinants of archaeal biofilms, as well as novel archaeal collective-behaviors, cell-to-cell interactions and functional cell types, and the molecular machinery for extracellular DNA processing.