Date of Award

Fall 2009

Project Type


Program or Major


Degree Name

Master of Science

First Advisor

Cheryl Whistler


Background. Co-evolution of Vibrio fischeri strains with Euprymna scolopes has led to isolates that are superior squid colonists [1, 2]. To better understand how V. fischeri adapts to symbiosis with squid we serially transferred a planktonic Hawaiian isolate, H905 [3], and the natural E. scolopes symbiont, ES114, in squid. We characterized derived isolates for colonization ability as well as other phenotypic traits that have been implicated as being important to symbiosis.

Results. We hypothesized that as a result of adaptation to symbiosis H905 would become more phenotypically similar to ES114. We see this trend in luminescence and siderophore production of derived isolates; however, biofilm production and motility became more different from the natural squid symbiont.

Conclusions. These findings may indicate that H905 utilizes different mechanisms of colonization than symbiotic isolates, or it could also be the result of differential regulation of phenotypes between H905 and ES114 under squid vs. in-vitro conditions.