Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




William Soto

Committee Members

Helen Murphy

Mark Forsyth

Peter Vishton


The purpose of this experiment was to examine how changes in pH would affect the symbiotic and free-living V. fischeri in growth and bioluminescence. We also wished to assess how geographic location and host organism related to patterns of growth and bioluminescence along a pH gradient. To do so, seventeen strains of V. fischeri ecotypes were obtained from diverse host organisms and geographic locations. These strains were then growth on a pH gradient ranging from 4.8 to 10.8. Our results showed that V. fischeri was able to grow on a very wide range, with species growing from pH 5.0 to 10.6. We also found that the optimal growth was achieved at a pH lower than that of actual seawater, approximately at pH 7.4, for all examined strains. Additionally, we found that patterns of growth, especially growth range, correlated more strongly to geographic region than host. Additionally, we found that measures of bioluminescence per cell related more strongly to living phase or organism from which the strains were obtained, in contrast to the results of growth. Overall, we found that slight changes in pH in all strains drastically affected growth.

On-Campus Access Only