Document Type



Master of Science (MS)



First Advisor's Name

Laurie L. Richardson

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Miroslav Gantar

Third Advisor's Name

Eric von Wettberg


cyanobacteria, black band disease, hot springs, physiology, microcystin, sulfide

Date of Defense



Planktothricoides raciborskii and Roseofilum reptotaenium are physiologically similar, yet ecologically distinct organisms found in a hot spring outflow and coral black band disease (BBD), respectively. The aim of this study was to elucidate the relationship between R. reptotaenium and sulfide in BBD, to compare microcystin (MC) production in response to environmental factors, and to determine chemotactic responses to MC and sulfide by the two organisms. Results showed that the pathogenicity of R. reptotaenium in BBD is dependent on sulfate-reducing bacteria as secondary pathogens. Roseofilum reptotaenium produced significantly more MC than P. raciborskii, as measured using ELISA. Roseofilum reptotaenium was negatively chemotactic to sulfide, determined using horizontal and vertical gradients in agar, while P. raciborskii was not affected. Neither cyanobacterium was chemotactic to MC in the agar assays. The ecophysiology of P. raciborskii and R. reptotaenium in relation to MC production and response to sulfide reflected their pathogenic versus non-pathogenic status.





Rights Statement

Rights Statement

In Copyright. URI:
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).