University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 8-2018 MOLECULAR CHARACTERIZATION OF FACTORS CONSTRAINING THE SUCCESS AND TOXICITY OF MICROCYSTIS BLOOMS Lauren Elisabeth Krausfeldt University of Tennessee, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation Krausfeldt, Lauren Elisabeth, "MOLECULAR CHARACTERIZATION OF FACTORS CONSTRAINING THE SUCCESS AND TOXICITY OF MICROCYSTIS BLOOMS. " PhD diss., University of Tennessee, 2018. https://trace.tennessee.edu/utk_graddiss/5030 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Lauren Elisabeth Krausfeldt entitled "MOLECULAR CHARACTERIZATION OF FACTORS CONSTRAINING THE SUCCESS AND TOXICITY OF MICROCYSTIS BLOOMS." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Microbiology. Steven W. Wilhelm, Major Professor We have read this dissertation and recommend its acceptance: Alison Buchan, Shawn R. Campagna, Karen G. Lloyd Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) MOLECULAR CHARACTERIZATION OF FACTORS CONSTRAINING THE SUCCESS AND TOXICITY OF MICROCYSTIS BLOOMS A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Lauren Elisabeth Krausfeldt August 2018 Copyright © 2018 by Lauren E. Krausfeldt. All rights reserved. ii DEDICATION To my dad, my hero. And my sister, forever my best friend. iii ACKNOWLEDGEMENTS I would first like the acknowledge Dr. Wilhelm for being an exceptional advisor. I am incredibly grateful for the tremendous research opportunities I have been given in graduate school. Thank you for your mentorship, support and advice in research and in life. Thank you for creating and encouraging a positive work environment. I am truly appreciative to have worked in such a collaborative atmosphere with people I call friends. To my committee members, I look up to you all with great admiration and so appreciate your guidance over the years. I have to especially thank my undergraduate research advisor Dr. Tamara Marsh for giving me the opportunity to dive into research and always believing in me. I wouldn’t be where I am today without her. I have been lucky to have collaborated with many wonderful people – Drs. Boyer, Tang, Bullerjahn, McKay, Steffen, Bodrossy, Hector, Abigail and many more, thank you for all of your input on my work and the many valuable discussions. I also have to thank Elizabeth McPherson for not only being a tremendous teaching supervisor but also a great friend. To my labmates, past and present – I am so grateful for our time commiserating over failed experiments, the celebration of our successes, and our talks about life and research in the lab and out. A special shout needs to go out to Gary LeCleir for all the help throughout the years! I am so lucky to have such a wonderful support system in my family and friends. Thank you all for your love, encouragement and never-ending support even when distance sometimes keeps us apart. A special thank you goes to all of the friends I have made in Knoxville – I love you all, thank you for making Knoxville home. I have to especially thank my family for always making sure that I know how proud they are of me. And to my little family here in Knoxville – Bob, Theodore, and Rocky, I love coming home to you at the end of every day! iv ABSTRACT Harmful cyanobacterial blooms (cyanoHABs) have detrimental effects on freshwater lakes and reservoirs around the world. CyanoHABs severely reduce water quality, altering the food web and disrupting fishing and tourism industries. In addition, many bloom-forming cyanobacteria have the capacity to produce potent toxins, making the negative impacts of cyanoHABs of ecological and economic importance and a serious public health risk. Microcystis spp., which are the typically dominating cyanobacteria in blooms, often produce thick scums, taste and odor compounds and the hepatotoxins, microcystin, implicated in water advisories, human and animal poisonings and drinking water shutdowns globally. Primarily driven by anthropogenic nutrient loading and climate change, Microcystis blooms are on the rise, not only increasing in frequency but also intensity. Nitrogen (N) and phosphorus (P) are considered the most important nutrients in driving bloom formation and persistence but historically management practices have solely focused on P abatements. Large inputs of N into the environment have now been tied to the increased prevalence of toxic Microcystis. To better understand the role of N and other environmental factors impacting the success and toxicity of Microcystis, a number of molecular techniques were employed to characterize bloom community dynamics and the physiology of Microcystis. Results from environmental studies generated new hypotheses about the role of heterotrophic bacteria in N-cycling and microcystin degradation, while observations from laboratory studies provided novel insight into the metabolism of N by Microcystis and subsequent microcystin production was proposed. Together, the findings presented here can be extrapolated to the natural environment and provide greater insight into the mechanisms that contribute to cyanoHAB expansion and toxicity. v TABLE OF CONTENTS Harmful cyanobacterial blooms ............................................................................................... 2 Microcystins: Toxicity and risks.............................................................................................. 3 The fate of microcystins in the environment ............................................................................ 8 Microcystis and the microcystin production........................................................................... 12 Factors that influence the success and persistence of Microcystis blooms .............................. 15 Nitrogen and phosphorus: Has the debate come to an end? .................................................... 17 References ............................................................................................................................ 21 Publication note .................................................................................................................... 29 Abstract ................................................................................................................................ 30 Introduction .......................................................................................................................... 31 Methods ................................................................................................................................ 33 Sample collection and environmental parameters .............................................................. 33 RNA extraction ................................................................................................................. 34 Microarray analyses .......................................................................................................... 36 Multivariate Analysis ........................................................................................................ 36 Results .................................................................................................................................. 39 Status of the lake ............................................................................................................... 39 N-cycling gene expression................................................................................................. 43 Discussion............................................................................................................................. 49 Acknowledgements ............................................................................................................... 56 Appendix .............................................................................................................................. 63 vi Figures .............................................................................................................................. 63 Tables ............................................................................................................................... 68 Supplementary Information ............................................................................................. 101 References ............................................................................................................................ 57 Publication note .................................................................................................................. 107 Abstract .............................................................................................................................. 108 Introduction .......................................................................................................................