Effects of the green alga Dictyosphaeria ocellata on its surrounding bacterial community [Elektronische Ressource] / Jennifer M. Sneed. Gutachter: Georg Pohnert ; Christian Hertweck

Jenny Wren

Informations

• Publié par: friedrich-schiller-universitat_jena
• Publié le: 01 janvier 2011
• Nombre de lectures: 12
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

 
Effects of the green alga Dictyosphaeria ocellata 
on its surrounding bacterial community 


Dissertation 
Zur Erlangung des akademischen Grades doctor rerum
naturalium (Dr. rer. nat.)
vorgelegt dem Rat der Chemisch-Geowissenschaftlichen
Fakultät der Friedrich-Schiller-Universität Jena

von
Jennifer M. Sneed (M.S.) 
geboren am 15.01.1978 in Columbia, MO (USA)











Gutachter:
1. Prof. Dr. Georg Pohnert Institut für Anorganische und Analytische Chemie
Friedrich Schiller Universität, 07743 Jena

2. Prof. Dr. Christian Hertweck Department of Biomolecular Chemistry
HKI Beutenbergstr. 11a 07745 Jena, Germany

Tag der öffentlichen Verteidigung: 01.12.2010 Acknowledgements 
A lot of hard work went into this PhD and it would not have been possible without the
help and support of many people. First I would like to thank my advisor, Dr. Georg Pohnert,
for providing me with the opportunity to join his lab and work in the field of algal chemical
ecology which might not seem exciting to some, but was my dream. His advice and support
has helped me grow into the scientist that I am today. I would also like to thank Dr. Valerie
Paul for sharing her knowledge of algal chemical ecology and helping me implement my field
experiments in Florida. In addition, my second professor, Dr. Christian Hertweck provided
new insights and numerous helpful suggestions throughout my PhD.
I would also like to acknowledge the staff at the Mote Tropical Research Laboratory for
all of their help and support during my stays in the Florida Keys and Dr. Gunnar Gerdts and
Dr. Antje Wichels for providing bacterial cultures.
Of course I could not have made this journey across the Atlantic without financial support.
I would like to that the International Leibniz Research School for funding my PhD project and
the Link Foundation for funding my three month fellowship in Florida. I would also like to
thank Dr. Dorit Schmidt for all her help organizing housing, bank accounts, visas, and so on.
Life would have been very difficult without her help.
When I started in the Pohnert lab, there were only four students. These four students have
since become four doctors, Dr. Alexandra Barofski, Dr. Jerrit Weissflog, Dr. Matthew
Welling, and Dr. Charles Vidoudez. I would like to thank them for all of their help in those
early months, showing me the ropes and easing my transition into not only a new job, but a
new culture as well. I have to thank Alex especially for taking care of my cats during my first
months in Jena, Jerrit for helping me navigate the German healthcare system, and Matt and
Charles for bringing me Far Side comics in hospital.
As the group grew, we acquired numerous talented chemists and biologists from whom I
have learned a lot, scientifically and otherwise. I thank the entire Pohnert group for their
support throughout my PhD. Special thanks to Carsten Paul for translating my abstract and
CV from English to German and Martin Rempt for his help with GC and NMR analysis.
i
Thanks to Katha Grosser, Kristina Hitzfeld and Astrid Spielmeyer for translating documents
and making phone calls for me in German, and generally helping me navigate the German
bureaucracy. Thanks to Dr. Emily Prince for keeping me sane when I needed a fellow
American around and for all her career advice.
Finally, thanks to my family who have encouraged and supported me throughout my
education and believed in me when I didn’t believe in myself.
ii
Table of Contents 
Acknowledgements .................................................................................................................... i 
List of figures ............................................................................................................................ v 
List of tables ........................................................................................................................... viii 
List of abbreviations ................................................................................................................ ix 
Zusammenfassung ................................................................................................................- 1 - 
Abstract .................................................................................................................................- 3 - 
1  Introduction ..............................................................................................................- 5 - 
1.1  Marine macroalgae: characteristics and importance .........................................- 5 - 
1.2  Importance of bacteria in algal ecology ............................................................- 6 - 
1.3  Algal associated bacterial communities ............................................................- 8 - 
2  Results and Discussion: Effects of D. ocellata and its extracts on natural bacterial
assemblages in the field ..........................................................................................- 17 - 
2.1  Bacterial community analysis .........................................................................- 17 - 
2.2  Comparison of surface-associated bacterial communities within and between
locations. .........................................................................................................- 24 - 
2.2.1  Experimental design ................................................................................- 24 - 
2.2.2  Within-site comparisons .........................................................................- 26 - 
2.2.3  Between-site comparisons ......................................................................- 31 - 
2.3  Effects of algal extracts on the surface-associated bacterial community ........- 34 - 
2.3.1  Surface extracts .......................................................................................- 34 - 
2.3.2  Whole-cell extracts .................................................................................- 36 - 
2.4  Effects of D. ocellata on the natural planktonic bacterial assemblage ...........- 42 - 
2.4.1  Field trip #1: February, 2008 ..................................................................- 43 - 
2.4.2  Field trip #2: February, 2009 ..................................................................- 44 - 
2.4.3  Field trip #3: December, 2009 ................................................................- 48 - 
iii
3  Results and Discussion: Effects of D. ocellata and its organic extracts on the
growth of marine bacteria in co-culture ..............................................................- 53 - 
3.1  Development of co-culture experiment ...........................................................- 53 - 
3.2  Effects of D. ocellata and its organic extracts on the growth of naturally co-
occurring marine bacteria ...............................................................................- 61 - 
3.3  Bioassay guided fractionation of whole-cell D. ocellata extracts. ..................- 72 - 
3.3.1  Crude extracts .........................................................................................- 72 - 
3.3.2  Fractions ..................................................................................................- 76 - 
3.3.3  Sugars and fatty acids .............................................................................- 81 - 
4  Conclusions .............................................................................................................- 87 - 
5  Materials and Methods ..........................................................................................- 91 - 
5.1  Field Experiments ...........................................................................................- 91 - 
5.1.1  Experimental Design ...............................................................................- 91 - 
5.1.2  Bacterial community profiling methodology ..........................................- 97 - 
5.2  Laboratory Experiments ..................................................................................- 99 - 
5.2.1  Development of co-culture experiment ..................................................- 99 - 
5.2.2  Co-culture experiment ..........................................................................- 103 - 
5.2.3  Bioassay guided fractionation of D. ocellata crude extracts ................- 107 - 
Bibliography .....................................................................................................................- 111 - 
Appendices ........................................................................................................................- 118 - 
Selbständigkeiterklärung .................................................................................................- 127 - 
 
iv <