Physiological plasticity of marine phytoplankton revealed by untargeted metabolomics

The majority of the earth's surface is covered by oceans. Within their photic zones, microscopically small algae are fixing carbon dioxide in form of organic molecules, thus building the base of the marine food web. The metabolic plasticity of these algae allows them to respond to ecological ch...

Full description

Bibliographic Details
Main Author: Kuhlisch, Constanze
Other Authors: Pohnert, Georg, Sasso, Severin, Spiteller, Dieter
Format: Doctoral or Postdoctoral Thesis
Language:English
Published: 2018
Subjects:
Online Access:https://doi.org/10.22032/dbt.38222
https://nbn-resolving.org/urn:nbn:de:gbv:27-dbt-20190225-0817591
https://www.db-thueringen.de/receive/dbt_mods_00038222
https://www.db-thueringen.de/servlets/MCRFileNodeServlet/dbt_derivate_00044342/CKuhlischThesis.pdf
http://uri.gbv.de/document/gvk:ppn:1066494312
Description
Summary:The majority of the earth's surface is covered by oceans. Within their photic zones, microscopically small algae are fixing carbon dioxide in form of organic molecules, thus building the base of the marine food web. The metabolic plasticity of these algae allows them to respond to ecological changes such as grazing, thereby increasing their fitness and survival. However, most of the metabolites produced by microalgae are not yet known. State-of-the-art metabolomics techniques allow the untargeted and sensitive analysis of intra- and extracellular metabolites both in laboratory cultures and the ocean. The aim of this thesis was to describe physiological plasticity of marine microalgae with regard to grazing interactions. Thus, I conducted a comprehensive review on metabolomics in the field of chemical ecology, and introduced a systematically optimized and standardized protocol for the metabolic analysis of marine algae. Furthermore, I developed a UHPLC-APCI-HRMS analysis for the simultaneous profiling of volatile and non-volatile oxylipins - two compound classes that are released by microalgae as grazing defence, and that had to be analysed separately in the past. To better understand the influence of algal physiology on trophic interactions with marine grazers, I described the physiological plasticity of the abundant cold-water species Phaeocystis pouchetii in laboratory cultures, identified by an untargeted metabolomics approach endo- and exometabolites that are potential physiological markers for different growth phases, and used these markers to characterize natural P. pouchetii blooms in the Northeast Atlantic. In addition, I showed that during filtration of P. pouchetii metabolites can be released which influence the specific growth of marine bacteria. In summary, this thesis provides new insights into the role of physiological and thus functional parameters in the ecology of marine algal communities. Der Großteil der Erde wird von Meerwasser bedeckt, in welchem mikroskopisch kleine Algen ...