Taxonomic and genetic analysis of Marinobacter sp. HP15 and its chemotactic behaviour towards the diatom Thalassiosira weissflogii

  • Aggregation of micro-algae, mainly of diatoms, is an important process in marine pelagic systems leading to the sinking of particulate organic matter in form of marine snow. This process has been studied extensively, but the specific role of heterotrophic bacteria, their genes, gene products, and secondary metabolite signals for this process has largely been neglected. A bilateral model system consisting of the diatom Thalassiosira weissflogii, and the bacterial strain, Marinobacter sp. HP15, was found suitable for an in-depth molecular analysis by attachment assays, TEP production determination, and aggregation experiments. Following the taxonomic and genomic description of the bacterial model strain, its genetic accessibility was demonstrated and the interaction has been studied by molecular and bioinformatics investigations. Chemotaxis- and motility-deficient mutants were generated and their phenotypes were described in appropriate assays in order to investigate the particular role(s) of these processes in diatom-bacteria interactions. HP15 was attracted to diatom homogenate in soft agar assay and chemotaxis-deficient mutants showed a decreased ability to attach to T. weissflogii supporting the importance of chemotaxis in diatom-bacteria interactions. These and future results based on the model system will improve our understanding of bacteria-phytoplankton interactions and how they influence the flux and cycling of carbon during marine snow formation.

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Publishing Institution:IRC-Library, Information Resource Center der Jacobs University Bremen
Granting Institution:Jacobs Univ.
Author:Eva Käppel
Referee:Matthias Ullrich, Gunnar Gerdts, Laurenz Thomsen, Georg Pohnert
Advisor:Matthias Ullrich
Persistent Identifier (URN):urn:nbn:de:101:1-2013052812352
Document Type:PhD Thesis
Language:English
Date of Successful Oral Defense:2011/01/18
Date of First Publication:2011/01/31
PhD Degree:Marine Microbiology
School:SES School of Engineering and Science
Library of Congress Classification:Q Science / QK Botany / QK504-638 Cryptogams / QK564-580.5 Algae. Algology / 568.M52 Microalgae
Call No:Thesis 2011/3

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