Visualisierung mikrobieller Gemeinschaften auf marinem Mikroplastik: Identifikation, Interaktionen und Auswirkungen
Physik, Chemie und Biologie des Meeres
Zusammenfassung der Projektergebnisse
When plastic enters the ocean it is subject to fast colonization by microbes within a few hours. Subsequently, the plastic surface is rapidly covered by a biofilm dependent on marine region, season and residence time of the plastic marine debris (PMD) in the ocean. Due to the durability of plastic, it is distributed throughout the oceans and can transport microbial communities in remote foreign ecosystem with unknown consequences. Thus, it is essential to understand the composition, succession and interactions of microbial communities residing on PMD. Molecular techniques such as high-throughput sequencing identified the members of the so-called 'Plastisphere' communities. However, these methods give no insight in the spatial distribution and interactions of microbes on plastic, which is essential to identify symbioses and competitions, or to identify potential degraders of plastic polymers. To visualize the 'Plastisphere' community I used an advanced microscope technique called CLASI-FISH (Combinatorial Labeling and Spectral Imaging - Fluorescence In Situ Hybridization). This method enables the phylogenetic identification of around 10 different bacteria groups directly on the PMD surface. I imaged early stage biofilms on polyethylene submerged up to 5 weeks in surface seawater in the coastal North and Tropical Atlantic Ocean and in the North Sea. The Atlantic samples were dominated by Rhodobactereace (half of the bacteria cells) followed by Bacteroidetes. Diatoms covered the entire plastic surface after 1 to 2 weeks and were surrounded by different bacteria groups suggesting close inter-domain interactions such as nutrient exchange. Overall, I observed a homogenous distribution of the different bacteria groups on PMD suggesting a random recruitment of bacteria from surrounding seawater. In contrast to a dense cover of the plastic surface with a diverse bacteria and phytoplankton community in the Atlantic samples, the samples from the North Sea were sparsely colonized with only single bacteria cells of Alteromonadaceae and other Gammaproteobacteria. Phytoplankton did not attach to the North Sea samples after two weeks. This restricted settlement of microbes might be due to rough weather and wave conditions during the early spring season. I could show with CLASI-FISH, which Bacteria dominated the 'Plastisphere' community, interactions among different Bacteria groups and between phytoplankton and Bacteria, and that the early stage biofilms on plastic can strongly differ in composition and distribution dependent on region and season.
Projektbezogene Publikationen (Auswahl)
- "A review of microscopy and comparative molecular-based methods to characterize 'Plastisphere' communities," Anal. Methods, vol. 9, no. 14, pp. 2132-2143, 2017
C. De Tender, C. Schlundt, L. I. Devriese, T. J. Mincer, E. R. Zettler, and L. A. Amaral-Zettler
(Siehe online unter https://doi.org/10.1039/c7ay00260b)
