Project Details
Projekt
Correlation between composition of microbial biofilms and weathering of exposed rock surfaces (biodeterioration) along a climatic and temporal gradient in Chile
Subject Area
Mineralogy, Petrology and Geochemistry
Term
from 2015 to 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 280662823
To test for a correlation between the taxonomic composition of microbial biofilms present on surfaces and inside of igneous hard rocks and the erosion (weathering) of the rock surfaces is the main subject of this project. The diversities of phototrophic (cyanobacteria, eukaryotic algae) as well as heterotrophic (other prokaryotes and microfungi) components of the biofilms will be determined comprehensively by using New Generation Sequencing (NGS). In addition, also cultures of phototrophic biofilm organisms will be studied. Changes in the biofilm composition will be analyzed along a climatic gradient of moisture and temperature. Therefore, biofilm and core drill samples will be collected from three different climatic zones in the Coastal Cordillera in Chile, i.e. the dedicated primary focus areas of the SPP 1803. From different successional stages of the biofilms and age determinations using 14C accelerator mass spectrometry a biological timescale will be established. Increased insights into the functionality of diversity changes of the biofilms will be achieved with high resolution imaging of rock hard part sections as well as biochemical analyses to trace signatures of microbial metabolic activity at the biofilm-rock interface. The spatial distribution and relative abundances of the organism groups within the biofilm successional stages will be examined using fluorescence in situ hybridization microcopy. Artificial hard rock surfaces will be exposed at the sampling sites for a parallel study of colonization by biofilms and erosion (weathering). To further develop the biological time scale of rock erosion detritus in the close vicinity of the rocks, i.e. rock particles with biofilms that already chipped of the rocks through deterioration, will be examined. Their biofilm microbial diversity may form the seeds for their colonization and, at an even later stage, the colonization of soil. This will provide an interface from rock deterioration to the development of microbial communities of the soil. To study the effects of biofilms on erosion and to establish a geological time scale Cosmogenic Nuclide Analyses (CNA) will be used. With CNA it will be tested 1) whether and if so to which extend there is a relationship between species (OTU) composition of the biofilms and rock erosion and 2) a gradual erosion of the surfaces (biodeterioration) is taking place. In the arid northern study area (Atacama Desert) also surfaces without detectable biofilm are expected. A comparison of concentrations of cosmogenic nuclides from samples with and without a biofilm will then assess whether biofilms exert a long-term control of surface deterioration.
DFG Programme
Priority Programmes
Subproject of
SPP 1803:
EarthShape: Earth Surface Shaping by Biota
Co-Investigators
Dr. Steven Binnie; Professor Dr. Rolf Daniel
