Applicant

Professor Dr. Michael Friedrich
Universität Bremen
Fachbereich 02 - Biologie und Chemie
Arbeitsgruppe Mikrobielle Ökophysiologie
Leobener Straße 
28359 Bremen

Project description

Climate-based warming has affected the western Antarctic Peninsula (WAP) strongly over the last 50 years. At our study site, Potter Cove (King George Island), glacial melting has resulted firstly, in the release of large amounts of suspended material into the cove, and secondly, in newly ice-free areas for colonization by seaweeds. These environmental changes have stark consequences for the entire food web of the cove. Large amounts of dislodged seaweeds end up in the seabed of the cove, and can render even the top sediment layer anaerobic driven by degradation processes. The first step in the anaerobic degradation is hydrolysis of polymeric organic matter and subsequent fermentation of monomers by primary fermenting microorganisms. In contrast to our knowledge about the canonical sulfate-reducing microorganisms, responsible for as much as 50% of anaerobic organic matter oxidation in marine sediments, little is known about the fermenting microorganisms, especially in Antarctic marine sediments. Remarkably, only with the formation of fermentation products, life of sulfate- and iron reducing microorganisms will become feasible, which we have identified previously as keystone taxa in Potter Cove sediments. The main aim of our project is to elucidate the ecology of fermenting microorganisms in Antarctic marine sediments; they hold a keystone function in the ecosystem in starting the anaerobic breakdown of polymeric organic matter, yet their identity in Antarctic sediments and controls of their activity are barely understood. We will concentrate on 1) identifying keystone fermenting microbial populations, (2) determining their distribution, (3) abundance, and (4) activity in anoxic layers of the Antarctic coastal sediments. In our project we will use sediment from cove sites that are hot spots of environmental change with varying geochemical background in iron oxide, sulfidogenic sites and organic matter content including carbohydrates, a prime substrate class for fermenting microorganisms. The geochemical data will be linked to community composition by next generation 16S rRNA gene sequencing and qPCR quantification using newly obtained samples. Keystone fermenting microorganisms will be identified by cutting-edge RNA based stable isotope probing incubations with 13C-labelled polymeric organic matter. For predicting future scenarios, factors will be studied that are potentially controlling fermenting microorganisms including temperature increase, and extracellular electron sinks (in the form of iron oxides) that are plentiful in cove sediments by using incubation experiments. Our project will allow clarifying, which fermenting microorganisms are present in Potter Cove sediments, provide as keystone taxa indispensable services for the anaerobic microbial food chain, and thus, contribute to a better understanding of polar processes and mechanisms.

DFG Programme Infrastructure Priority Programmes

Term since 2026