Project Details
Projekt
Microbial communities: Diversity and metabolic function
Applicants
Dr. Julius Degenhardt; Privatdozent Dr. Bert Engelen
Subject Area
Oceanography
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 431491505
The aim of DynaDeep is to unravel the functionality and relevance of marine-terrestrial interactions below high-energy beaches. We propose the deep subsurface to act as a dynamic bioreactor and unique microbial habitat affecting elemental net fluxes to the sea. To reach this goal, seven subprojects will cooperate in joint field campaigns, shared sampling approaches as well as experimental work and use mathematical models in an integrative approach. Subproject P5 builds on the results of Phase 1 and will investigate microbial adaptations to frequently changing redox conditions coupled with apparent carbon limitation in the deeper parts of the STE (“hot spots“). We will broaden our investigations on our core-field site Spiekeroog to obtain long-term results and include specific aspects like the role of stormfloods (“hot moments“). We further extend our investigation to two additional validation sites (Truc Vert, De Panne) to test to what extent the Spiekeroog results can be generalized for high-energy beaches. We hypothesize that i) The niche separation between sediment-attached and interstitial microbial communities is a common feature of STEs, ii) Recalcitrant DOM within the deep STE is altered by microbial activity during stable conditions while DOM released by redox shifts under transient conditions sustains microbial communities and boosts activity on short time scales, and iii) The high precentage of amplicon frequencies of ultra-small Nanoarchaeota and members of the CPR indicate a natural enrichment in the porewaters and leads to an in-depth analysis of their specific lifestyles within the aquifer. During joint field campaigns, P5 will determine cell numbers and community patterns of 16S rRNA genes and gene transcripts in sediments and corresponding porewaters. Selected sediment horizons will be target for metagenome analyses. The metabolic response to changing redox conditions and resulting biogeochemical transformations of DOM will be followed in controlled laboratory experiments. All microbiological findings of P5 will be related to the respective geochemical parameters to unravel the coupling of microbial transformations to DOM composition (subproject P3) as well as conversion of redox-sensitive elements (subproject P4). Information on microbial distribution patterns and their metabolic network will be shared with subproject P2 to specifically investigate heterotrophic (P5) and autotrophic processes (P2).
DFG Programme
Research Units
