P5: Microbial communities: Diversity and metabolic function
Subproject P5 will identify variations in microbial community structures and their metabolic response to the dynamic changes in electron acceptor availability and electron donor quality within the subsurface of high-energy beaches. We hypothesize that these dynamically changing environmental conditions lead to (i) highly adapted microbial communities, composed of generalists and (ii) to a rapid metabolic response, reflected in their metatranscriptome. During the joint field campaigns, P5 will determine cell numbers and community patterns of 16S rRNA genes and transcripts in sediments and corresponding porewaters. Selected sediment horizons will be target for high-resolution metagenome and metatranscriptome analyses. The metabolic response to changing environmental conditions and resulting biogeochemical transformations 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 and fractionation of redox-sensitive elements (subprojects P2 and P4). Information on microbial distribution patterns and their metabolic network will help to calibrate the field scale and reactive transport model for the subsurface of high-energy beaches (subprojects P1 and P6).