Project description:Gene expression microarrays were performed to investigate the molecular effects of exposure to environmental polluted groundwater. Zebrafish was treated with polluted waters collected from dumps located upstream and downstream a sanitary landfills. Gene expression profiling of zebrafish liver was analyzed after acute exposure to sampled waters.
Project description:Gene expression microarrays were performed to investigate the molecular effects of exposure to environmental polluted groundwater. Mice were treated with polluted waters collected from dumps located upstream and downstream a sanitary landfills. Gene expression profiling of mouse liver was analyzed after acute and chronic exposure to sampled waters.
Project description:This project contributes to the proteomic comparison of one asporogenic variant of emetic Bacillus cereus and its parental strain grown and harvested after 24 and 72h incubation in groundwater.
Project description:Pristine groundwater is a highly stable environment with microbes adapted to dark, oligotrophic conditions. Input events like heavy rainfalls can introduce excess particulate organic matter including surface-derived microbes into the groundwater, hereby creating a disturbance to the groundwater microbiome. Some of the translocated bacteria are not able to thrive in groundwater and will form necromass. Here, we investigated the effects of necromass addition to the microbial community in fractured bedrock groundwater, using groundwater mesocosms as model systems. We followed the uptake of 13C-labeled necromass by the bacterial and eukaryotic groundwater community quantitatively and over time by employing a combined protein and DNA stable isotope probing approach. Necromass was rapidly depleted in the mesocosms within four days, accompanied by a strong decrease of Shannon diversity and an increase of bacterial 16S rRNA gene copy numbers by one order of magnitude. Species of Flavobacterium, Massilia, Rheinheimera, Rhodoferax and Undibacterium dominated the microbial community within two days and were identified as key players in necromass degradation, based on a 13C incorporation of > 90% in their peptides. Their proteomes showed various uptake and transport related proteins, and many proteins involved in metabolizing amino acids. After four and eight days of incubation, autotrophic and mixotrophic groundwater species of Nitrosomonas, Limnohabitans, Paucibacter and Acidovorax increased in abundance, with a 13C incorporation between 0.5 and 23%. Our data point towards a very fast and exclusive uptake of labeled necromass by a few specialists followed by a concerted action of groundwater microorganisms, including autotrophs presumably fueled by released, reduced nitrogen and sulfur compounds generated during necromass degradation.
Project description:This project contributes to the proteomic comparison of one asporogenic variant of emetic Bacillus cereus and its parental strain grown in groundwater and harvested after 24 and 72h incubation.
Project description:Metagenome-assembled genomes (MAGs) have revealed the existence of novel bacterial and archaeal groups and provided insight into their genetic potential. However, metagenomics and even metatranscriptomics cannot resolve how the genetic potential translates into metabolic functions and physiological activity. Here, we present a novel approach for the quantitative and organism-specific assessment of the carbon flux through microbial communities with stable isotope probing-metaproteomics and integration of temporal dynamics in 13C incorporation by Stable Isotope Cluster Analysis (SIsCA). We used groundwater microcosms labeled with 13CO2 and D2O as model systems and stimulated them with reduced sulfur compounds to determine the ecosystem role of chemolithoautotrophic primary production. Raman microspectroscopy detected rapid deuterium incorporation in microbial cells from 12 days onwards, indicating activity of the groundwater organisms. SIsCA revealed that groundwater microorganisms fell into five distinct carbon assimilation strategies. Only one of these strategies, comprising less than 3.5% of the community, consisted of obligate autotrophs (Thiobacillus), with a 13C incorporation of approximately 95%. Instead, mixotrophic growth was the most successful strategy, and was represented by 12 of the 15 MAGs expressing pathways for autotrophic CO2 fixation, including Hydrogenophaga, Polaromonas and Dechloromonas, with varying 13C incorporation between 5% and 90%. Within 21 days, 43% of carbon in the community was replaced by 13C, increasing to 80% after 70 days. Of the 31 most abundant MAGs, 16 expressed pathways for sulfur oxidation, including strict heterotrophs. We concluded that chemolithoautotrophy drives the recycling of organic carbon and serves as a fill-up function in the groundwater. Mixotrophs preferred the uptake of organic carbon over the fixation of CO2, and heterotrophs oxidize inorganic compounds to preserve organic carbon. Our study showcases how next-generation physiology approach like SIsCA can move beyond metagenomics studies by providing information about expression of metabolic pathways and elucidating the role of MAGs in ecosystem functioning.
Project description:<p>Understanding biogeochemical conversions of dissolved organic matter (DOM) in aquifers is paramount for the effective management of groundwater supplies. On its passage through the critical zone, DOM is subject to biogeochemical conversions and therefore carries cross-habitat information useful for monitoring and predicting the stability of groundwater ecosystem services. Groundwater metabolomics assesses this information. However, challenges arise from insufficient knowledge on groundwater metabolite composition and dynamics, and the necessity to maintain analytical conditions for long-term monitoring. We explored fractured sedimentary bedrock by 5-year untargeted metabolomics monitoring for oxic perched and anoxic phreatic sites along a hillslope recharge area, to evaluate DOM as groundwater tracer. Dimension reduction by principal component analysis revealed that metabolome dissimilarities between distant wells coincide with transient cross-stratal flow indicated by groundwater levels and environmental tracers. The metabolome was highly variable lacking seasonal patterns, and did not segregate by geographic location of sampling wells thus ruling out surface vegetation or (agricultura) land use as driving factor. The metabolome time series provide detailed insights into subsurface responses to recharge dynamics. Metabolomics monitoring provides information on groundwater flows, and allows concluding about below ground ecology and water quality evolution, required to understand the impact of interannual wet-dry cycles.</p>