Project description:In recent years, sediments from cave environments have provided invaluable insights into ancient hominids, as well as past fauna and flora. Unfortunately, locations with favourable conditions for ancient DNA (aDNA) preservation in sediments are scarce. In this study we analysed a set of samples obtained from sediments adhered to different human skeletal elements, originating from Neolithic to Medieval sites in England, and performed metagenomics and metaproteomics analysis. From them, we were able to reconstruct a partial human genome. The genetic profile of those human sequences matches the one recovered from the original skeletal element. Additionally, aDNA sequences matching the genomes of endogenous gut and oral microbiome bacteria were identified. We also found the presence of genetic sequences corresponding to animals and plants. In particular we managed to retrieve the partial genome and proteome of a Black Rat (Rattus rattus), sharing close genetic affinities to other medieval Rattus rattus. Our results demonstrate that material usually discarded, as it is sediments adhering to human remains, can be used to get a glimpse of the environmental conditions at the time of the death of an individual.
Project description:Bacteria are known to adhere to surfaces via self-produced extracellular polymeric substances organized as biofilms. In subsurface areas with low oxygen, limited nutrients, and toxic contaminants, biofilms are crucial for microbial survival and persistence. However, the relationship between biofilm formation and survival in such environments is not well-documented. At the Oak Ridge Reservation Field Research Center (ORRFRC), we observed a high abundance of Rhodanobacter species in conditions with elevated nitrate, metals, organics, and nitric acid. This study investigated the role of biofilm formation in their survival and the underlying molecular mechanisms in diverse geochemical niches. We examined sixteen phylogenetically diverse Rhodanobacter strains for biofilm formation under varying nutrient, pH, and nitrate conditions. Our findings indicate that biofilm formation is a strain-specific phenotype, correlating with environmental stresses, especially in low pH and nitrate conditions. Comparative genomic analysis revealed unique traits in the high biofilm-forming FW021-MT20 strain, such as the absence of flagella and chemotaxis genes and the presence of unique secretion system VI genes, as supported by pangenomic results. Additional tests on biofilm formation in response to field-relevant metals highlighted increased biofilm formation under aluminum stress in strains typically exhibiting weaker biofilm capabilities. Further investigation using RB-Tnseq, proteomics, and TEM indicated flagellar loss under aluminum stress, linked to increased cyclic AMP and di-GMP levels. Our results shed light on the adaptive strategies of Rhodanobacter strains in subsurface environments, suggesting genetic factors linked to biofilm formation and metal stress tolerance, thereby enhancing our understanding of microbial survival under environmental stress.
Project description:Prolific heterotrophic biofilm growth is a common occurrence in airport receiving streams containing deicer and anti-icer runoff. This study investigated relations of heterotrophic biofilm prevalence and community composition to environmental conditions at stream sites upstream and downstream of Milwaukee Mitchell International Airport in Milwaukee, WI, during two deicing seasons (2009–2010 and 2010–2011). Modern genetic tools (such as microarray) have not previously been applied to biofilm communities in this type of setting. We used microarray results to characterize biofilm community composition as well as the response of the biofilm community to environmental factors (i.e., organic content (using chemical oxygen demand concentration) and temperature).