Source Themes

Kinetics and Identities of Extracellular Peptidases in Subsurface Sediments of the White Oak River Estuary, North Carolina

Anoxic subsurface sediments contain communities of heterotrophic microorganisms that metabolize organic carbon at extraordinarily slow rates. In order to assess the mechanisms by which subsurface microorganisms access detrital sedimentary organic …

Uncultured microbial phyla suggest mechanisms for multi-thousand-year subsistence in Baltic Sea sediments

Energy-starved microbes in deep marine sediments subsist at near-zero growth for thousands of years, yet the mechanisms for their subsistence are unknown because no model strains have been cultivated from most of these groups. We investigated Baltic …

Characterization of the Interactive Effects of Labile and Recalcitrant Organic Matter on Microbial Growth and Metabolism

Geochemical models typically represent organic matter (OM) as consisting of multiple, independent pools of compounds, each accessed by microorganisms at different rates. However, recent findings indicate that organic compounds can interact within …

Understanding Electrochemically Activated Persulfate and Its Application to Ciprofloxacin Abatement

This study offers insight into the roles anodic and cathodic processes play in electrochemically activated persulfate (EAP) and screens EAP as a viable technique for ciprofloxacin degradation in wastewater. Sulfate radical formation at a boron-doped …

Potential Activities of Freshwater Exo- and Endo-Acting Extracellular Peptidases in East Tennessee and the Pocono Mountains

Proteins constitute a particularly bioavailable subset of organic carbon and nitrogen in aquatic environments but must be hydrolyzed by extracellular enzymes prior to being metabolized by microorganisms. Activities of extracellular peptidases …

Sequential bioavailability of sedimentary organic matter to heterotrophic bacteria

Aquatic sediments harbour diverse microbial communities that mediate organic matter degradation and influence biogeochemical cycles. The pool of bioavailable carbon continuously changes as a result of abiotic processes and microbial activity. It …

Evidence for the Priming Effect in a Planktonic Estuarine Microbial Community

The “priming effect,” in which addition of labile substances changes the remineralization rate of recalcitrant organic matter, has been intensively studied in soils, but is less well-documented in aquatic systems. We investigated the extent to which …

Substrate specificity of aquatic extracellular peptidases assessed by competitive inhibition assays using synthetic substrates

The identities and biochemical properties of extracellular enzymes present in natural environments are poorly constrained. We used a series of competitive inhibition experiments with samples from a freshwater environment (the Tennessee River at …

New aminopeptidase from “microbial dark matter” archaeon

Marine sediments host a large population of diverse, heterotrophic, uncultured microorganisms with unknown physiologies that control carbon flow through organic matter decomposition. Recently, single-cell genomics uncovered new key players in these …

Extracellular enzymes in terrestrial, freshwater, and marine environments: Perspectives on system variability and common research needs

Extracellular enzymes produced by heterotrophic microbial communities are major drivers of carbon and nutrient cycling in terrestrial, freshwater, and marine environments. Although carbon and nutrient cycles are coupled on global scales, studies of …