Biology subjects

Glombitza, C.

Publications and source records attributed to Glombitza, C..

3 recordsLinked to original sources

bioRxiv2024

Drivers of methane-cycling archaeal abundances, community structure, and catabolic pathways in continental margin sediments

Marine sediments contain Earths largest reservoir of methane, with most of this methane being produced and consumed in situ by methane-cycling archaea. While numerous studies have investigated communities of methane-cycling archaea in hydrocarbon seeps and sulfate-methane transition zones, little is known about how these archaea change from the seafloor downward in the far more common diffusion-dominated marine sediments. Focusing on four continental margin sites of the North Sea-Baltic Sea transition, we here investigate the in situ drivers of methane-cycling archaeal community structure and metabolism based on geochemical and stable carbon-isotopic gradients, functional gene (mcrA) copy numbers and phylogenetic compositions, as well as thermodynamic calculations. We observe major vertical and lateral changes in community structure that largely follow changes in organic matter reactivity and content, sulfate concentration, and bioturbation activity. While methane-cycling archaeal communities in bioturbation and sulfate reduction zones are dominated by known methyl-dismutating taxa within the Methanosarcinaceae and putatively CO2-reducing Methanomicrobiaceae, the communities change toward dominance of known methane-oxidizing taxa (ANME-2a-b, ANME-2c, ANME-1a-b) in sulfate-methane transitions. Underlying methanogenesis zones were characterized by a change toward mainly physiologically uncharacterized groups, including ANME-1d and several new genus-level groups of putatively CO2-reducing Methanomicrobiaceae and methyl-reducing Methanomassiliicoccales. Notably, group-specific increases in mcrA copy numbers by 2 to 4 orders of magnitude from the sulfate reduction zone into the sulfate-methane transitions or methanogenesis zones indicate the thriving of several major methane-cycling archaeal taxa. Together our study provides insights into the community and pathway shifts vertically along the geochemical gradients and horizontally along the different sedimentary settings and their underlying drivers in continental margin sediments.

ecology↗

bioRxiv2024

The effect of a short oxygen exposure period on algal biomass degradation and methane formation in eutrophic and oligotrophic lake sediments

Eutrophication is suggested to enhance lacustrine methane emissions, due to enhanced sedimentary decomposition rates of algal biomass, and more frequent occurrence of water column anoxia. We investigated methane emissions from sediments originating from both a eutrophic and oligotrophic lake, and tested the effect of additional algal C inputs. Additionally, we investigated the effect of a pulse supply of oxygen, a mediating measure that is currently being used in the investigated eutrophic lake. Our results show a large legacy effect of eutrophication, but the methane release from new algal biomass additions was the same, although the process proceeded more rapidly in the eutrophic sediments. A short, 3-week pulse of oxygen lowered the emitted methane from both types of sediments by 50%, not only reducing the emissions of algal biomass additions, but also reducing methane emissions from the experiments without fresh organic matter inputs. This effect was relatively long-lasting: its effects were visible for several weeks after anoxic conditions were re-established, making it a potentially interesting measure to lower methane emissions over a longer period. Volatile fatty acid concentrations in the sediments were lowered due to oxygen exposure. Both the methanogenic and methanotrophic community composition showed surprisingly little response to the oxygen or algal biomass pulses. Overall, our results show that providing sediments with a brief pulse of oxygen following an algal bloom event, could strongly mediate the methane emissions following such an event. Such measures could be considered by policy makers to limit greenhouse gas emissions from managed lakes.

molecular biology↗

bioRxiv2020

Anaerobic microbial degradation of protein and lipid macromolecules in subarctic marine sediment

Microorganisms in marine sediments play major roles in marine biogeochemical cycles by mineralizing substantial quantities of organic matter from decaying cells. Proteins and lipids are abundant components of necromass, yet microorganisms that degrade them remain understudied. Here, we revealed identities, trophic interactions and genomic features of microorganisms that degraded 13C-labelled proteins and lipids in cold anoxic microcosms with sulfidic subarctic marine sediment. Supplemented proteins and lipids were rapidly fermented to various volatile fatty acids within five days. DNA-stable isotope probing (SIP) suggested Psychrilyobacter atlanticus was an important primary degrader of proteins, and Psychromonas members were important primary degraders of both proteins and lipids. Closely related Psychromonas populations, as represented by distinct 16S rRNA gene variants, differentially utilized either proteins or lipids. DNA-SIP also showed 13C-labeling of various Deltaproteobacteria within ten days, indicating trophic transfer of carbon to putative sulfate-reducers. Metagenome-assembled genomes revealed the primary hydrolyzers encoded secreted peptidases or lipases, and enzymes for catabolism of protein or lipid degradation products. Psychromonas were prevalent in diverse marine sediments, suggesting they are important players in organic carbon processing in situ. Together, this study provides an improved understanding of the metabolic processes and functional partitioning of necromass macromolecules among microorganisms in the seafloor.

microbiology↗