Biology subjects

Pancost, R. D.

Publications and source records attributed to Pancost, R. D..

3 recordsLinked to original sources

bioRxiv2025

Structure and function of the global peatland microbiome

Peatlands are vital long-term carbon sinks but also sources of trace greenhouse gases, with the balance largely governed by microbial processes. However, the structure and function of peatland microbial communities are currently poorly characterised beyond the local scale, limiting our understanding of their response to climate change. Here, we present a large-scale analysis of the peatland prokaryotic microbiome by leveraging a curated dataset of 109 publicly available metagenomes from 20 near-natural peatland sites worldwide. Despite limitations in the publicly available data, including geographic coverage and sampling depth, our analysis indicates that dominant vegetation and peatland type are the strongest predictors of peatland microbiome taxonomy and function. We show that obligate hydrogenotrophic methanogens of the family Bog-38, previously reported to be prevalent in diverse high methane-flux habitats, are abundant in northern peatlands but occur only at low abundance in tropical peatlands, suggesting a limited contribution to methane cycling in these ecosystems. In contrast to northern peatlands, the tropical peatland microbiome exhibits a broad metabolic potential for multiple key peatland biogeochemical processes, including methanogenesis and denitrification, across all depths. Intriguingly, we observe an impaired potential for complete denitrification in a significant proportion of the northern fen metagenomes, with potential implications for nitrous oxide emissions as a greenhouse gas. Overall, our study uncovers large-scale patterns and ecological drivers of the peatland prokaryotic microbiome based on existing metagenomic data, enhancing our understanding of its response to climate change and highlighting major data gaps for future research.

microbiology↗

bioRxiv2022

The production of diverse brGDGTs by an Acidobacterium allows a direct test of temperature and pH controls on their distribution

Microbial lipid biomarkers preserved in geological archives can be used to explore past climate changes. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are unique bacterial biomarkers that have been used as molecular tools for the quantitative determination of terrestrial temperatures and the pH of depositional environments over a range of geological timescales. However, the exact biological source organisms - especially of the entire suite of brGDGTs found in the environment - remains unclear; by extension, so do the mechanisms that govern these proxies. Here, we identified a brGDGT-producing strain Candidatus Solibacter usitatus Ellin6076, by identifying archaeal tetraether synthase homologs in bacterial genomes. This strain synthesizes diverse brGDGTs, including regular C5-methylated and cyclic brGDGTs, and brGDGTs comprise up to 66% of the major lipids, far exceeding the proportions found in previous studies. The degree of C5-methylation in cultured strain Ellin6076 is primarily determined by temperature, whereas cyclization appears to be influenced by multiple factors. Consequently, culture-derived paleoclimate indices are in agreement with the global soil-derived MBT5ME (methylation index of C5-methyl brGDGTs) proxy for temperature but not the CBT5ME (cyclization index of C5-methyl brGDGTs) proxy for pH. Our findings provide important insights from a physiological perspective into the underlying mechanism of brGDGT-based proxies. Significance StatementBranched glycerol dialkyl glycerol tetraethers (brGDGTs) are biomarkers widely used for the quantitative estimation of past climatic changes due to their ubiquitous occurrence in the environment and the relationships between their distributions and temperature and pH. However, the ecophysiology of brGDGT-producing bacteria and the mechanistic basis for brGDGT-based climate proxies remain unknown. Here, we identify a brGDGT-producing Acidobacterium and present a physiological study of brGDGTs in response to cultivation variables, which provides pivotal insights into how brGDGT producers modulate methylation and cyclization under different culturing conditions. Our study represents a significant advancement in understanding the physiological role of lipid structures in microbial adaptation and helps us interpret the relationships between brGDGT-based proxies and environmental conditions of the geological environment.

microbiology↗

bioRxiv2018

Extensive transfer of membrane lipid biosynthetic genes between Archaea and Bacteria

One of the key differences between Bacteria and Archaea are their canonical membrane phospholipids, which are synthesized by distinct biosynthetic pathways with non-homologous enzymes. This \"lipid divide\" has important implications for the early evolution of cells and the type of membrane phospholipids present in the last universal common ancestor (LUCA). One of the main challenges in studies of membrane evolution is that the key biosynthetic genes are ancient and their evolutionary histories are poorly resolved. This poses major challenges for traditional rooting methods because the only available outgroups are distantly related. Here, we address this issue by using the best available substitution models for single gene trees, by expanding our analyses to the diversity of uncultivated prokaryotes recently revealed by environmental genomics, and by using two complementary approaches to rooting that do not depend on outgroups. Consistent with some previous analyses, our rooted gene trees support extensive inter-domain horizontal transfer of membrane phospholipid biosynthetic genes, primarily from Archaea to Bacteria. They also suggest that the capacity to make archaeal-type membrane phospholipids was already present in LUCA.

evolutionary biology↗