Biology subjects

Petters, S.

Publications and source records attributed to Petters, S..

4 recordsLinked to original sources

bioRxiv2024

The methane-cycling microbiome in intact and degraded permafrost soils of the pan-Arctic

The methane-cycling microbiomes in Arctic permafrost-affected soils play crucial roles in the production and consumption of this important greenhouse gas. However, little is known about the distributions of Arctic methanogens and methanotrophs across the regional scale and along the vertical soil profile, as well as their responses to the widespread permafrost thaw. Using a unique sample set from nine different locations across the pan-Arctic, we identified methanogen and methanotroph phylotypes in 729 datasets of 16S rRNA gene amplicons. In 621 samples of intact permafrost soils across the pan-Arctic, only 22 methanogen and 26 methanotroph phylotypes were identified. Relative abundances of both functional groups varied significantly between sites and soil horizons. Only four methanogen phylotypes were detected at all locations, with the hydrogenotrophic Methanobacterium lacus dominating. Remarkably, the permafrost soil methane filter was almost exclusively comprised of a few phylotypes closely related to the obligate methanotrophic species Methylobacter tundripaludum. In degraded permafrost sites in Alaska, M. tundripaludum also dominated the methanotroph microbiome in the wet site. However, in dry, water-drained former permafrost site, Methylocapsa phylotypes, closely related with the atmospheric methane oxidizing bacteria, were exclusively found and dominant, indicating a massive restructuring of the methanotroph guild that consequently resulted in functional changes from a soil methane filter to an atmospheric methane sink. This study provides first insights into the identity and intricate spatial distribution of methanotrophs and methanogens in permafrost soils at a pan-Arctic scale and their responses to different water status after permafrost degradation. These findings point towards a few key microbes particularly relevant for future studies on Arctic CH4 dynamics in a warming climate and that under future dry conditions more atmospheric CH4 uptake in Arctic upland soils might happen.

microbiology↗

bioRxiv2023

The bioreactor microbiome of mass cultivated marine diatoms for industrial carbon capture and utilization

Marine microalgae are a promising innovation platform for carbon capture and utilization (CCU) biotechnologies to mitigate industrial greenhouse gas emissions. However, industrial-scale cultivation of algal mono-cultures is challenging and often unscalable. Non-axenic microalgae in large semi-open photobioreactors lead to the co-cultivation of diverse microbial communities. There is limited knowledge about the "bioreactor ecology" involving microalgae interacting with the microbiome and its subsequent impact on process stability and productivity. In this study, we describe the semi-continuous industrial mass cultivation of the cold-adapted marine diatom, Porosira glacialis UiT201, by investigating the prokaryotic and microeukaryotic (phytoplankton and heterotrophic protist) communities. Data were collected in two consecutive time series experiments, representing the initiation and operation of an preindustrial scale CCU photobioreactor (300,000 liters). The first experiment experienced a culture "crash" of the focal strain after 39 days, while the second culture remained stable and "healthy" for 60 days. The results highlight that this mass cultivation system represents a unique industrial marine microbial ecosystem. The succession of the prokaryotic community was primarily driven by species replacement, indicating turnover due to selective bioreactor conditions and/or biological interactions. Nonetheless, the bioreactor consistently harbors a recurring and abundant core microbiome, suggesting that the closely associated bacterial community is influenced by microalgae-specific properties and can endure a dynamic and variable environment. The observed culture collapse of P. glacialis coincided with changes in the core microbiome structure and different environmental growth conditions compared to the stable and "healthy" experiment. These findings imply that cohabiting microbial taxa within industrial microalgae cultivation likely play a critical role in stabilizing the conversion of industrial CO2 into marine biomass, and changes in community structure serve as an indicator of process stability.

microbiology↗

bioRxiv2022

Microbial community dynamics during a harmful Chrysochromulina leadbeateri bloom

A harmful algae bloom occurred in late spring 2019 across multiple, interconnected fjords and bays in northern Norway. The event was caused by the haptophyte Chrysochromulina leadbeateri and led to severe fish mortality at several salmon aquaculture facilities. This study reports on the spatial and temporal succession dynamics of the holistic marine microbiome associated with this bloom by relating all detectable 18S and 16S rRNA gene ASVs to the relative abundance of the C. leadbeateri focal taxon. A k-medoids clustering enabled inferences on how the causative focal taxon co-bloomed with diverse groups of bacteria and microeukaryotes. These co-blooming patterns showed high temporal variability and were distinct between two geographically separated time series stations during the regional harmful algae bloom. The distinct blooming patterns observed with respect to each station were poorly connected to environmental conditions suggesting that other factors, such as biological interactions, may be at least as important in shaping the dynamics of this type of harmful algae bloom. A deeper understanding of microbiome succession patterns during these rare but destructive events will help guide future efforts to forecast deviations from the natural bloom cycles of the northern Norwegian coastal marine ecosystems that are home to intensive aquaculture activities.

microbiology↗

bioRxiv2018

The soil microbial foodweb revisited with metatranscriptomics - predatory Myxobacteria as keystone taxon?

Trophic interactions in the microbial food web of soils are crucial for nutrient and carbon cycling. Traditionally, protozoa are considered the major micropredators of bacteria in soil. However, some prokaryotes, such as Myxobacteria and Bdellovibrio are also famous for bacterivorous life style. Until recently, it was impossible to assess the abundance of pro- and eukaryotic micropredators in soils simultaneously. Using a metatranscriptomic three-domain profiling of small subunit ribosomal RNA we investigated the abundance of bacterivores in 28 datasets from eleven European mineral and organic soils of different climatic zones. In all soils, Myxobacteria comprised a significant proportion from 4 - 19% of prokaryotic 16S rRNA transcripts and more than 60% of all bacterivores in most soils. Haliangiaceae and Polyangiaceae were most abundant, while the name-giving Myxococcaceae were barely present. Other bacterial predators like Bdellovibrio were low abundant. Also Protozoan micropredator 18S rRNA transcripts, e.g. from Cercozoa, Amoebozoa and Ciliophora, were on average less abundant, especially in mineral soils. Nematodes were even less abundant. In addition, we applied a longitudinal approach to identify bacterivores during beech litter colonisation. Here, Myxobacteria showed prey-dependent, protozoa-like community dynamics during colonisation. Thus, their broad prey range and high abundance suggests a major influence of Myxobacteria on structuring the prokaryotic community composition in soil, and might warrant their classification as keystone taxon. Our results suggest the presence of an ecologically important \"bacterial loop\" in soil food webs, independent of protozoa and nematodes.

microbiology↗