Improved methane mitigation potential and modulated methane cycling microbial communities in arable soil by compost addition.

The global atmospheric concentration of the potent greenhouse gas methane (CH) is rising rapidly, and agriculture is responsible for 30%-50% of the yearly CH emissions. To limit its global warming effects, strong and sustained reductions are needed. Sustainable agricultural management strategies, as the use of organic amendments like compost, have previously proven to have a potent CH mitigation effect in laboratory experiments.

Beyond methane consumption: exploring the potential of methanotrophic bacteria to produce secondary metabolites.

Microbial methane-consuming communities significantly impact biogeochemical processes and greenhouse gas emissions. In this study, we explored secondary metabolites produced by methane-oxidizing bacteria (MOB) and their ecological roles. We analyzed the volatile profiles of four MOB strains under controlled conditions and conducted a meta-analysis using high-quality genomes from 62 cultured MOB strains and 289 metagenome-assembled genomes to investigate their potential for producing secondary metabolites.

Exploring climate-related gut microbiome variation in bumble bees: An experimental and observational perspective.

Rising temperatures negatively affect bumble bee fitness directly through physiological impacts and indirectly by disrupting mutualistic interactions between bees and other organisms, which are crucial in determining species-specific responses to climate change. Gut microbial symbionts, key regulators of host nutrition and health, may be the Achilles' heel of thermal responses in insects. They not only modulate biotic interactions with plants and pathogens but also exhibit varying thermal sensitivity themselves.

Exploring modes of microbial interactions with implications for methane cycling.

Methanotrophs are the sole biological sink of methane. Volatile organic compounds (VOCs) produced by heterotrophic bacteria have been demonstrated to be a potential modulating factor of methane consumption. Here, we identify and disentangle the impact of the volatolome of heterotrophic bacteria on the methanotroph activity and proteome, using Methylomonas as model organism.

Temperature and livestock grazing trigger transcriptome responses in bumblebees along an elevational gradient.

Climate and land-use changes cause increasing stress to pollinators but the molecular pathways underlying stress responses are poorly understood. Here, we analyzed the transcriptomic response of workers to temperature and livestock grazing. Bumblebees sampled along an elevational gradient, and from differently managed grassland sites (livestock grazing vs unmanaged) in the German Alps did not differ in the expression of genes known for thermal stress responses.

Can flooding-induced greenhouse gas emissions be mitigated by trait-based plant species choice?

Intensively managed grasslands are large sources of the potent greenhouse gas nitrous oxide (NO) and important regulators of methane (CH) consumption and production. The predicted increase in flooding frequency and severity due to climate change could increase NO emissions and shift grasslands from a net CH sink to a source. Therefore, effective management strategies are critical for mitigating greenhouse gas emissions from flood-prone grasslands.

Organic Residue Amendments to Modulate Greenhouse Gas Emissions From Agricultural Soils.

Organic fertilizers have been shown to stimulate CH uptake from agricultural soils. Managing fertilizer application to maximize this effect and to minimize emission of other greenhouse gasses offers possibilities to increase sustainability of agriculture. To tackle this challenge, we incubated an agricultural soil with different organic amendments (compost, sewage sludge, digestate, cover crop residues mixture), either as single application or in a mixture and subjected it to different soil moisture concentrations using different amounts of organic amendments.

Explaining the doubling of N O emissions under elevated CO in the Giessen FACE via in-field N tracing.

Rising atmospheric CO concentrations are expected to increase nitrous oxide (N O) emissions from soils via changes in microbial nitrogen (N) transformations. Several studies have shown that N O emission increases under elevated atmospheric CO (eCO ), but the underlying processes are not yet fully understood. Here, we present results showing changes in soil N transformation dynamics from the Giessen Free Air CO Enrichment (GiFACE): a permanent grassland that has been exposed to eCO , +20% relative to ambient concentrations (aCO ), for 15 years.

Soil Conditions Rather Than Long-Term Exposure to Elevated CO Affect Soil Microbial Communities Associated with N-Cycling.

Continuously rising atmospheric CO concentrations may lead to an increased transfer of organic C from plants to the soil through rhizodeposition and may affect the interaction between the C- and N-cycle. For instance, fumigation of soils with elevated CO (CO) concentrations (20% higher compared to current atmospheric concentrations) at the Giessen Free-Air Carbon Dioxide Enrichment (GiFACE) sites resulted in a more than 2-fold increase of long-term NO emissions and an increase in dissimilatory reduction of nitrate compared to ambient CO (CO). We hypothesized that the observed differences in soil functioning were based on differences in the abundance and composition of microbial communities in general and especially of those which are responsible for N-transformations in soil.

Potential NO Emissions from the Tanks of Bromeliads Suggest an Additional Source of NO in the Neotropics.

We studied the propensity of the tank bromeliad Werauhia gladioliflora to emit the greenhouse gas nitrous oxide (NO) at current and at increased N deposition levels in the range of predicted future scenarios. Potential production rates and net accumulation of NO from tank substrate corresponded to N availability. NO was produced in excess at all N levels due to a low level of NO reductase activity which agreed well with a low abundance of NO reducers compared to nitrite reducers.

pH-driven shifts in overall and transcriptionally active denitrifiers control gaseous product stoichiometry in growth experiments with extracted bacteria from soil.

Soil pH is a strong regulator for activity as well as for size and composition of denitrifier communities. Low pH not only lowers overall denitrification rates but also influences denitrification kinetics and gaseous product stoichiometry. N2O reductase is particularly sensitive to low pH which seems to impair its activity post-transcriptionally, leading to higher net N2O production.

Impact of Land Use Management and Soil Properties on Denitrifier Communities of Namibian Savannas.

We studied potential denitrification activity and the underlying denitrifier communities in soils from a semiarid savanna ecosystem of the Kavango region in NE Namibia to help in predicting future changes in N(2)O emissions due to continuing changes of land use in this region. Soil type and land use (pristine, fallow, and cultivated soils) influenced physicochemical characteristics of the soils that are relevant to denitrification activity and N(2)O fluxes from soils and affected potential denitrification activity. Potential denitrification activity was assessed by using the denitrifier enzyme activity (DEA) assay as a proxy for denitrification activity in the soil.

Impact of short-term storage temperature on determination of microbial community composition and abundance in aerated forest soil and anoxic pond sediment samples.

Sampling strategy is important for unbiased analysis of the characteristics of microbial communities in the environment. During field work it is not always possible to analyze fresh samples immediately or store them frozen. Therefore, the effect of short-term storage temperature was investigated on the abundance and composition of bacterial, archaeal and denitrifying communities in environmental samples from two different sampling sites.