Biology subjects

Dippold, M. A.

Publications and source records attributed to Dippold, M. A..

4 recordsLinked to original sources

bioRxiv2025

Effect of biogel C addition on biochar degradation and microbial activities

Biochar contributes to long-term soil carbon stabilization (C) by acting both as a stable carbon pool and as a sorbent for labile compounds. Biogels from roots and microbes are known to form persistent surface coatings with soil sorbents, where they host microbial hotspots. Yet research has mainly focused on their interactions with minerals. The interactive effects of biogels and biochar on soil carbon dynamics remain largely unexplored. This study aimed to assess the effects of biogel coatings on fresh and aged biochar, particularly under drought, with a focus on biochar degradation and microbial responses. We conducted a three-factorial soil incubation study to examine the effects of fresh and aged biochar, with or without biogel amendment, under two moisture levels (30% and 70% water holding capacity, WHC). Using 14C labelled biochar, we quantified biochar degradation and biochar- induced priming effects by measuring 14CO2respiration, microbial biomass carbon (MBC) and its 14C incorporation, hydrolytic and oxidative enzyme activities, and changes in biochar surface area. Mucilage strongly enhanced microbial incorporation of biochar-derived C, specifically from aged biochar under drought conditions, while the opposite effect was observed in soils amended with fresh biochar. This demonstrates the greater microbial accessibility of aged biochar surfaces and limited use of fresh biochar due to inaccessibility of the hydrophobic surfaces, and in consequence the preference for more easily accessible C sources. Additionally, mucilage significantly reduced the Michaelis Menten constant (Km) of {beta}-glucosidase by up to 58% in soils amended with aged biochar under drought. This indicates that under these conditions, the interaction of the aged biochar with the biogel may have created a unique habitat requiring specific enzyme systems with higher affinity. Our findings highlight the role of mucilage in regulating microbial surface access and thus the decomposition of biochar, particularly under moisture- limited conditions. The synergy between aged biochar and biogels provides a promising new perspective to further enhance biochar-based drought mitigation, specifically for managing microbial activity in drought-prone soils.

ecology↗

bioRxiv2025

Cover crop root channels promote bacterial adaptation to drought in the maize rhizosphere

BackgroundIncreasing drought frequency poses a significant threat to agricultural productivity. A promising strategy to enhance crop resilience against drought is the utilisation of root channels left by winter cover crops, which can improve access to subsoil water and nutrients for subsequent cash crops like maize (Zea mays L.). The impact of drought on bacterial communities inhabiting these root channels remains largely unknown. Here, we investigated drought-induced shifts in maize rhizosphere bacterial communities and their functional adaptation in cover crop root channels across three soil types in northern Germany (Luvisol, Podzol, and Phaeozem). ResultsUsing a multi-omics approach (16S rRNA gene amplicon sequencing, qPCR, and metaproteomics), we identified significant taxonomic and functional responses to drought. A rise in the abundance of K-strategist bacterial communities indicate a shift towards stress-tolerant populations with drought. Under drought stress, the relative abundances of Acidobacteriota, Actinomycetota, Planctomycetota, and Pseudomonadota increased, while Chloroflexota, Methylomirabilota, Ca. Patescibacteria, and Verrucomicrobiota declined. Functional analyses revealed that drought-stressed aerobic taxa among the Pseudomonadota and Verrucomicrobiota upregulated the glyoxylate cycle, potentially enhancing carbon and energy conservation, and increased antioxidant defences (catalase-glutathione peroxidase and methionine cycle-transsulfuration pathway). These drought-mitigating strategies were especially pronounced in root channels formed by Brassicaceae and Poaceae cover crops in the Luvisol and Podzol soils. ConclusionsThese findings demonstrate the functional plasticity of rhizosphere bacterial communities in reused root channels in response to drought, highlighting the potential to leverage microbiome-mediated resilience for agricultural practices. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/651044v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@7c3f69org.highwire.dtl.DTLVardef@127182forg.highwire.dtl.DTLVardef@1a4bb61org.highwire.dtl.DTLVardef@9f7c4_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Environmental versus litter traits as drivers of microbial decomposer functions

Plant litter decomposition is a key ecosystem process with significant implications for global carbon cycling, soil fertility and plant productivity. Given that microbial decomposers are the main players in the decomposition process, it is surprising how little is known about their functional diversity in different habitats or their ability to respond to environmental changes. To fill this knowledge gap, we conducted a litterbag decomposition experiment along a pronounced climate and vegetation gradient in the Chilean Coastal Cordillera (26{degrees}S to 38{degrees}S), ranging from hyper-arid to temperate, using mixtures of four plant species, native to the respective ecosystems. We analyzed potential decomposition functions of bacterial and fungal litter communities along with their biotic (litter traits) and abiotic (meteorological conditions and soil properties) environments, to determine the relative importance of these environmental factors for microbial community functioning. We also tested the impact of the functional diversity of the decomposer communities (i.e., the diversity of decomposition related functions) on litter mass loss. Functional composition was related most strongly to the temporal variation of precipitation and radiation, explaining about 19 % and 6 % of variation in bacteria and fungi, respectively. In contrast, functional diversity was quite strongly related to litter chemical traits (C:N, C:P, tannins, phenols). Litter mass loss after six months of decomposition was not correlated to the functional diversity of decomposer communities but increased with the presence of habitat generalists like Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes. Taken together, these results highlight i) the interplay between abiotic factors and chemical litter traits on litter microbial functions and functional diversity and ii) the importance of microbial generalists for litter decomposition across different ecosystems. These results enhance our ability to predict changes in microbial decomposer communities and litter decomposition under future climate-change scenarios.

ecology↗

bioRxiv2022

Intracellular carbon storage by microorganisms is an overlooked pathway of biomass growth

The concept of microbial biomass growth is central to microbial carbon (C) cycling and ecosystem nutrient turnover. Growth is usually assumed to occur by cellular replication, despite microorganisms capacity to increase biomass by synthesizing storage compounds. Here we examined whether C storage in triacylglycerides (TAGs) and polyhydroxybutyrate (PHB) contribute significantly to microbial biomass growth, under contrasting conditions of C availability and complementary nutrient supply. Together these compounds accounted for 19.1 {+/-} 1.7% to 46.4 {+/-} 8.0% of extractable soil microbial biomass, and revealed up to 279 {+/-} 72% more biomass growth than observed by a DNA-based method alone. Even under C limitation, storage represented an additional 16 - 96% incorporation of added C into microbial biomass. These findings encourage greater recognition of storage synthesis and degradation as key pathways of biomass change and as mechanisms underlying resistance and resilience of microbial communities.

ecology↗