Biology subjects

Burrichter, A. G.

Publications and source records attributed to Burrichter, A. G..

5 recordsLinked to original sources

bioRxiv2026

Oral Fumarate-based drugs alter gut microbiota species via cysteine succination

Mono- and dimethyl fumarates are oral fumarate esters widely prescribed for relapsing-remitting multiple sclerosis and psoriasis. While these drugs appear to be effective, their effects on the gut microbiota and their precise bacterial targets remain unclear. In this study, we investigated how these drugs affect bacteria through a chemical modification called succination, where they react with protein thiol groups (-SH), particularly in cysteine residues. Using proteomics, enzymology and microscopy, we show how this post-translational modification disrupts several key bacterial functions and triggers oxidative and protein stress in E.coli. We also found that fumarate esters can be toxic to various gut bacteria in isolated cultures. Notably, our results demonstrate that when bacteria are studied together in microbial communities, the effect of fumarates can change, either weakening or intensifying. Our findings thus shed light on fumarate esters and microbiota interactions and allow identifying new molecular targets of succination relevant to microbiome health.

microbiology↗

bioRxiv2025

Context-Dependent Metabolic Adaptation in Microbial Communities: From Monocultures to Complex Ecological Interactions

Microbial communities perform myriad functions in various environments, including the mammalian gut. These functions are largely based on the metabolic activity of microbial communities, which arises from the individual members contributions and their interactions. However, microbial functions and interactions are often inferred from simplified systems such as pure or pairwise cultures. Larger communities, in particular, are mainly analysed by metagenomics and the activity is deduced from the genetic potential of their community members. Although these approaches allow detailed insights into compositions, pairwise interactions and potential functions, they neglect the complexities of microbial communities, as evident in higher-order relationships, competition outcomes and the regulatory influence of environmental factors and other community members. Here, we study a mouse gut community along a gradient of complexity - from monocultures, to in vitro communities, to the mouse gut, to probe how bacteria adapt metabolically to their biotic and abiotic environments. Using metaproteomics to analyze realized bacterial niches and metabolic modeling to infer community interactions, we found that bacteria substantially modify their carbon source usage, biosynthetic activities, and protein allocation when grown in communities versus isolation. Furthermore, communities themselves adapted to their growth environment, changing in functionality as well as in the metabolic network between members. Host-associated communities isolated from the mouse gut invested in resource acquisition and utilized a broader spectrum of carbon sources, resulting in a large increase of predicted interactions between them. Our findings demonstrate the remarkable adaptability of microbes and microbial communities across environmental contexts. This underscores the critical need to study microbiomes under near-natural conditions and incorporate context-specific data into functional analyses.

systems biology↗

bioRxiv2022

Nutritional and host environments determine community ecology and keystone species in a synthetic gut bacterial community

Microbe-microbe interactions are critical for gut microbiome function. A challenging task to understand health and disease-related microbiome signatures is to move beyond descriptive community-level profiling towards disentangling microbial interaction networks. Here, we aimed to determine members taking on a keystone role in shaping community ecology of a widely used synthetic bacterial community (OMM12). Using single-species dropout communities and metabolomic profiling, we identified Bacteroides caecimuris I48, Blautia coccoides YL58 and Enterococcus faecalis KB1 as major drivers of in vitro community assembly and elucidated underlying mechanisms of these keystone functions. Importantly, keystone species and bacterial strain relationships were found to strongly vary across different nutritional conditions, depending on the strains potential to modify the corresponding environment. Further, gnotobiotic mice transplanted with communities lacking B. caecimuris I48 and B. coccoides YL58 exhibited morphological anomalies and altered intestinal metabolomic profiles, exposing physiologically relevant functions of these keystone community members. In summary, the presented study experimentally confirms the strong interdependency between bacterial community ecology and the biotic and abiotic environment, underlining the context-dependency and conditionality of bacterial interaction networks.

ecology↗

bioRxiv2021

Bacterial microcompartments for isethionate desulfonation in the taurine-degrading human-gut bacterium Bilophila wadsworthia

BackgroundBilophila wadsworthia, a strictly anaerobic, sulfite-reducing bacterium and common member of the human gut microbiota, has been associated with diseases such as appendicitis and colitis. It is specialized on organosulfonate respiration for energy conservation, i.e., utilization of dietary and host-derived organosulfonates, such as taurine (2-aminoethansulfonate), as sulfite donors for sulfite respiration, producing hydrogen sulfide (H2S), an important intestinal metabolite that may have beneficial as well as detrimental effects on the colonic environment. Its taurine desulfonation pathway involves a glycyl radical enzyme (GRE), isethionate sulfite-lyase (IslAB), which cleaves isethionate (2-hydroxyethane sulfonate) into acetaldehyde and sulfite. ResultsWe demonstrate that taurine metabolism in B. wadsworthia 3.1.6 involves bacterial microcompartments (BMCs). First, we confirmed taurine-inducible production of BMCs by proteomic, transcriptomic and ultra-thin sectioning and electron-microscopical analyses. Then, we isolated BMCs from taurine-grown cells by density-gradient ultracentrifugation and analyzed their composition by proteomics as well as by enzyme assays, which suggested that the GRE IslAB and acetaldehyde dehydrogenase are located inside of the BMCs. Finally, we are discussing the recycling of cofactors in the IslAB-BMCs and a potential shuttling of electrons across the BMC shell by a potential ironsulfur (FeS) cluster-containing shell protein identified by sequence analysis. ConclusionsWe characterized a novel subclass of BMCs and broadened the spectrum of reactions known to take place enclosed in BMCs, which is of biotechnological interest. We also provided more details on the energy metabolism of the opportunistic pathobiont B. wadsworthia and on microbial H2S production in the human gut.

microbiology↗

bioRxiv2021

Exploring the interaction network of a synthetic gut bacterial community

A key challenge in microbiome research is to predict functionality from microbial community composition. As central microbiota functions are determined by bacterial community networks it is important to gain insight into the principles that govern bacteria-bacteria interactions. Here, we focused on growth and metabolic interactions of the Oligo-Mouse-Microbiota (OMM12) synthetic bacterial community, which is increasingly used as model system in gut microbiome research. Using a bottom-up approach, we uncovered the directionality of strain-strain interactions in mono- and pairwise co-culture experiments, as well as in community batch culture. Metabolomics analysis of spent culture supernatant of individual strains in combination with genome-informed pathway reconstruction provided insights into the metabolic potential of the individual community members. Thereby, we could show that the OMM12 interaction network is shaped by both, exploitative and interference competition in vitro. In particular, Enterococcus faecalis KB1 was identified as important driver of community composition by affecting the abundance of several other consortium members. Together, this study gives fundamental insight into key drivers and mechanistic basis of the OMM12 interaction network, which serves as knowledge base for future mechanistic studies.

microbiology↗