Annual Conference 2025 of the Association for General and Applied Microbiology - Jahrestagung 2025 der Vereinigung für Allgemeine und Angewandte Mikrobiologie

Prof.

Prof. Dr.

Tracing active members in microbial communities by BONCAT and click chemistry-based enrichment of newly synthesized proteins

Microbial communities

Motivation and aimsUnderstanding microbial community (MC) dynamics is key to advancing environmental microbiology, human health, and biotechnology. Metaproteomics analyzes all proteins in an MC, providing taxonomic and functional insights. Microbial activity and adaptation involve the synthesis of new proteins (nP), but differentiating nP from bulk proteins is challenging. Applying bioorthogonal non-canonical amino acid tagging (BONCAT) with click chemistry has demonstrated efficacy in enriching nP in pure cultures. However, transferring this technique to MC has been proven challenging due to inefficient BONCAT processes, resulting in low nP yield and high contamination from non-labeled bulk proteins. To address this issue, a new workflow to enrich nP from complex MC was developed. Initially tested with E. coli (labeled) and yeast (unlabeled control), the workflow was applied to an anaerobic MC from a laboratory biogas reactor.MethodsAfter shifting from glucose to lactose, E. coli proteins were labeled with 4-Azido-L-homoalanine (AHA) and mixed with unlabeled yeast. AHA-labeled proteins were biotinylated via click chemistry, enriched using magnetic streptavidin beads, digested, and analyzed using LC-MS/MS. Protein identification was performed with MASCOT and MetaProteomAnalyzer. The workflow was then applied to an anaerobic MC shifted from glucose to ethanol, labeling the nP with AHA.Results and discussionUsing breakable biotin linkers, amino acid bead blocking, and optimized washing resulted in specific enrichment of nP from E. coli (555 E. coli, 21 yeast in enriched sample versus 885 E. coli, 590 yeast in non-enriched sample). In the unlabeled control, only 7 proteins were detected. Applying the optimized workflow to the anaerobic MC identified 441 metaproteins, compared to 12 in the non-labeled control. Identifying a bifunctional alcohol dehydrogenase and syntrophic interactions between an ethanol-utilizing bacterium and two methanogens (hydrogenotrophic and acetoclastic) demonstrates the potential of metaproteomics targeting nP to trace microbial activity in complex MC.

Poster

Mag.med.vet.

Dr.rer.nat.

Assoz.Prof. Mag.med.vet.

RNA-Based characterization of metabolically active microbial communities during beef slaughtering

Microbiological contamination on beef carcasses not only shortens shelf-life but also poses significant risks to food safety. RNA-based analysis offers an accurate detection of metabolically active microbes. In this study, we investigated the metabolically active portion of the microbiota at key processing stages (skinning, splitting, chilling) in an Austrian slaughterhouse. A total of nine surface samples were collected from the carcasses during the skinning and chilling stages, while ten samples were collected during the splitting stage, all preserved using RNAlater. Total RNA was extracted, converted to cDNA, and subjected to 16S rRNA gene sequencing (Illumina MiSeq). Analyses were performed with QIIME 2, R and DESeq2. While alpha diversity did not change significantly during slaughter, PERMANOVA analysis identified the processing step as a significant factor influencing sample variance. The genera Pseudomonas, Serratia and Escherichia-Shigella were highly abundant during the skinning and chilling stages but showed comparatively lower abundance during carcass splitting. Among the Firmicutes, Staphylococcus was more prevalent during skinning while Mycoplasma exhibited higher abundance during both the splitting and chilling stages. The relative abundance of Corynebacterium was higher during both the skinning and splitting stages, while Bifidobacterium was more prevalent during skinning compared to the other stages. Notably, there were substantial differences in ASVs representing Gulbenkiania and Exiguobacterium between the skinning and carcass splitting stages, as well as between skinning and the chilling stages. In contrast, a higher expression of ASVs associated with Halomonas and Bacillus was observed at the chilling station compared to the skinning station. The high activity of Pseudomonas, a known psychrotrophic spoilage organism, during skinning and chilling highlights its role in cold storage spoilage, while Serratia and Escherichia-Shigella are indicators of faecal contamination and hygiene lapses. The increased abundance of active Mycoplasma suggests its resilience in low-nutrient and stressed environments, potentially contributing to biofilm formation. Variations in ASVs for Gulbenkiania and Halomonas suggest their involvement in oxidative stress response and biofilm development, which could influence meat quality and contribute to microbial persistence during the chilling process.

Prof.  Dr.

Engineering cyanobacteria as the basis for a synthetic microbial community

In nature, different microorganisms form highly complex communities in which every species has a distinct role. To increase our understanding of the complex structures and interactions within microbial communities and the role of each microbial partner, the design and analysis of simplified microbial model communities is necessary.In this collaborative project, our goal is the de novo design of a synthetic microbial cross-kingdom community based on the well characterized and genetically amenable model organisms representing cyanobacteria (Synechocystis sp. PCC 6803, or Synechococcus elongatus PCC 7942), ascomycete (Saccharomyces cerevisiae) and basidiomycete fungi (Ustilago maydis).Co-cultivation is based on the carbon source sucrose, which is produced by the phototrophic cyanobacterium using light and carbon dioxide. Sucrose secretion into the culture medium is achieved by inducible, heterologous expression of a sucrose permease gene in the cyanobacteria. This approach is often combined with salt stress or metabolic pathway engineering to increase sucrose production and secretion.An important aspect for creating a synthetic community is to design and establish tools for the formation of stable co-cultures and the analysis/quantification of the microbial partners of the community. Thus, in this part of the project, we test different cultivation devices and photobioreactor setups for online monitoring of co-cultures as well as single-cell flow cytometry analysis for quantification of individual populations within the co-culture. Another important aspect for the formation of a synthetic microbial community is the characterization of the optimal cultivation conditions for cyanobacterial sucrose production and simultaneous growth of all co-culture partners. In order to track the carbon source sucrose and other important metabolites within the co-culture, we also intend to establish biosensors in cyanobacteria.Exploiting these established tools, we will create a stable synthetic microbial community which will then be further used to characterize the nutrient exchange in microbial consortia with a special focus on carbon economics and logistics.Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB1535 - Project ID 458090666.Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Major Research Instrumentation INST 208/808-1.

Exploring microbial dynamics of Polymicrobial biofilms on Bilioenteric catheters

During liver transplantations gut microbiota may infiltrate the biliary system. This can lead to postoperative polymicrobial infections and thus cholangitis, suspected to result from bacterial colonization of bilioenteric catheters as well as by immunosuppressive treatment. Cholangitis can lead to systemic, life-threatening infections such as sepsis or organ failure. Therefore, understanding the dynamics of polymicrobial biofilms on bilioenteric catheter is of high importance.The most prevalent families of microorganisms found in biofilms on biliary catheters are gram-positive Enterococcaceae and gram-negative Enterobacteriaceae. Enterococcaceae are less abundant than Enterobacteriaceae in the biofilms but have an equivalent tendency to be isolated from cholangitis patients – suggesting that potentially pathogenic Enterococcaceae may be sustained within mixed bilioenteric catheter biofilms by interactions with Enterobacteriaceae. This study therefore aimed to elucidate the inter- and intraspecies communication between representative isolates of Enterococcaceae and Enterobacteriaceae isolated from bilioenteric catheters, in a standardized in vitro system. We investigate spatial and temporal changes in biofilm structure and composition using microscopy and viability staining, colony forming units (CFU) counting and 16S rRNA gene sequencing for microbiome analysis. We determined how the microbial dynamics of polymicrobial interaction changed between Enterococcaceae and Enterobacteriaceae comparing planktonic to biofilm growth on various catheter materials. Additionally, we investigated the influence of intrinsic factors such as antibiotic resistance genes or external factors such as bile acids and antibiotics on these dynamics. Furthermore, we use bioinformatical tools to explore the microbial dynamics of polymicrobial interaction Enterobacteriaceae and Enterococcaceae at a genetic level in clinical samples and reconstituted lab microbiomes.This multifaceted approach aims to provide insight into the mechanisms of polymicrobial biofilm formation in the biliary system and identify potential interventions to mitigate postoperative complications in patients.

Establishment of a conditional knockout system in the endosymbiont-harboring trypanosomatid Angomonas deanei

Introduction: Mitochondria and plastids originate from endosymbiotic events more than one billion years ago in which free-living bacteria were taken up by a host cell and subsequently evolved into organelles that are now fully integrated into the cellular networks of the host. Since the acquisition and evolution of these organelles date far back in time, we use the trypanosomatid Angomonas deanei, which acquired a bacterial endosymbiont (ES) more recently, to study early steps of endosymbiosis. A. deanei harbors a single β-proteobacterial ES whose cell cycle is synchronized with and likely controlled by the host by so-called endosymbiont-targeted proteins (ETPs) that are encoded by the host but transported to the ES.Goal: Preliminary work revealed that homozygous deletions of several ETP-encoding genes cannot be obtained, suggesting that these genes are essential for survival of the symbiosis. Thus, to study how the ETPs effect the host-ES interaction, we aimed to develop genetic tools to generate inducible homozygous knockout (or knockdown) mutants.Methods & results: To this end, we generated an A. deanei strain that produces the T7 RNA polymerase (T7RNAP) from a highly expressed locus. To avoid interference with the endogenous expression machinery we identified at least seven potentially silent loci that appeared suitable for transgene insertion and were expected to be transcriptionally inactive under native conditions. Using a blasticidin resistance cassette with T7 promoter as a reporter gene in the T7RNAP background, we demonstrated T7RNAP-dependent gene expression from one of these silent loci. Finally, implementation of the transcriptional regulator TetR enabled us to induce expression in a ligand-depended manner. Furthermore, we are exploring the integration of a blue light-inducible T7RNAP in A. deanei.Summary: A. deanei is an emerging model system to study early steps of organellogenesis. The conditional knockout system, that enables now inducible perturbations of the system, will be key for the in-depth exploration of the host-ES interaction, and, in particular, to observe effects of ETP losses.

Does the vitamin B2 analogue roseoflavin have the potential to influence the composition of the oral microbiome?

Streptococcus mutans is auxotrophic for riboflavin (RF, vitamin B2) and thus depends on its uptake from the environment [1]. In its natural soil habitat, Streptomyces davaonensis produces the antivitamin roseoflavin (RoF), an antimicrobial RF analogue, to reduce growth of competing microorganisms [2]. We hypothesized that RoF might be useful as a microbiome modulator against potential oral pathogens, e.g. involved in caries formation. However, little is known about the antimicrobial efficacy of RoF against members of the human oral microbiota.In the cultivation-based arm of our study, more than 300 microbial isolates were obtained from saliva samples of 41 healthy human volunteers and characterized by MALDI-TOF-MS. Securely identified species were analysed with regard to the presence of RF biosynthesis and uptake genes and tested for susceptibility to RoF in RF-free media supplemented with RF and/or RoF, respectively. For cultivation-independent studies, we obtained saliva samples from 15 healthy volunteers, which were pooled and incubated with or without RoF for 24 hours, respectively. After DNA and RNA extraction, 16S rRNA (cDNA) and 16S rRNA gene sequencing was used to investigate shifts in the community composition of the present (DNA-based) or active (cDNA-based) saliva microbiota.None of the isolated gram-negative species were found to be RF auxotrophic, while 7 out of 19 gram-positive species grew significantly better when supplemented with RF (100 µM). Similarly, growth of 11 out of 12 tested gram-negative species was not negatively affected by RoF (100 µM), whereas 11 out of 19 gram-positives showed growth reduction, including S. mutans. Our data tentatively suggested that RoF-treatment shifts the human oral microbiota towards the gram-negative fraction [3]. However, our 16S-sequencing-based incubation experiment did not confirm a relative increase of the gram-negative fraction, neither on DNA- nor on RNA-basis. We believe that under the growth conditions used, too few cell divisions took place to reduce the cell number of the riboflavin-auxotrophic species. Consequently, future experiments will address monitoring of RF-concentrations and different bacterial growth conditions.[1] Turner et al. (2020), J Bacteriol 203(2): e00293-20; [2] Pedrolli et al. (2014), Methods Mol Biol 1146: 41-63; [3] Schwendenmann et al. (2024). Folia Microbiol, submitted.

Tripartite interaction between wood-decay Basidiomycetes andhabitat sharing microbes

Wood-decay basidiomycetes, such as the ubiquitous white-rot fungus Schizophyl- lum commune, fulfill an important ecological role by contributing to global carbon cycling through the degradation of lignocellulose and woody material. However, the brown-rot fungus Serpula lacrymans also represents an economic burden, by in- vading buildings and destroying wood construction material. Natural environments of both fungi are characterized by the interaction with habitat sharing microor- ganisms. Besides competition with other fungal decomposers, both fungi interact with bacteria. Such bacterial-fungal interactions can be classified as mutualistic or antagonistic, with levels in between, and often involve the production of natural products. While Bacillus subtilis attaches to the hyphae of S. commune (fungal highway), it induces the production of natural products including terpenoids in S. lacrymans. The aim of our study is to understand how consortia stimuli are recognized and transduced inside basidiomycete cells. Special attention is given to elucidate the production of terpenoids in S. commune and how they mediate microbial inter- actions. We use knockout and overexpression of genes in signaling cascades of S. commune to identify pathways involved in the interaction between both fungi. Growth and combative ability are evaluated on defined media with different carbon sources associated with wood and stressors of signaling pathways. Changes in gene expression due to bacterial cues are anaylzed by RT-qPCR. Furthermore, we characterize the inter- and intra-kingdom interactions by micromorphology and flu- orescence microscopy. Putative terpene synthases of S. commune are characterized by heterologous expression. Overall, our results help to elucidate the dynamic interactions between fungi and bacteria and highlight the importance of terpenoids as predominant natural product of basidiomycetes.

Modelling tripartite microbial population dynamics

Microorganisms are omnipresent in nature, where they form diverse communities consisting of genetically different strains or even a variety of species that interact and co-exist. Mathematical models can be used to systematically unravel the intricacies of coexistence and competition dynamics among the members of microbial colonies over time. This study extensively explores the metabolic interactions occurring over time within the heterotrophic members of microbial communities by emphasizing the co-cultivation of photoautotrophic and heterotrophic partners within the community structure. The main objective is to employ a population dynamics model along with an evolutionary game theoretical framework to investigate how three distinct metabolic strategies—Public metabolizer, Private metabolizer, and Cheater (also referred to as defector or free rider) affect the dynamics, composition, and stability of a consortium. Our suggested population model is based on the Nonlinear Lotka-Volterra framework, where the growth of other strains is influenced by the glucose extracted by the Public metabolizer and the available sucrose. This analytical approach enables us to understand the stability and instability conditions of cooperation and competition which indicate the general rules for the survival and extinction of the members of our designed synthetic cross-kingdom community linked vai nutrient exchange. This work provides valuable insights into the ecological dynamics of microbial systems and offers a foundation for further investigations into the impact of cheater and privatizer on stability and resilience. The anticipated outcomes may influence various domains, including environmental management, ecosystem engineering, and applications in biotechnology, by shaping creative approaches based on the study's discoveries.

Prof. , Dr.

Effect of soil and microorganisms in truffle growth

Truffles are hypogeous ascomycetous fungi belonging to Tuber genus, which form ectomycorrhizal association with oak, hazel and beech. The expensive edible mushrooms are known for its unique flavour and smell. The role of microbial communities associated with truffles are rather unknown. The aim of the project is to understand the effect of soil and microorganisms on cultivation of Tuber on truffle field sites.There were two different type of sampling sites in Thüringia- two test field sites and a natural site. Both the test field sites were treated with truffle growth supplements- Truf up and Rhizovital. Soil community analyses and element analyses of test field and natural sites were done along with isolation of microorganisms from soil nearby of fruiting bodies and the gleba of fruiting bodies of the natural site. Interaction studies of T. borchii with isolated bacteria was carried out in Petri dishes under different conditions. Based on the results of interaction with T. borchii, a consortia was prepared and applied it on the test field sites.Soil community analysis of natural site revealed dominance of Proteobacteria, Actinomycetia, Mortierellomycetes, Sordariomycetes and Dothideomycetes. Whereas in test field sites, lower diversity was found. After three years, the microbial community had a significant rise of Tremellomycetes and a drop of Mortierellomycetes in the treatment plots.A strain collection with 355 microorganisms contained predominantly of Streptomyces sp., Pseudomonas sp. and Bacillus sp were created from the soil and fruiting bodies of natural sites. First analyses of bacterial interaction with truffles showed that species of Proteobacteria and Actinobacteria induced faster growth of truffle mycelium with visible mycelium after 4 days interaction. Moreover, the absence of light showed a positive growth of truffle mycelium, when compared with light conditions.Over the span of three years, a change in the microbial communities in the test field sites were observed which were similar with natural sites of truffles. Along with that, the interaction of truffle helper bacteria with truffles were effective, which were then used as consortia for the test field sites.

A versatile microfluidic platform for the cultivation of cyanobacteria at single-cell resolution

IntroductionThe primary endosymbiosis theory states, that about one billion years ago a heterotrophic host organism incorporated a cyanobacterium, which subsequently evolved into the chloroplast we find in algae and plants today. However, the early steps in the establishment of endosymbiosis and the transition towards an organelle have not been experimentally tested yet. Furthermore, cyanobacteria are expected to play a key role a future bio-economy. GoalsEstablish microfluidic single-cell cultivation for high-throughput characterization of cyanobacteria. The technology will later be used to trap and observe single cells in picoliters of medium, mimicking the inclusion vacuole during early endosymbiosis. Materials & MethodsCyanobacteria are cultivated in a strict monolayer, therefore self-shading of cells is avoided. The use of the highly gas-permeable polydimethylsiloxane (PDMS) to fabricate cultivation chips allows cultivation without carbon limitation.A method was developed to generate a linear light-intensity gradient along the microfluidic chip, allowing growth data to be generated at high-throughput. Cells were segmented using a deep learning based algorithm. Python scripts were used for cell segmentation and subsequent data analysis.Dynamic CO2 control was enabled by stacking an additional PDMS layer on top of the thin film cultivation chip. CO2-depleted air was then perfused through the gas layer in countercurrent to the medium flow. ResultsThe cyanobacterial strains Synechococcus elongatus UTEX2973 and PCC7942 as well as Synechocystis sp. PCC6803 were used as model organisms. Using the image analysis pipeline, TB of image data containing millions of cells were analysed. It was shown that UTEX2973 grows without carbon limitation in the microfluidic cultivation system when operating it at ambient air. Using dynamic CO2 control, it was shown that carbon limitation first occurs at a CO2 concentration of 15 ppm. In comparison to UTEX2973, PCC7942 showed higher CO2-dependent growth rates. PCC6803 was the slowest cyanobacterial strain tested. No divergence of growth rates in the direction orthogonal to the light intensity-gradient was observed. SummaryA versatile platform for the characterization of cyanobacteria at single cell resolution was developed and published1. In the near future, the platform will be used to test hypotheses related to endosymbiosis.1: Witting et al., Lab Chip, p., 2024, doi: 10.1039/D4LC00567H.

From cyanobacteria to cell organelle – Engineering and studying minimal endosymbiotic metabolism

In eukaryotes, photosynthesis evolved through endosymbiotic incorporation of a photosynthetic cyanobacterium, which became the ancestor of plastids. The transformation entailed gene transfer from the endosymbiont to the host nucleus, evolution of protein targeting systems, as well as synchronization of host and endosymbiont cell cycles. The ménage-à-trois (MAT) hypothesis proposes that the linkage of carbon and energy metabolism, established by the integration of transporters gained by horizontal gene transfer from Chlamydia-like endoparasites, was the primary driver of the endosymbiosis (Karkar et al., 2015).In order to investigate whether the linkage of host and endosymbiont carbon and energy metabolism could be sufficient for the establishment of endosymbiosis, we aim to enforce a synthetic endosymbiont-like metabolism in the model cyanobacterium Synechocystis sp. PCC 6803. By deletion of the glgC gene, the precursor for the energy storage compound glycogen will no longer be produced. Implementation of the Chlamydia-like transporter UhpC will alleviate carbon overflow reactions (Gründel et al., 2012) via export of excess carbon out of the cell during periods of light. Implementation of the transporter NTT will allow uptake of external ATP for energy during periods of darkness. Markerless deletion will be used to sequentially erode the genome, while diurnal growth, transcriptomes and metabolomes will be characterized. Our microfluidic platform (Witting et al., 2024) will be used to mimic the host cytoplasm during early stages of endosymbiosis, enabling analysis of cyanobacterial physiology in response to metabolomic rerouting and special constraints at single cell resolution. Additionally, the introduction of metabolite sensors will enable real-time readouts of metabolic changes within the cell.The successful knockout of glgC has been achieved and three independent Synechocystis ∆glgC knockout lines have been characterized under diurnal growth conditions. The transcriptomes and metabolomes of the mutant lines reveal stressed phenotypes and increased energy charge as well as metabolic re-routing. Strains expressing Chlamydia-like transporters are tested for their efficiency to complement the metabolic overflow in light and energy shortage in darkness.

The microbiome of a paper mill

IntroductionPaper production consumes large amounts of water and energy. This can be reduced by using a closed water cycle and producing primary energy by anaerobic water treatment. This water treatment cycle consists of UASB reactors for anaerobic water treatment, a subsequent stripping of carbon dioxide and waste gases, a lime trap and the final treatment of waste air using a trickle bed reactor and a biofilter. Continuous operation revealed the formation of biofilms and odor as some challenges related to the microbial communities established in the systems. GoalsThe study aims at a better understanding of microbial functions and to identify key targets for process optimization. Materials & MethodsCombined metagenomics and metaprotomics were applied to analyze the microbial communities. Extracted microbial proteins from water cycle were tryptically digested, transferred to nanoHPLC-MS/MS (TimsTOF Pro) and identified by search against a protein sequence database based on corresponding metagenome data. ResultsThe combined metagenomics and metaproteomics approach showed a complex microbial community which clearly differs between the process stages: (i) samples from paper production and contaminated water showed higher abundance of Bacillalles and Lactobacillales, (ii) anaerobic treatment in UASB reactors contained more Methanomicrobiales, Enterobacterales and Thiotrichales, (iii) aerobic treatment and cleaned water and finally (iv) exhausted air treatment showed higher abundance of Burkholderiales. These differences correlated well with the different process conditions.Functional analysis showed hydrogenotrophic methanogenesis in the UASB reactors and acidogenesis from organics as well as methanogenesis from methylated amines in the contaminated water from paper production. Detecting methanogenesis from methylated amines was surprising but correlated with anaerobic conditions in these samples. The detection of methanogenic functions in the final aerobic cleaned water could be explained by a partial loss of methanogenic biomass from the UASB reactor. SummaryThe metaproteome analysis of microbial communities from closed water cycle of a paper mill provided insight into community structure and functions. Data can be used to further optimize the system.

Insights into establishment and maintenance of lichen communities through structural bioinformatics and synthetic microbial consortia

Lichens are remarkable examples of complex microbial cross-kingdom communities, thriving in some of the harshest environments on Earth. These symbioses, comprising fungi (mycobionts) and photosynthetic partners like algae or cyanobacteria (photobionts) but also additional bacterial members, have been traditionally difficult to study due to their complexity. A detailed molecular understanding of interactions between the community members is still missing.The main focus of our research is therefore to elucidate the mechanisms that control the formation, stabilization, and maintenance of lichens. From other fungal interactions, it is already known that secreted proteins play a vital role in recognition, facilitation of cell-cell contact, regulation of growth, and production of metabolites. Known as effector proteins, these molecules have key roles in both symbiotic but also pathogenic interactions.For this reason, we are focusing on the identification and classification of secreted proteins through bioinformatic mining of sequenced genomes of Peltigera lichens. By leveraging structural prediction and clustering algorithms, our bioinformatic pipeline is able to identify effector proteins that traditional sequence-based methods often miss. This approach already allowed us to identify structurally conserved proteins also found in pathogenic fungi but revealed a large number of currently uncharacterized protein families. However, a detailed functional understanding of these proteins is currently lacking.As lichens are not efficiently amenable to genetic manipulation, we will use synthetic communities composed of well-characterized model microbes. These communities comprise Synechocystis, Saccharomyces cerevisiae, and the dimorphic fungus Ustilago maydis, and allow us to investigate the effects of candidate effector proteins. As the members in a lichen community are spatially closely associated, we plan to incorporate surface-presented proteins that allow us to connect the individual organisms in a controllable manner. To this end, we develop a U. maydis-based surface display system, making use of the carbohydrate-binding properties of lectins – a class of secreted proteins that have been shown to facilitate cell-to-cell contacts and are also present in lichens.By unraveling the molecular secrets of lichen effector proteins, we hope to shed light on the fundamental principles of microbial cooperation using these ancient symbionts as exemplars.

Siderophore typing, a powerful tool to study their role in mediating microbial networks

Siderophores are iron chelating molecules that are produced by a variety of microorganisms and have essential functions in building microbial communities. An important group of siderophores are the pyoverdines, a structurally diverse group of chromopeptides with species-specific differences in the peptide sequence and side group structure. Here we describe the development of an LC-MS/MS-based approach to investigate the role of pyoverdines in the interaction of microbial communities. This method utilizes the characteristic fragmentation pattern of all pyoverdines that occurs in the all-ion fragmentation mode and takes advantage of the fact that all pyoverdines are ionized as M2+ ions. In this way, we are able to explore the diversity of pyoverdines and their possible modification.

Microbial communities 1

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