Biology subjects

Remus-Emsermann, M.

Publications and source records attributed to Remus-Emsermann, M..

4 recordsLinked to original sources

bioRxiv2026

Developing permeable polydimethylsiloxane-based biomimetic leaf surfaces to study phyllosphere microbial ecology.

Polydimethylsiloxane (PDMS) is an excellent material for the construction of biomimetic leaf replicas which reproduce leaf surfaces with high fidelity. This allows for the study of leaf surface-colonizing bacteria and the impact of the leaf topology on bacterial distributions and behavior. However, their application is limited to short-term experiments, as long term survival of microorganisms on their surface is not possible due to a lack of nutrient replenishment. On living leaves, nutrients diffuse across the cuticle via leaching, a process not yet replicated in biomimetic systems. Here, we explore whether water and fructose can be supplied to microbial colonizers on PDMS membranes by mimicking leaching. We created hybrid membranes by incorporating polymers (Carbopol, Pemulen, cellulose microfibers, cellulose nanocrystals, and polyvinylpyrrolidone) to enhance nutrient transport. We determined that bulk diffusion of water correlated negatively with membrane thickness and positively with polymer concentration. Further, fructose diffusion across hybrid membranes reached similar rates compared to isolated Populus x canescens leaf cuticles. Under high relative humidity, these membranes supported long-term bacterial survival. Our findings represent important steps towards the development of topomimetic leaf surfaces that sustain microbial life, enabling further investigation into the microbe-microbe interactions that take place on leaves.

microbiology↗

bioRxiv2024

Spatial structure affects the establishment and persistence of closed microbial ecosystems

Why Earth has remained habitable for billions of years is a question that has long fostered debate in biology and earth sciences. Closed systems approaches have yielded information about the underlying mechanisms, including the persistence of matter recycling. However, the majority of these studies have been conducted under relatively homogenous conditions using aquatic systems. Here, we investigated the effect of spatial structure and heterogeneity on the persistence or failure of closed microbial biospheres. This mimics unsaturated soil-like conditions that were inoculated with a two species producer-decomposer community. Specifically, we investigated how microhabitat physical structure and necromass spatial distribution affected population dynamics and system time-to-failure. We observed strong effects of microhabitat structure, including particle size and moisture level, on persistence at both the population and system levels. Systems containing the smallest substrate particles failed quickly and on average did not support decomposer populations except at high initial cell densities. Persistence was promoted by larger substrate particles, likely due to larger pore sizes resulting in shorter movement distances and better accessibility to resource patches (i.e. necromass). Building on these findings, we manipulated necromass patch distribution and observed that algae clustered around necromass patches when present. Necromass patch distribution had small but significant effects on persistence, with lower persistence in intermediate vs. high or low necromass heterogeneity. Together these findings indicate a limit to the spatial/physical parameter space in which producer-decomposer communities can establish and self-sustain via self-recycling of necromass.

ecology↗

bioRxiv2019

Replicating Arabidopsis Model Leaf Surfaces for Phyllosphere Microbiology

Artificial surfaces are commonly used in place of leaves in phyllosphere microbiology to study microbial behaviour on plant leaf surfaces. Studies looking into individual environmental factors influencing microorganisms are routinely carried out using artificial surfaces. Commonly used artificial surfaces include nutrient agar, isolated leaf cuticles, and reconstituted leaf waxes. However, interest is growing in using microstructured surfaces mimicking the complex topography of leaf surfaces for phyllosphere microbiology. As such replica leaf surfaces, produced by microfabrication, are appearing in literature. Replica leaf surfaces have been produced in agar, epoxy, polystyrene, and polydimethylsiloxane (PDMS). However, these protocols are not suitable for replicating fragile leaves such as of the model plant Arabidopsis thaliana. This is of importance as A. thaliana is a model system for molecular plant genetics, molecular plant biology, and microbial ecology. Here we present a versatile replication protocol for replicating fragile leaf surfaces into PDMS. We display the capacity of our replication process using optical microscopy, atomic force microscopy (AFM), and contact angle measurements to compare living and PDMS replica A. thaliana leaf surfaces. To highlight the use of our replica leaf surfaces for phyllosphere microbiology, we visualised bacteria on the replica leaf surfaces in comparison to living leaf surfaces.

microbiology↗

bioRxiv2018

Chromatic Bacteria - A broad host-range plasmid and chromosomal insertion toolbox for fluorescent protein expression in bacteria

Differential fluorescent labelling of bacteria has become instrumental for many aspects of microbiological research, such as the study of biofilm formation, bacterial individuality, evolution, and bacterial behaviour in complex environments. We designed a variety of plasmids, each bearing one of eight unique, constitutively expressed fluorescent protein genes in conjunction with one of four different antibiotic resistance combinations. The fluorophores mTagBFP2, mTurquoise2, sGFP2, mClover3, sYFP2, mOrange2, mScarlet-I, and mCardinal, encoding for blue, cyan, green, green-yellow, yellow, orange, red, and far-red fluorescent proteins, respectively, were combined with selectable markers conferring tetracycline, gentamicin, kanamycin, and/or chloramphenicol resistance. These constructs were cloned into three different plasmid backbones: a broad host-range plasmid, a Tn5 transposon delivery plasmid, and a Tn7 transposon delivery plasmid. The utility of the plasmids and transposons was tested in bacteria from the phyla Actinobacteria, Proteobacteria, and Bacteroidetes. We were able to tag representatives from the phylum Proteobacteria at least via our Tn5 transposon delivery system. The here constructed plasmids are available to the community and provide a valuable tool to investigate bacteria-bacteria, bacteria-host, and bacteria-environmental interactions.

microbiology↗