Biology subjects

Lamprecht, O.

Publications and source records attributed to Lamprecht, O..

3 recordsLinked to original sources

bioRxiv2025

Effects of multiple cell regulators on curli gene expression in Escherichia coli

Curli amyloid fibers is the key protenacious component of extracellular matrix in Escherichia coli. Regulation of curli expression is highly complex and depends on the cellular response to diverse environmental conditions. Although many genetic determinants of curli production are known, previous studies were performed under diverse conditions and using different strains of E. coli or Salmonella. Furthermore, the origin of bimodal curli expression in bacterial population remains unknown. Here, we systematically investigated the role of multiple cell factors in expression of curli structural genes csgBA in unstructured planktonic E. coli culture. We observed that multiple regulators involved in regulation of stress response, cell motility, cell physiology and metabolism, as well as in formation of extracellular matrix and maintenance of DNA architecture modulated expression of curli by either promoting or repressing activity of csgBA. We further elucidated which regulators act upstream of the master transcription factor CsgD and which are crucial for bimodality of curli gene expression. We also investigated the impact of individual diguanylate cyclases on the regulation of the csgBA activity. This study provides an overview of regulation of curli gene expression in planktonic E. coli culture in the absence of any microenvironmental gradients.

microbiology↗

bioRxiv2022

Dynamic bimodality of curli expression in planktonic cultures of Escherichia coli is stabilized by cyclic-di-GMP regulation

Curli amyloid fibers are a major constituent of the extracellular biofilm matrix formed by bacteria of the Enterobacteriaceae family. Within Escherichia coli biofilms, curli gene expression is limited to a subpopulation of bacteria, leading to heterogeneity of extracellular matrix synthesis. Here we show that bimodal activation of curli expression occurs not only in submerged and macrocolony biofilms, but also in well-mixed planktonic cultures of E. coli, resulting in all-or-none stochastic differentiation into distinct subpopulations of curli-positive and curli-negative cells at the entry into the stationary phase of growth. Stochastic curli activation in individual E. coli cells could further be observed during continuous growth in a conditioned medium in a microfluidic device, which further revealed that the curli-positive state is only metastable. In agreement with previous reports, regulation of curli gene expression by c-di-GMP via two pairs of diguanylate cyclase and phosphodiesterase enzymes, DgcE/PdeH and DgcM/PdeR, modulates the fraction of curli-positive cells under all tested growth conditions. Unexpectedly, removal of this regulatory network does not abolish the bimodality of curli gene expression, although it affects dynamics of activation and increases heterogeneity of expression levels among individual cells. Moreover, the fraction of curli-positive cells within an E. coli population shows stronger dependence on growth conditions in the absence of c-di-GMP regulation. We thus conclude that, while not required for the emergence of bimodal curli gene expression in E. coli, this c-di-GMP regulatory network attenuates the frequency and dynamics of gene activation and increases its robustness to cellular heterogeneity and environmental variation.

microbiology↗

bioRxiv2021

Synthetic periphyton as a model community to examine species dynamics in complex microbial consortia

Phototrophic biofilms, also known as periphyton, are microbial freshwater communities that drive crucial ecological processes in streams and lakes. Gaining a deep mechanistic understanding of the biological processes occurring in natural periphyton remains challenging due to the high complexity and variability of such communities. To address this challenge, we rationally developed a workflow to construct a synthetic community by co-culturing 26 phototrophic species (i.e., diatoms, green algae and cyanobacteria) that were inoculated in a successional sequence to create a periphytic biofilm on glass slides. We show that this community is diverse, stable and highly reproducible in terms of microbial composition, function and 3D spatial structure of the biofilm. We also demonstrate the ability to monitor microbial dynamics at the single species level during periphyton development and how their abundances are impacted by stressors such as increased temperature and a herbicide, singly and in combination. Overall, such a synthetic periphyton, grown under controlled conditions, can be used as a model system for theory testing through targeted manipulation.

synthetic biology↗