Biology subjects

Bund, M.

Publications and source records attributed to Bund, M..

3 recordsLinked to original sources

bioRxiv2026

A multichromatic UV-RGB optogenetic toolbox for control of gene expression in Pseudomonas putida

Optogenetics uses light to provide precise, reversible, and non-invasive control over bacterial functions including gene expression with high spatiotemporal resolution. Although many optogenetic systems have been developed for Escherichia coli, only a limited number is available for other prokaryotes, such as pseudomonads. Here, we establish a toolbox of genomically integrated optogenetic gene cassettes for light-responsive regulation of target gene expression in Pseudomonas putida with UV-A, blue, green, and red light. Using transposon Tn7-mediated chromosomal integration, we implemented four optogenetic systems: the photocaged IPTG/Ptac-LacI system, the LOV-based Dusk switch, the cyanobacteriochrome system CcaS/R, and different bacteriophytochrome-based REDusk variants. Benchmarking with the mCherry reporter demonstrated high dynamic ranges of up to [~]270-fold, low basal expression, and largely homogeneous population responses in P. putida. Spatial illumination further enabled patterned single- and dual-color gene expression. As a proof of concept, we applied the toolbox for light-controlled regulation of pyoverdine (PVD) biosynthesis in P. putida. The expression of the alternative sigma factor PfrI, which upregulates the production of the siderophore during iron-limitation, was placed under optogenetic control in a {Delta}pfrI background. The red-light responsive switches resulted in the strongest induction of PVD synthesis and enabled spatial control of siderophore-mediated microbial interactions. To demonstrate transferability, light-dependent pyoverdine production was further established in the human pathogen Pseudomonas aeruginosa PAO1. Together, this optogenetic plug-and-play toolbox enables non-invasive, spatiotemporal reprogramming of gene expression and cellular processes in pseudomonads and expands the available optogenetic repertoire beyond established model organisms.

synthetic biology↗

bioRxiv2026

Context-dependent siderophore exploitability shapes microbial community structure

1)Siderophores are classically viewed as shared iron-scavenging public goods, yet their ecological roles in multispecies communities remain poorly defined. Here, we establish a synthetic microbial community to dissect how different siderophores, their uptake compatibility and spatial structure shape iron competition. Using Corynebacterium glutamicum as a model, we show that this siderophore non-producer accesses diverse xenosiderophores, including enterobactin secreted by Escherichia coli. However, exploitation was constrained and co-cultures converged to stable compositions. Dose-response experiments combined with mathematical modelling indicated that the producer retains more effective access to enterobactin than the exploiter. Presence of Pseudomonas putida altered this interaction, as it exploited enterobactin while producing pyoverdine, a siderophore inaccessible to the other community members that restricted their iron access. Across different cultivation scales, community dynamics was strongly influenced by spatial organization and initial composition. These findings identify siderophores as context-dependent iron-allocation agents that can promote microbial coexistence or exclusion.

microbiology↗

bioRxiv2026

DNA-intercalating antiphage molecules trigger abortive infection through mutual destruction and synergize with bacterial immunity

Bacteria deploy diverse antiphage defense systems, including small bioactive molecules providing protection at the multicellular level. DNA-intercalating anthracyclines, such as daunorubicin, exhibit broad antiphage activity, but the underlying mechanism has remained elusive. Here, we systematically screened the Escherichia coli BASEL phage collection to elucidate the mode of action of DNA-intercalating antiphage molecules. We identified taxonomically distinct clusters of susceptible viral groups and show that, in T5-like phages (Markadamsvirinae), daunorubicin blocks infection after first-step transfer (FST). In the presence of daunorubicin, continued expression of pre-early genes leads to abortive infection via mutual destruction, where both phage and host succumb. Analogous abortive-infection phenotypes occur across taxonomically diverse phages exposed to chemically distinct DNA-intercalating molecules. Notably, we show that daunorubicin synergizes with downstream nucleic acid-targeting defenses underscoring context-dependent outcomes. Together, these findings reveal how chemical defense contributes to the multilayered antiviral immunity and highlight the intricate interplay between mechanistic inhibition and infection outcome.

microbiology↗