Biology subjects

Jespersen, M. G.

Publications and source records attributed to Jespersen, M. G..

5 recordsLinked to original sources

bioRxiv2026

Automated mini-bioreactors reveal the temporal dynamics and multi-omics responses of CRISPRi knockdowns in Pseudomonas putida

Characterizing CRISPR interference (CRISPRi) phenotypes presents a fundamental temporal challenge: pre-existing overabundance of target proteins can mask early silencing, requiring extended growth for dilution, yet prolonged repression rapidly selects for escaper mutants. To resolve this, we integrated a tightly regulated CRISPRi system in Pseudomonas putida with an automated mini bioreactor platform operating in turbidostat mode. By maintaining continuous exponential growth, we mapped the exact temporal dynamics of essential gene silencing. We identified a critical observation window between 17 and 27 hours (7-9.5 cell doublings) where repression exerts its maximum physiological impact, directly preceding population takeover by target-site mutated escapers. Applying this workflow to the arginine biosynthesis pathway, multi-omics profiling disentangled transient physiological buffering from long-term mutational events, revealing that argH and argG knockdowns trigger highly diverse metabolomic perturbations. This scalable framework overcomes batch culture limitations, ensuring precise temporal control for accurate phenotypic characterization and reliable functional genomics. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/709552v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@c6795dorg.highwire.dtl.DTLVardef@49f52dorg.highwire.dtl.DTLVardef@17f5d80org.highwire.dtl.DTLVardef@d3bbca_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2025

Comparative genomic assessment of the Cupriavidus necator species for one-carbon based biomanufacturing

The transition from a petroleum-based manufacturing to biomanufacturing is an important step towards a sustainable bio-economy. In particular biotechnological processes which use one carbon (C1) compounds as feedstock represent an interesting avenue. Many bacterial species evolved naturally to thrive on such compounds, among them Cupriavidus necator, which has been studied in the past due to its range of metabolic capabilities in utilization and production of compounds of interest. Cupriavidus necator strain H16 is the reference laboratory strain for this species and by far the most extensively studied. In contrast, research efforts and genomic characterization of other strains within this species have been limited and sporadic. Therefore, the genomic diversity and full metabolic potential across the broader species remain poorly understood. In this work, we collected publicly available genomes along with newly sequenced ones. From a collection of 44 genomes we curated a final collection of 22 genomes deemed to be C. necator. We examined hallmark metabolic functions, including carbon dioxide fixation, formate assimilation, and hydrogen utilization. We identified methylation motifs and restriction modification systems. Finally, strains ATCC 25207, TA06, and 1978 are proposed as candidate strains of interest based on their genomic make-up and observations from literature. This work provides a comprehensive genomic resource for the C. necator species, facilitating its development as a biomanufacturing platform and advancing our understanding of its metabolic diversity and potential applications. ImportanceThe green transition from petroleum-based manufacturing to a biomanufacturing economy requires new solutions. One of these is the development of bacterial platforms for production of valuable chemicals, in particular from CO2 and derived molecules. In this context, Cupriavidus necator is one of the most studied platform strains, although the genomic potential of this species has been seldom explored. This work provides a curated set of C. necator genomes, collected from public repositories and additional newly sequenced genomes. Through multiple analyses, C. necator ATCC 25207, TA06, and 1978 are proposed as strains of interest for further use. These findings lay the groundwork for advancing C. necator as a key organism in sustainable biomanufacturing, highlighting its potential for efficient carbon fixation, formate assimilation, and hydrogen utilization. The identification of methylation motifs and restriction modification systems further supports genetic engineering efforts, making these strains highly valuable for future biotechnological applications.

microbiology↗

bioRxiv2023

Pangenome evaluation of gene essentiality in Streptococcus pyogenes

Populations of bacterial pathogens are made of strains that often have variable gene content, termed the pangenome. Variations in the genetic makeup of a single strain can alter bacterial physiology and fitness in response to different environmental stimuli. To define biologically relevant genes within a genome, genome-wide knockout transposon mutant libraries have been used to identify genes essential for survival or virulence in a particular strain. Such phenotypic studies have been applied in four different genotypes of the major human pathogen Streptococcus pyogenes, yet challenges exist in comparing results across studies conducted in different genetic backgrounds and conditions. To advance genotype-phenotype inferences within a population genomic framework of 250 S. pyogenes reference genomes, we systematically re-analysed publicly available transposon sequencing datasets from S. pyogenes using a transposon sequencing specific analysis pipeline, Transit. Across 4 genetic backgrounds and 9 phenotypic conditions, 311 genes were highly essential for survival, corresponding to [~]22% of the core genome. Among the 311 genes, functions related to information storage, and processing were overrepresented. Genes associated with cellular processing and signalling were of significantly higher essentiality under in vivo conditions (animal models with differing disease manifestation and site of colonisation) compared to in vitro (varying types of culture media). Finally, essential operons across S. pyogenes genotypes were defined, with an increased number of essential operons detected under in vivo conditions. This study provides an extendible database to which new studies can be added, and a searchable html-based resource to direct future investigations into S. pyogenes population biology. ImportanceStreptococcus pyogenes is a human adapted pathogen occupying restricted ecological niches. Understanding essentiality of genes across different strains and experimental conditions is important to direct research questions and efforts to prevent the large burden of disease caused by S. pyogenes. To this end we systematically reanalysed transposon sequencing studies in S. pyogenes using transposon sequencing specific methods, integrating them into an extendible meta-analysis framework. This provides a repository of gene essentiality in S. pyogenes for the community to guide future phenotypic studies.

genomics↗

bioRxiv2023

Inter-species gene flow drives ongoing evolution of Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging cause of human infection with invasive disease incidence and clinical manifestations comparable to the closely related species, Streptococcus pyogenes. Through systematic genomic analyses of 501 disseminated SDSE strains, we demonstrate extensive overlap between the genomes of SDSE and S. pyogenes. More than 75% of core genes are shared between the two species with one third demonstrating evidence of cross-species recombination. Twenty-five percent of mobile genetic element (MGE) clusters and 16 of 55 SDSE MGE insertion regions were found across species. Assessing potential cross-protection from leading S. pyogenes vaccine candidates on SDSE, 12/34 preclinical vaccine antigen genes were shown to be present in >99% of isolates of both species. Relevant to possible vaccine evasion, six vaccine candidate genes demonstrated evidence of inter-species recombination. These findings demonstrate previously unappreciated levels of genomic overlap between these closely related pathogens with implications for streptococcal pathobiology, disease surveillance and prevention.

microbiology↗

bioRxiv2020

Prophage exotoxins enhance colonization fitness in epidemic scarlet fever-causing Streptococcus pyogenes

The re-emergence of scarlet fever poses a new global public health threat. The capacity of North-East Asian serotype M12 (emm12) Streptococcus pyogenes (group A Streptococcus, GAS) to cause scarlet fever has been linked epidemiologically to the presence of novel prophages, including prophage {Phi}HKU.vir encoding the secreted superantigens SSA and SpeC and the DNase Spd1. Here we report the comprehensive molecular characterization of {Phi}HKU.vir-encoded exotoxins. We demonstrate that streptolysin O (SLO)-induced glutathione efflux from host cellular stores is a previously unappreciated GAS virulence mechanism that promotes SSA release and activity, representing the first description of a thiol-activated bacterial superantigen. Spd1 is required for optimal growth in human blood, confers resistance to neutrophil killing, and degrades neutrophil extracellular traps (NETs). Investigating single, double and triple isogenic knockout mutants of the {Phi}HKU.vir-encoded exotoxins, we find that SpeC and Spd1 act synergistically to facilitate nasopharyngeal colonization in a mouse model. These results offer insight into the etiology and pathogenesis of scarlet fever-causing GAS mediated by phage {Phi}HKU.vir exotoxins.

microbiology↗