Biology subjects

Kochanowski, K.

Publications and source records attributed to Kochanowski, K..

11 recordsLinked to original sources

bioRxiv2026

High-throughput, single-cell-encoded colony imaging reveals infection-linked heterogeneity

Phenotypic heterogeneity within bacterial populations shapes adaptation, antibiotic tolerance, and infection dynamics, yet colony-level quantification remains difficult at scale and on dark/selective media. We present HeteroTyper, an automated, high-throughput time-lapse platform that measures colony phenotypes across >100 plates per run on both transparent and dark media. HeteroTyper includes a ready-to-use computational pipeline that can be deployed on common plate-imaging setups and across agar types, delivering appearance times as a proxy for lag times, growth trajectories, colony size, intensity, and morphology from routine image series. Automated counts closely matched manual counts, supporting accuracy and scalability. Using Yersinia pseudotuberculosis as a model, HeteroTyper resolves phenotypic heterogeneity in vitro, with early and late phases showing broader appearance time distributions than mid-log phases. It also reveals organ-specific heterogeneity in vivo, with mesenteric lymph node isolates displaying the broadest appearance time distributions compared to spleen and liver. Appearance time was negatively associated with final colony size and intensity, linking growth initiation to downstream colony outcomes. Together, these distribution-level measurements indicate that bacterial adaptation during infection is compartmentalized by tissue microenvironments and prior history, and establish HeteroTyper as a practical, generalizable route to quantify infection-relevant phenotypic diversity on solid media at routine, high throughput.

microbiology↗

bioRxiv2026

Genome-scale metabolic model atlas of the zoonotic pathogen Streptococcus suis

Streptococcus suis is a Gram-positive bacterium with a dual role as a commensal member of the porcine nasal microbiota and a pathogen causing systemic disease in pigs and humans. Mounting evidence suggests that metabolism is a key driver of S. suis pathogenicity. Given the species high genetic variability, we hypothesize that differences in metabolic networks could explain the diverse pathogenic phenotypes observed across different strains. To test this, we generated an atlas of over 3000 strain-specific and automatically curated genome-scale metabolic models that cover the breadth of pathogenic and commensal S. suis lineages. Using this model atlas, we performed the first species-level examination of metabolic traits in S. suis. Our simulations, supported by experimental validation, revealed three key insights. First, while metabolic traits are broadly conserved in S. suis, there are nevertheless lineage-dependent differences in amino acid auxotrophies and carbon utilization patterns that point towards distinct in vivo niches. Second, most strains are predicted to grow in different plausible in vivo environments regardless of their virulence phenotype, suggesting that metabolism is a weak barrier to systemic infection. Third, by systematically predicting reaction essentiality in more than 15 million reaction-strain-condition combinations, we identify a subset of 17 reactions, largely in nucleotide metabolism, that are conditionally essential in vivo and may serve as new targets for the development of new antimicrobials or vaccines. Overall, this study provides a valuable new resource for broadly examining S. suis metabolism and its role in pathogenicity.

Systems Biology↗

bioRxiv2026

In vitro efficacy of synthetic antimicrobial peptide SET-M33 against poultry isolates with diverse antimicrobial resistance phenotypes

Antimicrobial resistance is an impactful One Health issue. One of its drivers is the extensive use of antibiotics in both human and animal production systems, and despite regulatory restrictions on antibiotic use in poultry farming, antimicrobial resistance remains a major challenge. Consequently, animals are at higher risk of harder-to-treat diseases and play a role as resistance reservoirs, highlighting the need for alternative antimicrobial strategies. Towards this end, antimicrobial peptides (AMPs) have emerged as promising candidates due to their broad-spectrum activity and lower propensity to induce resistance. However, the effectiveness of AMPs against poultry pathogens, and in particular multi drug-resistant strains, is largely unclear. To tackle this question, we evaluated the synthetic AMP SET-M33 against four species of clinically relevant pathogens in poultry, namely Escherichia coli, Salmonella enterica, Enterococcus faecalis and Enterococcus cecorum. Using a panel of 141 field isolates, we found that SET-M33 broadly inhibited bacterial growth at low micromolar concentrations (median MICs of 2.5 M and 5 M for Gram-negative and Gram-positive strains, respectively), including in multi drug-resistant isolates. To examine the potential impact of SET-M33 on the host, we established a new in vitro co-cultivation system using chicken intestinal organoids. We found that SET-M33 retains its antimicrobial activity in organoid-microbe co-cultures at concentrations that preserved host viability. These findings demonstrate the potential of SET-M33 as a new antimicrobial agent against pathogens in poultry.

microbiology↗

bioRxiv2025

Airway organoids reveal patterns of Influenza A tropism and adaptation in wildlife species

Identifying animal species that are susceptible to the plethora of existing and emerging viruses is critical for predicting and containing disease outbreaks. Current efforts to assess viral tropism largely rely on experimental infection models, but such experiments are logistically and ethically infeasible for many wildlife species. To tackle this challenge, we developed a panel of airway organoids from ten taxonomically diverse wildlife and livestock species and evaluated their susceptibility to influenza viruses of mammalian (pH1N1) and avian (H5N1) origin. Our analyses revealed large species-specific differences in infection rate and cytopathogenicity that aligned with known in vivo data and field observations. Furthermore, we demonstrated that this organoid panel can serve as a powerful tool to elucidate receptor-binding mechanisms, viral dynamics, and early host adaptation in poorly characterized animal species. In summary, this work provides a robust and ethically viable approach for evaluating viral tropism and adaptation in wildlife species, and fills a critical gap in current pandemic preparedness, zoonotic disease surveillance, and wildlife conservation efforts.

microbiology↗

bioRxiv2025

SET-M33 peptide as a selective in vitro antimicrobial agent against the porcine respiratory pathogen Glaesserella parasuis

As we face the threat from bacterial pathogens that are resistant to many conventional antibiotics, many current research efforts focus on expanding our arsenal of antimicrobial compounds. However, identifying use cases in which such new antimicrobials can effectively target pathogens while minimizing collateral damage in the commensal microbiota remains a challenge. To tackle this challenge, we focused on one new antimicrobial, the synthetic antimicrobial peptide SET-M33, and examined its ability to target porcine respiratory pathogens and a collection of porcine commensal nasal microbiota members in vitro. Our experiments revealed three key results. First, there were large differences in SET-M33 sensitivity across the tested strains. In particular, pathogenic Glaesserella parasuis was highly sensitive to SET-M33 at concentrations that did not affect the growth of most commensal strains. Second, some of the tested commensal strains (i.e. Rothia nasimurium and Staphylococcus aureus) were able to inactivate SET-M33 during in vitro cultivation. Third, despite this potential for SET-M33 inactivation by commensal strains, SET-M33 was still able to selectively eliminate pathogenic G. parasuis from in vitro co-cultures that also contained R. nasimurium. Overall, this study highlights the substantial complexity that emerges from the interplay between antimicrobials, pathogens, and commensals, even within a comparatively simple in vitro system, and provides a template for identifying suitable use cases for newly developed antimicrobials.

microbiology↗

bioRxiv2024

In vitro metabolic interaction network of a rationally designed nasal microbiota community

Mounting evidence suggests that metabolite exchange between microbiota members is a key driver of microbiota composition. However, we still know little about the metabolic interaction networks that occur within many microbiota. This is particularly true for the nasal microbiota, and current efforts towards this end are hampered by a lack of microbial consortia that would enable the mapping of metabolic interactions between nasal microbiota members under in vitro conditions. To tackle these issues, we developed the Porcine Nasal Consortium (PNC8), a rationally designed microbial consortium of eight strains representing the most in vivo abundant genera in the nasal microbiota of healthy piglets. We used this consortium to systematically examine the metabolic capabilities of nasal microbiota members, as well as the metabolic interactions occurring between them. We found that PNC8 strains differ substantially in their metabolic pathway repertoire and ability to grow across various in vitro conditions. Nevertheless, spent-media experiments revealed that most metabolic interactions between PNC8 strains are negative, and exometabolomics data pointed to co-depletion of sugars as a key driver of this interaction network. Finally, direct co-cultivation experiments showed that, as a result of this largely negative metabolic interaction network, competition is common among pairs of PNC8 strains and leads to a complex competition hierarchy in which only few strains are able to consistently outcompete all others. Overall, this work provides a valuable resource for studying the nasal microbiota under experimentally tractable in vitro conditions and is a key step towards mapping its metabolic interaction network.

systems biology↗

bioRxiv2024

Porcine Nasal Organoids as a model to study the interactions between the swine nasal microbiota and the host

Interactions between the nasal epithelium, commensal nasal microbiota, and respiratory pathogens play a key role in respiratory infections. Currently there is a lack of experimental models to study such interactions under defined in vitro conditions. Here, we developed a Porcine Nasal Organoid (PNO) system from nasal tissue of pigs as well as from cytological brushes. PNOs exhibited similar structure and cell types than the nasal mucosa, as evaluated by immunostaining. PNOs were inoculated with porcine commensal strains of Moraxella pluranimalium, Rothia nasimurium and the pathobiont Glaesserella parasuis for examining host-commensal-pathogen interactions. All strains adhered to the PNOs, although at different levels. M. pluranimalium and G. parasuis strains stimulated the production of proinflammatory cytokines, whereas R. nasimurium induced the production of IFN{gamma} and diminished the proinflammatory effect of the other strains. Overall, PNOs mimic the in vivo nasal mucosa and can be useful to perform host-microbe interaction studies. In briefInteractions between nasal epithelium, commensal nasal microbiota, and respiratory pathogens play a key role in respiratory infections. We developed porcine nasal organoids to mimic the nasal mucosa and use as a model to study those interactions. Additionally, this development supports the reduction of the number of animals for animal experimentation. HighlightsO_LIFirst generation of Porcine Nasal Organoids (PNOs) from nasal turbinates and swabs C_LIO_LIPNOs recapitulate features of in vivo tissue and maintain self-renewal capacity C_LIO_LIHost-microbe interactions can be studied using the PNO system C_LIO_LIRothia nasimurium inhibits the inflammation induced by other bacteria C_LI

microbiology↗

bioRxiv2023

Gut-associated microbes are present and active in the pig nasal cavity

BackgroundThe nasal microbiota is a key contributor to animal health, and characterizing the nasal microbiota composition is an important step towards elucidating the role of its different members. Efforts to characterize the nasal microbiota composition of domestic pigs and other farm animals frequently report the presence of bacteria that are typically found in the gut, including many anaerobes from the Bacteroidales and Clostridiales orders. However, the in vivo role of these gut-microbiota associated taxa is currently unclear. Here, we tackled this issue by examining the prevalence, origin, and activity of these taxa in the nasal microbiota of piglets. ResultsFirst, analysis of the nasal microbiota of farm piglets sampled in this study, as well as various publicly available data sets, revealed that gut-microbiota associated taxa indeed constitute a substantial fraction of the pig nasal microbiota that is highly variable across individual animals. Second, comparison of herd-matched nasal and rectal samples at amplicon sequencing variant (ASV) level showed that these taxa are largely shared in the nasal and rectal microbiota, suggesting a common origin driven presumably by the transfer of fecal matter. Third, surgical sampling of the inner nasal tract showed that gut-microbiota associated taxa are found throughout the nasal cavity, indicating that these taxa do not stem from contaminations introduced during sampling with conventional nasal swabs. Finally, analysis of cDNA from the 16S rRNA gene in these nasal samples indicated that gut-microbiota associated taxa are indeed active in the pig nasal cavity. ConclusionThis study shows that gut-microbiota associated taxa are not only present, but also active, in the nasal cavity of domestic pigs, and paves the way for future efforts to elucidate the in vivo function of these taxa within the nasal microbiota.

microbiology↗

bioRxiv2020

Dissecting the impact of metabolic environment on three common cancer cell phenotypes

The impact of different metabolic environments on cancer cell behavior is poorly understood. Here, we systematically altered nutrient composition of cell culture media and examined the impact on three phenotypes—drug-treatment survival, cell migration, and lactate overflow—that are frequently studied in cancer cells. These perturbations across diverse metabolic environments revealed simple relationships between cell growth rate and drug-treatment survival or migration. In contrast, lactate overflow was highly sensitive to changes in sugar availability but largely insensitive to changes in amino acid availability, regardless of the growth rate. Further investigation suggested that the degree of lactate overflow across metabolic environments is largely determined by the cells’ ability to maintain high rates of sugar uptake. This study enabled us to elucidate quantitative relationships between metabolic environment and cancer cell phenotypes, which echo empirical growth laws discovered to govern analogous phenotypes in microbes.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cancer biology↗

bioRxiv2020

Stress-Induced Transient Cell Cycle Arrest Coordinates Metabolic Resource Allocation to Balance Adaptive Tradeoffs

The ability of a cell to mount a robust response to an environmental perturbation is paramount to its survival. While cells deploy a spectrum of specialized counter-measures to deal with stress, a near constant feature of these responses is a down regulation or arrest of the cell cycle. It has been widely assumed that this modulation of the cell cycle is instrumental in facilitating a timely response towards cellular adaptation. Here, we investigate the role of cell cycle arrest in the hyperosmotic shock response of the model organism S. cerevisiae by deleting the osmoshock-stabilized cell cycle inhibitor Sic1, thus enabling concurrent stress response activation and cell cycle progression. Contrary to expectation, we found that removal of stress-induced cell cycle arrest accelerated the adaptive response to osmotic shock instead of delaying it. Using a combination of time-lapse microscopy, genetic perturbations and quantitative mass spectrometry, we discovered that unabated cell cycle progression during stress enables the liquidation of internal glycogen stores, which are then shunted into the osmotic shock response to fuel a faster adaptation. Therefore, osmo-adaptation in wild type cells is delayed because cell cycle arrest diminishes the ability of the cell to tap its glycogen stores. However, acceleration of osmo-adaptation in mutant cells that do not arrest comes at the cost of acute sensitivity to a subsequent osmo-stress. This indicates that despite the ostensible advantage faster adaptation poses, there is a trade-off between the short-term benefit of faster adaptation and the vulnerability it poses to subsequent insults. We suggest that cell cycle arrest acts as a carbon flux valve to regulate the amount of material that is devoted to osmotic shock, balancing short term adaptation with long-term robustness.

systems biology↗

bioRxiv2020

Loss of Tet2 affects proliferation and drug sensitivity through altered dynamics of cell-state transitions

A persistent puzzle in cancer biology is how mutations, which neither alter canonical growth signaling pathways nor directly interfere with drug mechanism, can still recur and persist in tumors. One notable example is the loss-of-function mutation of the DNA demethylase Tet2 in acute myeloid leukemias (AMLs) that frequently persists from diagnosis through remission and relapse (Rothenberg-Thurley et al., 2018; Corces-Zimmerman et al., 2014; Nibourel et al., 2010), but whose fitness advantage in the setting of anti-leukemic chemotherapy is unclear. Here we use paired isogenic human AML cell lines to show that Tet2 loss-of-function alters the dynamics of transitions between differentiated and stem-like states. Mathematical modeling and experimental validation reveal that these altered cell-state dynamics can benefit the cell population by slowing population decay during drug treatment and lowering the number of survivor cells needed to re-establish the initial population. These studies shed light on the functional and phenotypic effects of a Tet2 loss-of-function in AML, illustrate how a single gene mutation can alter a cells phenotypic plasticity, and open up new avenues in the development of strategies to combat AML relapse.

systems biology↗