Onime, J. | Search bioRxiv

bioRxiv2026

Yersinia pseudotuberculosis employs a multifaceted strategy to survive antimicrobials

Microbes have evolved a variety of strategies to survive exposure to naturally occurring and synthetic antimicrobials. These strategies have been investigated extensively in model bacterial organisms, whereas less is known about under explored pathogenic bacteria such as bacteria within the Yersinia genus. In this study we investigated the inhibitory effect and bactericidal activity of antibiotics from five different classes and of the disinfectant hydrogen peroxide against Yersinia pseudotuberculosis, the ancestral species from which Yersinia pestis and Yersinia enterocolitica have emerged. We found that Y. pseudotuberculosis is able to survive exposure to clinical antibiotics and disinfectants by employing a variety of strategies, with persisters and the Eagle effect playing a role in survival to quinolones, tolerance playing a role in survival to ceftriaxone and overexpression of catalases and peroxidases playing a role in survival to hydrogen peroxide. Our findings suggest that future research should focus on informing new, effective ways to treat infections caused by Yersinia species. IMPORTANCEAntimicrobial resistance is routinely investigated by measuring the minimum inhibitory concentration of antimicrobials needed to stop microbial growth. Here we show that the bacterial pathogen Yersinia pseudotuberculosis is not killed when antibiotics and disinfectants are used at these concentrations and that, in some cases, increasing antibiotic concentrations decreases their activity against this bacterium, therefore posing a potential risk to human and animal health.

microbiology↗

bioRxiv2025

Developmental priming increases copper-tolerance in a model fish species via epigenetic-and microbiome-mediated mechanisms

Pollution is a significant threat to aquatic ecosystems globally and, in order to survive, natural populations depend upon their ability to rapidly develop tolerance to chemical stressors. We examined whether early-life priming enhances life-long copper-tolerance in a model fish species via developmental plasticity. Stickleback (Gasterosteus aculeatus) embryos were pre-exposed to a low concentration of copper (10 {micro}g/L) during early development, reared in clean water for nine months alongside a control group, and then exposed to copper (0,10 and 20 {micro}g/L) for 96 h as adults. Priming markedly reduced evidence of copper-toxicity in adult gills at the transcriptional level (including reduced cellular stress response (CSR) and disruption of ion-homeostasis) and increased inducibility of the metal-binding protein, metallothionein. In parallel, we identified epigenetic and microbiome-mediated mechanisms likely contributing to this tolerance. Pre-exposure induced persistent DNA methylation changes, consistent with priming of CSR and ion-homeostasis pathways. We identified enhanced copper-tolerance in the gill microbiota of primed fish that likely also contributed to host tolerance. These findings provide critical evidence for developmental plasticity induced by chemical stressors in animals, highlight the importance of integrated microbiome and epigenetic responses, and enhance our understanding of how natural populations cope with pollution in their environment.

evolutionary biology↗

bioRxiv2025

Altered microRNA Expression Correlates with Reduced TLR2/4-Dependent Periodontal Inflammation and Bone Resorption Induced by Polymicrobial Infection

Periodontitis (PD) is a polymicrobial dysbiotic immuno-inflammatory disease. Toll-like receptors (TLRs) are present on gingival epithelial cells and recognize pathogen-associated molecular patterns (PAMPs) on pathogenic bacteria, induce the secretion of proinflammatory cytokines, and initiate innate and adaptive antigen-specific immune responses to eradicate the invading microbes. Since PD is a chronic inflammatory disease, TLR2/TLR4 plays a vital role in disease pathogenesis and maintaining the periodontium during health. Many factors modulate the TLR-mediated signaling pathway, including specific miRNAs. The present study was designed to characterize the function of TLR2/4 signaling to the miRNA profile after polybacterial infection with Streptococcus gordonii, Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia in C57BL6/J wild-type, TLR2-/-, and TLR4-/- mice (n=16/group) using RT-qPCR. The selection of 15 dominant miRNAs for RT-qPCR analysis was based on prior NanoString global miRNA expression profiling in response to polymicrobial and monobacterial infection. Polybacterial infections established gingival colonization in wild-type, TLR2-/- and TLR4-/- mice with induction of bacterial-specific IgG. A significant reduction in alveolar bone resorption (ABR) and gingival inflammation was observed in the mandibles of TLR2/4-/- mice compared to C57BL6/J wild-type mice (p<0.0001). Periodontal bacteria disseminated from gingival tissue to the multiple organs in wild-type and TLR2-/- mice (heart, lungs, brain, kidney) and limited to heart (F. nucleatum), lungs (P. gingivalis), kidney (T. forsythia) in TLR4-/- mice. The diagnostic potential of miRNAs was assessed by receiver operating characteristic (ROC) curves. Among 15 miRNAs, three were upregulated in C57BL6/J wild-type mice, two in TLR2-/-, and seven in TLR4-/- mice. Notably, the anti-inflammatory miR-146a-5p was consistently upregulated in all the mice. Additionally, miR-15a-5p was upregulated in wild-type and TLR2-/- mice. let-7c-5p was upregulated in TLR4-/- mice and downregulated in the wild-type mice. Multi-species oral bacterial infection alters the TLR2/4 signaling pathways by modulating the expression of several potential biomarker miRNAs in periodontium. IMPORTANCEPeriodontitis is the most prevalent chronic immuno-infectious multispecies dysbiotic disease of the oral cavity. The Toll-like receptors (TLR) provide the first line of defense, one of the best-characterized pathogens-detection systems and play a vital role in recognizing multiple microbial products. Multispecies infection with periodontal bacteria S. gordonii, F. nucleatum, P. gingivalis, T. denticola, and T. forsythia induced gingival inflammation, alveolar bone resorption (ABR) and miRNA expression in the C57BL6/J wild-type mice and whereas infection did not increase significant ABR in the TLR2/4 deficient mice. Among the 15 miRNAs investigated, miR-146a-5p, miR-15a-5p were upregulated in wild-type and TLR2-/- mice and miR-146a-5p, miR-30c-5p, let-7c-5p were upregulated in the TLR4-/- mice compared to sham-infected controls. Notably, inflammatory miRNA miR-146a-5p was upregulated uniquely among the three different infection groups. The upregulated miRNAs (miR-146a, miR-15-a-5p, let-7c-5p) and downregulated miRNAs could be markers for TLRs-mediated induction of periodontitis.

molecular biology↗