Biology subjects

Wynn, H. K.

Publications and source records attributed to Wynn, H. K..

4 recordsLinked to original sources

bioRxiv2026

Freshwater Microbiomes Shape Viral Inactivation in Continuous Cultures

The high stability of enteric viruses in freshwater increases their risk of waterborne transmission. In aquatic environments, bacteria are known to enhance viral removal and inactivation. However, the differences in viral inactivation across freshwater ecosystems and the influence of community diversity on this process remains poorly understood. Here, we used dilution-to-extinction to generate 64 distinct freshwater communities from three lakes and three aquifers. After establishing freshwater communities in chemostat cultures, each community was challenged with two viruses, coxsackievirus B5 and human adenovirus 2. Both viruses were inactivated more rapidly in lake-derived than in groundwater-derived communities, and adenovirus was inactivated faster than coxsackievirus in both freshwater types. Community-level parameters (cell numbers, richness, evenness) were not significant predictors of viral inactivation. In contrast, differential abundance analyses identified bacterial OTUs associated with inactivation: Acidovorax sp. were associated across sources and Brevundimonas sp., Sphingopyxis sp., and Hydrogenophaga sp. showed source-specific associations. Together, these findings provide new insights into the ecological drivers of viral stability and suggest that viral inactivation may depend more strongly on specific microbial taxa and their ecological context than on overall community diversity. Identifying these associations improves our understanding of the factors governing viral persistence in freshwater environments.

microbiology↗

bioRxiv2026

Distinct kinetics and mechanisms of microbial inactivation of enteric virus revealed by capsid and genome integrity

Enteric viruses are important contaminants of surface waters and a significant burden on public health. In aquatic ecosystems, the stability of these pathogens is differentially impacted by abiotic and biotic stressors, which can exert inactivating effects. Here, we investigated the fate of two enteroviruses, echovirus 11 (E11) and coxsackievirus B5 (CVB5), and one adenovirus, human adenovirus 2 (HAdV2), in lakewater and explored the mechanisms underlying their microbial inactivation. By combining infectivity assays, genome quantification, and capsid integrity analysis, we characterized virus-specific inactivation kinetics and mechanisms and examined the relationship between infectivity loss and capsid structural integrity. We observed rapid, intermediate, and negligible decay for HAdV2, E11, and CVB5, respectively, and confirmed that microbial proteases contribute to their inactivation. In addition, we revealed that loss of capsid structural integrity drives E11 inactivation, but not HAdV2 inactivation. Genome decay did not consistently correlate with loss of infectivity, highlighting the limitations of genome-based detection for assessing the presence of infectious viruses. These findings provide new insights into the mechanisms governing virus inactivation in aquatic environments and emphasize the importance of understanding viral fate when interpreting molecular detection data to assess virus-associated microbial risks.

microbiology↗

bioRxiv2026

Rate of osmotic pressure change in drying saliva microdroplets drives inactivation of surrogate respiratory bacteria

Airborne transmission of respiratory pathogens depends on their ability to remain viable in drying respiratory droplets, yet the physicochemical drivers of bacterial inactivation during droplet evaporation remain poorly quantified. This study combines controlled droplet experiments with physicochemical modeling to investigate how osmotic pressure dynamics influence bacterial survival. Using Escherichia coli and Staphylococcus epidermidis as Gram-negative and Gram-positive surrogates, respectively, we measured viability loss in artificial saliva droplets dried at multiple relative humidities and reconstructed the time-resolved osmotic pressure using the Respiratory Aerosol Model (ResAM). Both organisms remained stable while droplets were liquid but lost viability following efflorescence, when rapid solute concentration changes produced sharp osmotic pressure increases. The extent of inactivation scales log-linearly with the rate of osmotic pressure change around efflorescence: E. coli decays faster than S. epidermidis, and relationships derived in artificial saliva predict survival in independent phosphate-buffered saline experiments. A more rapid drop in humidity led to more severe osmotic shocks and greater inactivation. These results identify the rate of osmotic pressure change during efflorescence as a quantitative, medium-independent predictor of bacterial survival in drying respiratory droplets. ImportanceAirborne infection risk depends on how long microorganisms remain viable in respiratory particles after exhalation, yet the physical mechanisms controlling bacterial survival during droplet drying are not well defined. Evaporation of respiratory droplets concentrates salts and can impose sudden and extreme osmotic stress on microbes, but this process has been difficult to quantify because osmotic pressure cannot be measured directly inside microscopic droplets. Integration of droplet experiments with a physicochemical aerosol model shows that bacterial inactivation is governed primarily by the rate of osmotic pressure increase during droplet efflorescence rather than by static values of humidity or solute concentration alone. This mechanism explains why rapid drying may produce strong inactivation.

microbiology↗

bioRxiv2025

Lognormal distributions capture site-specific variability in enteric virus concentrations in wastewater

As more data on virus concentrations in influent water from wastewater treatment plants (WWTPs) becomes available, establishing best practices for virus measurements, monitoring, and statistical modelling can improve the understanding of virus concentration distributions in wastewater. To support this, we assessed the temporal variability of norovirus, adenovirus, enterovirus, and rotavirus concentrations in influent water across multiple WWTPs in Switzerland, the USA, and Japan. Our findings demonstrate that the lognormal distribution accurately predicts temporal variations in concentrations for all viruses at all sites, outperforming the gamma and Weibull distributions that do not capture high variability. However, important differences in variability and uncertainty were observed across systems, underscoring the need for site-specific assessments. Using lognormal parameters, we identified optimal monitoring frequencies to balance cost-effectiveness and precision. For most sites, weekly monitoring would be sufficient to estimate the annual average concentration of enteric viruses within a 95% confidence interval of 0.5-log10. We examined the mechanistic basis of the lognormal distribution, highlighting processes that drive its prevalence and shape the behavior of its upper tail. By integrating these insights, this study provides a novel statistical foundation for optimizing virus monitoring frameworks and informing public health interventions targeting wastewater systems.

microbiology↗