Phage co-transport with hyphal-riding bacteria fuels bacterial invasion in a water-unsaturated microbial model system

Nonmotile microorganisms often enter new habitats by co-transport with motile microorganisms. Here, we report that also lytic phages can co-transport with hyphal-riding bacteria and facilitate bacterial colonization of a new habitat. This is comparable to the concept of biological invasions in macroecology. In analogy to invasion frameworks in plant and animal ecology, we tailored spatially organized, water-unsaturated model microcosms using hyphae of Pythium ultimum as invasion paths and flagellated soil-bacterium Pseudomonas putida KT2440 as carrier for co-transport of Escherichia virus T4. P. putida KT2440 efficiently dispersed along P. ultimum to new habitats and dispatched T4 phages across air gaps transporting ≈0.6 phages bacteria−1. No T4 displacement along hyphae was observed in the absence of carrier bacteria. If E. coli occupied the new habitat, T4 co-transport fueled the fitness of invading P. putida KT2440, while the absence of phage co-transport led to poor colonization followed by extinction. Our data emphasize the importance of hyphal transport of bacteria and associated phages in regulating fitness and composition of microbial populations in water-unsaturated systems. As such co-transport seems analogous to macroecological invasion processes, hyphosphere systems with motile bacteria and co-transported phages could be useful models for testing hypotheses in invasion ecology.

Phage co-transport with hyphal-riding bacteria fuels bacterial invasion in water-unsaturated microbial ecosystems

Non-motile microbes enter new habitats often by co-transport with motile microorganisms. Here, we report on the ability of hyphal-riding bacteria to co-transport lytic phages and utilize them as "weapons" during colonization of new water-unsaturated habitats. This is comparable to the concept of biological invasions in macroecology. In analogy to invasion frameworks in plant and animal ecology, we tailored spatially organized, water-unsaturated model microcosms using hyphae of Pythium ultimum as invasion paths and flagellated soil-bacterium Pseudomonas putida KT2440 as carrier for co-transport of Escherichia virus T4. P. putida KT2440 efficiently dispersed along P. ultimum to new habitats and dispatched T4 phages across air gaps transporting ≈ 0.6 phages bacteria-1. No T4 displacement along hyphae was observed in the absence of carrier bacteria. If E. coli occupied the new habitat, T4 co-transport fueled the fitness of invading P. putida KT2440, while the absence of phage co-transport led to poor colonization followed by extinction. Our data emphasize the importance of hyphal transport of bacteria and associated phages in regulating fitness and composition of microbial populations in water-unsaturated systems. As such co-transport mirrors macroecological invasion processes, we recommend hyphosphere systems with motile bacteria and co-transported phages as models for testing hypotheses in invasion ecology.

Investigation of the relationship between wave action and the transport of bacteria in freshwater : implications for the management of aquatic and human health risk

The sampling regime used to monitor the microbiological quality of water typically involves the collection of whole water samples, where bacteria are assumed to be planktonic. This practice ignores sedimentary pathogen sources and highlights the lack of understanding regarding the effect of shear stress on the erosion of bacteria from sediment particles. This study utilized a wave flume and an environmental test bacterial strain to examine the effect of increasing wave energy on bacterial loading and the partitioning of free-floating and floc-associated bacteria in water. A positive correlation was found between wave energy, total suspended solids, and bacterial loading in water. Experiments examining free-floating and floc-associated bacteria under low (0.60 N/s) and high (5.35 N/s) wave energy demonstrated the importance of floc as a vector for the transport of bacteria. These results imply that current beach sampling and analysis methods may not reflect overall beach water quality.

Investigation of the relationship between wave action and the transport of bacteria in freshwater : implications for the management of aquatic and human health risk

The sampling regime used to monitor the microbiological quality of water typically involves the collection of whole water samples, where bacteria are assumed to be planktonic. This practice ignores sedimentary pathogen sources and highlights the lack of understanding regarding the effect of shear stress on the erosion of bacteria from sediment particles. This study utilized a wave flume and an environmental test bacterial strain to examine the effect of increasing wave energy on bacterial loading and the partitioning of free-floating and floc-associated bacteria in water. A positive correlation was found between wave energy, total suspended solids, and bacterial loading in water. Experiments examining free-floating and floc-associated bacteria under low (0.60 N/s) and high (5.35 N/s) wave energy demonstrated the importance of floc as a vector for the transport of bacteria. These results imply that current beach sampling and analysis methods may not reflect overall beach water quality.

The influence of motility on bacterial accumulation in a microporous channel

We study the transport of bacteria in a porous media modeled by a square channel containing one cylindrical obstacle via molecular dynamics simulations coupled to a lattice Boltzmann fluid.

Swimming-induced non-Fickian transport of bacteria in porous media

<p>Progress in experimental techniques and imaging methods have led to a leap in the understanding of <br>microscopic transport and swimming mechanisms of motile particles in porous media. This is very different <br>for the understanding and characterization of large scale transport behaviors, which result from the <br>interaction of motility with flow and medium heterogeneity, and the upscaling of microscale behaviors. <br>Only few works have investigated large scale dispersion of active particles in porous media, <br>which mainly operate in the framework of Brownian dynamics and effective dispersion or <br>are completely data driven. In this work, we use the particle tracking data of Creppy et al. [1] <br>to derive the stochastic dynamics of small scale particle motion due to hydrodynamic flow variability <br>and the swimming activity of bacteria. These stochastic rules are used to derive a <br>continous time random walk (CTRW) based model for bacteria motion. The CTRW naturally accounts for <br>persistent advective motion along streamlines [2]. In this framework, particle motility is modeled <br>through a subordinated Ornstein-Uhlenbeck process that accounts for the impact of rotational diffusion on <br> particle motion in the fluid, and a compound Poisson process that accounts for the motion toward and around <br>grains. The upscaled transport framework can be parameterized by the distribution of the Eulerian <br>pore velocities, and the motility rules of the bacteria. The model predicts the propagators of the <br>ensemble of bacteria as well as their center of mass position and dispersion for bacteria transport under different<br>flow rates. </p><p>[1] A. Creppy, E. Clément, C. Douarche, M. V. D’Angelo, and H. Auradou. Effect of motility on the transport of bacteria populations through a porous medium. Phys. Rev. Fluids, 4(1), 2019.</p><p>[2] M. Dentz, P. K. Kang, A. Comolli, T. Le Borgne, and D. R. Lester. Continuous time random walks for the evolution of Lagrangian velocities. Physical Review Fluids, 1(7):074004, 2016.</p>

Vesicoureteric reflux

The term vesicoureteric reflux (VUR) describes the retrograde flow of urine from the bladder into the upper urinary tract. VUR is not a disease entity in its own right. Nevertheless, it has the potential to cause significant morbidity by preventing effective emptying of the urinary tract and by facilitating the transport of bacteria into the upper tract and renal parenchyma. Mechanisms of renal damage associated with VUR include pyelonephritic scarring and congenital dysplasia or hypoplasia. The long-term complications of pyelonephritic scarring may include hypertension, renal failure, and an increased risk of complications during pregnancy. VUR of mild or moderate severity is best managed conservatively and surgical intervention is generally reserved for failed medical management and high grade or complex VUR. Although the introduction of endoscopic correction has revolutionized surgical management, there remains a role for open surgery for the correction of higher grades of reflux.