Microbial dispersal throgh dead-end cavities

2021 ◽  
Author(s):  
David Scheidweiler ◽  
Ankur Deep Bordoloi ◽  
Pietro de Anna
Keyword(s):  
Porous Media ◽  
Time Lapse ◽  
Breakthrough Curves ◽  
Bacterial Cells ◽  
Dispersal Patterns ◽  
Microbial Life ◽  
Sedimentary Environments ◽  
Escherichia Coli Cells ◽  
Dead End

<p>Predicting dispersal patterns is important to understand microbial life in porous media as soils and sedimentary environments. We studied active and passive dispersal of bacterial cells in porous media characterized by two main pore features: fast channels and dead-end cavities. We combined experiments with microfluidic devices and time-lapse microscopy to track individual bacterial trajectories and measure the breakthrough curves and pore scale bacterial abundance. Escherichia coli cells dispersed more efficiently than the non-motile mutants showing a different retention in the dead-end pores. Our findings highlight the role of diffusion dominated dead-end pores on the dispersal of microorganisms in porous media.</p>

scholarly journals Trait-specific dispersal of bacteria in heterogeneous porous environments: from pore to porous medium scale

2020 ◽  
Vol 17 (164) ◽  
pp. 20200046 ◽  
Author(s):  
David Scheidweiler ◽  
Filippo Miele ◽  
Hannes Peter ◽  
Tom J. Battin ◽  
Pietro de Anna
Keyword(s):  
Preferential Flow ◽  
Cell Attachment ◽  
Flow Direction ◽  
Time Lapse ◽  
Breakthrough Curves ◽  
Porous System ◽  
Dispersal Patterns ◽  
Multi Scale ◽  
Motile Cells ◽  
Hydrodynamic Shear

The dispersal of organisms controls the structure and dynamics of populations and communities, and can regulate ecosystem functioning. Predicting dispersal patterns across scales is important to understand microbial life in heterogeneous porous environments such as soils and sediments. We developed a multi-scale approach, combining experiments with microfluidic devices and time-lapse microscopy to track individual bacterial trajectories and measure the overall breakthrough curves and bacterial deposition profiles: we, then, linked the two scales with a novel stochastic model. We show that motile cells of Pseudomonas putida disperse more efficiently than non-motile mutants through a designed heterogeneous porous system. Motile cells can evade flow-imposed trajectories, enabling them to explore larger pore areas than non-motile cells. While transported cells exhibited a rotation in response to hydrodynamic shear, motile cells were less susceptible to the torque, maintaining their body oriented towards the flow direction and thus changing the population velocity distribution with a significant impact on the overall transport properties. We also found, in a separate set of experiments, that if the suspension flows through a porous system already colonized by a biofilm, P. putida cells are channelled into preferential flow paths and the cell attachment rate is increased. These two effects were more pronounced for non-motile than for motile cells. Our findings suggest that motility coupled with heterogeneous flows can be beneficial to motile bacteria in confined environments as it enables them to actively explore the space for resources or evade regions with unfavourable conditions. Our study also underlines the benefit of a multi-scale approach to the study of bacterial dispersal in porous systems.

scholarly journals Mg-Rich Authigenic Carbonates in Coastal Facies of the Vtoroe Zasechnoe Lake (Southwest Siberia): First Assessment and Possible Mechanisms of Formation

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 763
Author(s):  
Andrey Novoselov ◽  
Alexandr Konstantinov ◽  
Artem Lim ◽  
Katja Goetschl ◽  
Sergey Loiko ◽  
...  
Keyword(s):  
Steppe Zone ◽  
Solute Concentration ◽  
Forest Steppe ◽  
Bacterial Cells ◽  
Authigenic Carbonates ◽  
Sedimentary Environments ◽  
Exopolymeric Substances ◽  
Carbonate Formation ◽  
Mechanisms Of Formation

The formation of Mg-rich carbonates in continental lakes throughout the world is highly relevant to irreversible CO2 sequestration and the reconstruction of paleo-sedimentary environments. Here, preliminary results on Mg-rich carbonate formation at the coastal zone of Lake Vtoroe Zasechnoe, representing the Setovskiye group of water bodies located in the forest-steppe zone of Southwest Western Siberia, are reported. The Setovskiye lakes are Cl−–Na+–(SO42−) type, alkaline, and medium or highly saline. The results of microscopic and mineralogical studies of microbialites from shallow coastal waters of Lake Vtoroe Zasechnoe demonstrated that Mg in the studied lake was precipitated in the form of hydrous Mg carbonates, which occur as radially divergent crystals that form clusters in a dumbbell or star shape. It is possible that hydrous Mg carbonate forms due to the mineralization of exopolymeric substances (EPS) around bacterial cells within the algal mats. Therefore, the Vtoroe Zasechnoe Lake represents a rare case of Mg-carbonates formation under contemporary lacustrine conditions. Further research on this, as well as other lakes of Setovskiye group, is needed for a better understanding of the possible role of biomineralization and abiotic mechanisms, such as winter freezing and solute concentration, in the formation of authigenic Mg carbonate in modern aquatic environments.

Filtration by porous media: a microfluidics approach

2021 ◽  
Author(s):  
filippo miele ◽  
Marco dentz ◽  
Veronica morales ◽  
Pietro de Anna
Keyword(s):  
Porous Media ◽  
Time Lapse ◽  
Breakthrough Curves ◽  
Pore Scale ◽  
Lagrangian Analysis ◽  
Attachment Rate ◽  
Colloid Filtration ◽  
Heavy Tailed ◽  
Set Up ◽  
Continuous Injection

<p>The transport of colloids in porous media is governed by deposition on solid surfaces and pore-scale flow variability. Classical approaches, like colloid filtration theory (CFT), do not capture behaviours observed experimentally, such as non-exponential steady state deposition profiles and heavy tailed BreakThrough Curves (BTC). In the framework of CFT, a key assumption is that the colloid attachment rate <span><span><span><span>𝑘</span></span></span></span> is constant and empirically estimated via a posteriori macroscopic data fitting. We design a novel experimental set-up based on time-lapse microscopy and continuous injection of fluorescent monodisperse colloids into a folded microfluidics device (1mt total length) designed with a controlled level of 2D spatial disorder. This set-up allows us to i) measure both BTC and deposition profile over several orders of magnitude and ii) to perform particle tracking and Lagrangian analysis of single colloid's trajectories. Based on this analysis, we propose a stochastic model that takes into account pore scale heterogeneities in terms of correlation length, velocity and attachment rate distribution, that captures the anomalous behaviour shown by the experimental data.</p>

Effect of dead-end pores on anomalous transport in porous media

2021 ◽  
Author(s):  
Ankur Bordoloi ◽  
David Scheidweiler ◽  
Pietro de Anna
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Breakthrough Curve ◽  
Complex Dynamics ◽  
Breakthrough Curves ◽  
Small Scale ◽  
Complex Flow ◽  
Colloidal Transport ◽  
Dead End ◽  
Long Tails

<p>Heterogeneity in porous media may occur due to non-uniformity in the sizes or the shapes of grains that comprise the medium. We investigate the transport of colloids in a heterogeneous porous medium engineered in microuidic channels and featuring complex grain structures. Using experiment and numerical simulation, we investigate the velocity fields and the breakthrough curves of colloidal transport in a model porous medium by emphasising on the effects of dead-end pores. We characterize the porous structure via image processing and isolate dead-end sites from the remaining pore spaces. The study reveals complex flow structures inside dead-end sites that contribute to the small-scale velocity and long tails in the breakthrough curve. We provide a statistical model to capture the complex dynamics of the breakthrough curve.</p>

Role of Flow Enhancement Network during Filling of Fibrous Porous Media

2005 ◽  
Vol 8 (3) ◽  
pp. 281-297 ◽  
Author(s):  
B. Markicevic ◽  
D. Litchfield ◽  
D. Heider ◽  
Suresh G. Advani
Keyword(s):  
Porous Media ◽  
Fibrous Porous Media ◽  
Flow Enhancement

Capillary Imbibition Dynamics in Porous Media

2014 ◽  
Author(s):  
Swayamdipta Bhaduri ◽  
Pankaj Sahu ◽  
Siddhartha Das ◽  
Aloke Kumar ◽  
Sushanta K. Mitra
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Paper Strip ◽  
Capillary Imbibition ◽  
Flow Physics ◽  
Fundamental Understanding ◽  
Paper Based Microfluidics ◽  
To Come

The phenomenon of capillary imbibition through porous media is important both due to its applications in several disciplines as well as the involved fundamental flow physics in micro-nanoscales. In the present study, where a simple paper strip plays the role of a porous medium, we observe an extremely interesting and non-intuitive wicking or imbibition dynamics, through which we can separate water and dye particles by allowing the paper strip to come in contact with a dye solution. This result is extremely significant in the context of understanding paper-based microfluidics, and the manner in which the fundamental understanding of the capillary imbibition phenomenon in a porous medium can be used to devise a paper-based microfluidic separator.

Combined time-lapse magnetic resonance imaging and modeling to investigate colloid deposition and transport in porous media

2017 ◽  
Vol 123 ◽  
pp. 12-20 ◽  
Author(s):  
Alizée P. Lehoux ◽  
Pamela Faure ◽  
François Lafolie ◽  
Stéphane Rodts ◽  
Denis Courtier-Murias ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Porous Media ◽  
Magnetic Resonance ◽  
Time Lapse ◽  
Resonance Imaging ◽  
Transport In Porous Media ◽  
Colloid Deposition

scholarly journals Spo0A Suppresses sin Locus Expression in Clostridioides difficile

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Babita Adhikari Dhungel ◽  
Revathi Govind
Keyword(s):  
Diarrheal Disease ◽  
Toxin Production ◽  
The United States ◽  
Upstream Region ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Master Regulator ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR′ (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI. However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile. IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.

The Role of Porous Media in Homogenization of High Pressure Diesel Fuel Spray Combustion

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Navid Shahangian ◽  
Damon Honnery ◽  
Jamil Ghojel
Keyword(s):  
High Pressure ◽  
Porous Media ◽  
High Speed ◽  
Fuel Spray ◽  
Compression Ignition Engines ◽  
System Pressure ◽  
Novel Approach ◽  
Air Mixing ◽  
The Media

Interest is growing in the benefits of homogeneous charge compression ignition engines. In this paper, we investigate a novel approach to the development of a homogenous charge-like environment through the use of porous media. The primary purpose of the media is to enhance the spread as well as the evaporation process of the high pressure fuel spray to achieve charge homogenization. In this paper, we show through high speed visualizations of both cold and hot spray events, how porous media interactions can give rise to greater fuel air mixing and what role system pressure and temperature plays in further enhancing this process.

scholarly journals Stochasticity in Colonial Growth Dynamics of Individual Bacterial Cells

2013 ◽  
Vol 79 (7) ◽  
pp. 2294-2301 ◽  
Author(s):  
Konstantinos P. Koutsoumanis ◽  
Alexandra Lianou
Keyword(s):  
Kinetic Parameters ◽  
Single Cells ◽  
Growth Curves ◽  
Growth Dynamics ◽  
Time Lapse ◽  
Initial Population ◽  
Bacterial Cells ◽  
Stochastic Growth ◽  
Bacterial Populations ◽  
Content Type

ABSTRACTConventional bacterial growth studies rely on large bacterial populations without considering the individual cells. Individual cells, however, can exhibit marked behavioral heterogeneity. Here, we present experimental observations on the colonial growth of 220 individual cells ofSalmonella entericaserotype Typhimurium using time-lapse microscopy videos. We found a highly heterogeneous behavior. Some cells did not grow, showing filamentation or lysis before division. Cells that were able to grow and form microcolonies showed highly diverse growth dynamics. The quality of the videos allowed for counting the cells over time and estimating the kinetic parameters lag time (λ) and maximum specific growth rate (μmax) for each microcolony originating from a single cell. To interpret the observations, the variability of the kinetic parameters was characterized using appropriate probability distributions and introduced to a stochastic model that allows for taking into account heterogeneity using Monte Carlo simulation. The model provides stochastic growth curves demonstrating that growth of single cells or small microbial populations is a pool of events each one of which has its own probability to occur. Simulations of the model illustrated how the apparent variability in population growth gradually decreases with increasing initial population size (N0). For bacterial populations withN0of >100 cells, the variability is almost eliminated and the system seems to behave deterministically, even though the underlying law is stochastic. We also used the model to demonstrate the effect of the presence and extent of a nongrowing population fraction on the stochastic growth of bacterial populations.

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