scholarly journals Life in a Droplet: Microbial Ecology in Microscopic Surface Wetness

2021 ◽  
Vol 12 ◽  
Author(s):  
Tomer Orevi ◽  
Nadav Kashtan
Keyword(s):  
Microbial Ecology ◽  
Response Competition ◽  
Genetic Material ◽  
Liquid Films ◽  
Bulk Liquid ◽  
Specific Level ◽  
Surface Wetness ◽  
Microbial Life ◽  
Antibiotic Response ◽  
Microscopic Surface

While many natural and artificial surfaces may appear dry, they are in fact covered by thin liquid films and microdroplets invisible to the naked eye known as microscopic surface wetness (MSW). Central to the formation and the retention of MSW are the deliquescent properties of hygroscopic salts that prevent complete drying of wet surfaces or that drive the absorption of water until dissolution when the relative humidity is above a salt-specific level. As salts are ubiquitous, MSW occurs in many microbial habitats, such as soil, rocks, plant leaf, and root surfaces, the built environment, and human and animal skin. While key properties of MSW, including very high salinity and segregation into droplets, greatly affect microbial life therein, it has been scarcely studied, and systematic studies are only in their beginnings. Based on recent findings, we propose that the harsh micro-environment that MSW imposes, which is very different from bulk liquid, affects key aspects of bacterial ecology including survival traits, antibiotic response, competition, motility, communication, and exchange of genetic material. Further research is required to uncover the fundamental principles that govern microbial life and ecology in MSW. Such research will require multidisciplinary science cutting across biology, physics, and chemistry, while incorporating approaches from microbiology, genomics, microscopy, and computational modeling. The results of such research will be critical to understand microbial ecology in vast terrestrial habitats, affecting global biogeochemical cycles, as well as plant, animal, and human health.

scholarly journals Inherent protection of bacteria from beta-lactam antibiotics by wet-dry cycles with microscopic surface wetness

2020 ◽  
Author(s):  
Yana Beizman-Magen ◽  
Maor Grinberg ◽  
Tomer Orevi ◽  
Nadav Kashtan
Keyword(s):  
Model Organism ◽  
Liquid Films ◽  
Interspecies Interactions ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Surface Wetness ◽  
Beta Lactam Antibiotics ◽  
Hygroscopic Salts ◽  
Antibiotic Response ◽  
Microscopic Surface

AbstractA large portion of bacterial life occurs on surfaces that are not constantly saturated with water and experience recurrent wet-dry cycles. While soil, plant leaves and roots, and many indoor surfaces may appear dry when not saturated with water, they are in fact often covered by thin liquid films and microdroplets, invisible to the naked eye, known as microscopic surface wetness (MSW). Such MSW, resulting from the condensation of water vapor to hygroscopic salts, is ubiquitous yet largely underexplored. A wide variety of antibiotics are abundant in environments where MSW occurs, yet little is known about bacterial response to antibiotics in wet-dry cycles and under MSW conditions. Using E. coli as a model organism, we show, through a combination of experiments and computational modeling, that bacteria are considerably more protected from beta-lactams under wet-dry cycles with MSW phases, than they are under constantly wet conditions. This is due to the combined effect of several mechanisms, including tolerance triggered by inherent properties of MSW, i.e., high salt concentrations and slow cell growth, and the deactivation of antibiotics due to physicochemical properties of MSW. Remarkably, we also find evidence for a cross-protection effect, where addition of lethal doses of antibiotic before drying significantly increases cells’ survival under MSW. As wet-dry cycles with MSW and beta-lactams, as well as other antibiotics, are common in vast terrestrial microbial habitats, our findings are expected to have significant implications for how we understand antibiotic response, population dynamics, and interspecies interactions in these globally important microbial ecosystems.

scholarly journals Evaporation with the formation of chains of liquid bridges

2018 ◽  
Vol 837 ◽  
pp. 703-728 ◽  
Author(s):  
C. Chen ◽  
P. Joseph ◽  
S. Geoffroy ◽  
M. Prat ◽  
P. Duru
Keyword(s):  
Porous Media ◽  
Evaporation Rate ◽  
Phase Distribution ◽  
Pore Space ◽  
Liquid Films ◽  
Bulk Liquid ◽  
Pure Liquid ◽  
Liquid Bridges ◽  
Flat Plates ◽  
Evaporation Kinetics

The objective of the present work is to study the drying of a quasi-two-dimensional model porous medium, hereafter called the micromodel, initially filled with a pure liquid. The micromodel consists of cylinders measuring $50~\unicode[STIX]{x03BC}\text{m}$ in both height and diameter, radially arranged as a set of neighbouring spirals and sandwiched between two horizontal flat plates. As drying proceeds, air invades the pore space and elongated liquid films trapped by capillary forces form along the spirals. These films consist of ‘chains’ of liquid bridges connecting neighbouring cylinders. They provide hydraulic connectivity between the central bulk liquid cluster and the external rim of the cylinder pattern, where evaporation takes place during a first constant-evaporation-rate drying stage. The first goal of the present paper is to describe experimentally the phase distribution during drying, notably the evolution of liquid films, which controls the evaporation kinetics (e.g. the depinning of the films from the external rim signals the end of the constant-evaporation-rate period). Then, a viscocapillary model for the drying process is presented. It is based on numerical simulations of a liquid film capillary shape and viscous flow within a film. The model shows a reasonably good agreement with the experimental data. Thus, the present study is a step towards direct modelling of the effect of films on the drying of more complex porous media (e.g. packing of beads) and should be of interest for multiphase flow applications in porous media, involving transport within liquid films.

Tension of liquid films and contact angles between film and bulk liquid

1968 ◽  
Vol 64 ◽  
pp. 2213 ◽  
Author(s):  
A. Scheludko ◽  
B. Radoev ◽  
T. Kolarov
Keyword(s):  
Liquid Films ◽  
Contact Angles ◽  
Bulk Liquid

scholarly journals Applications of Metagenomics for Unrevealing the Extended Horizons of Microbiota Prevalence from Soil to Human Health

2021 ◽  
Vol 15 (1) ◽  
pp. 177-187
Author(s):  
Vrishty Sharma ◽  
Muneer Ahmad Malla ◽  
Rajesh Kumar Kori ◽  
Rajesh Singh Yadav ◽  
Zaffar Azam
Keyword(s):  
Dna Sequencing ◽  
High Performance ◽  
Genetic Material ◽  
Microbial Life ◽  
Adverse Conditions ◽  
Culture Independent ◽  
Depth Study ◽  
Extensive Information ◽  
And Function ◽  
Performance Computing

Phylogenetic analysis of different ecosystems has shown that the number of microbial communities in a single sample exceeds their cultured counterparts. Microbes have been found throughout nature and can thrive in adverse conditions. Besides inhabiting diverse environments, they also play a key role in the maintenance of the ecosystem. Most of these microbes are either unculturable or difficult to culture with conventional culturing methods. Metagenomics is an emerging field of science that has been in the light for a decade and offers a potential way to assess microbial diversity. The development of metagenomics opens new ways to study genetic material directly from the environmental samples. DNA sequencing and synthesis technologies are making it possible to read and write entire genomes. The huge amount of data obtained from genome sequencing inevitably requires bioinformatics tools to handle and further process them for analysis. Advances in DNA sequencing and high-performance computing have brought about exemplar improvement in metagenomics, allowing in-depth study of the largely unexplored frontier of microbial life. This culture-independent method provides extensive information regarding the structure, composition, and function of the diverse assemblages of the environmental microbes. The current review presents an overview of the technical aspects of metagenomics along with its diverse applications.

Molecular-Level Modeling of Interfacial Phenomena: Use of Molecular Dynamics Simulations in Tandem With Statistical Thermodynamics Models

2007 ◽  
Author(s):  
Van P. Carey
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Molecular Level ◽  
Md Simulations ◽  
Statistical Thermodynamics ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Interfacial Phenomena ◽  
Bulk Liquid ◽  
Interfacial Region

Nanoscale aspects of interfacial phenomena can be critically import in convective vaporization and condensation in nanochannels or microchannels. Molecular dynamics (MD) simulations have been extensively used to model and explore the physics of interfacial phenomena at the molecular level. Efforts to improve MD simulations have often focused on development of more physically realistic interaction potentials used to model intermolecular force interactions, or on development of more efficient computing strategies. An important, and often overlooked aspect of MD simulations is the role that theoretical models from statistical thermodynamics can play in MD simulations. This paper argues that use of alternate statistical thermodynamics models, and unconventional strategies for using them, can be effective ways of enhancing MD simulations. The advantages of these types of approaches are explored in the context of three recent MD simulation studies of interfacial region thermophysics that have made use of statistical thermodynamics theory in novel ways. Examples considered include studies of the interfacial region between bulk liquid and vapor phases, thin liquid films on solid surfaces, and stability free thin liquid films. These examples illustrate ways that MD simulations can be combined with other models to enhance computational efficiency or extract more information from the MD simulation results. Successful strategies for implementing these types of scheme are examined, and their general applicability is assessed.

scholarly journals Genome Analysis of Acinetobacter lwoffii Strains Isolated from Permafrost Soils Aged from 15 Thousand to 1.8 Million Years Revealed Their Close Relationships with Present-Day Environmental and Clinical Isolates

Biology ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 871
Author(s):  
Andrey L. Rakitin ◽  
Alexandra Y. Ermakova ◽  
Alexey V. Beletsky ◽  
Mayya Petrova ◽  
Andrey V. Mardanov ◽  
...  
Keyword(s):  
Genome Analysis ◽  
Genetic Material ◽  
Antibiotic Resistance Genes ◽  
Clinical Isolates ◽  
Natural Habitats ◽  
Genetic Characteristics ◽  
Microbial Life ◽  
Genome Wide ◽  
A Genome ◽  
Permafrost Soils

Microbial life can be supported at subzero temperatures in permafrost up to several million years old. Genome analysis of strains isolated from permafrost provides a unique opportunity to study microorganisms that have not previously come into contact with the human population. Acinetobacter lwoffii is a typical soil bacterium that has been increasingly reported as hospital pathogens associated with bacteremia. In order to identify the specific genetic characteristics of ancient permafrost-conserved strains of A. lwoffii and their differences from present-day clinical isolates, we carried out a genome-wide analysis of five strains of A. lwoffii isolated from permafrost aged from 15 thousand to 1.8 million years. Surprisingly, we did not identify chromosomal genetic determinants that distinguish permafrost strains from clinical A. lwoffii isolates and strains from other natural habitats. Phylogenetic analysis based on whole genome sequences showed that permafrost strains do not form a separate cluster and some of them are most closely related to clinical isolates. The genomes of clinical and permafrost strains contain similar mobile elements and prophages, which indicates an intense horizontal transfer of genetic material. Comparison of plasmids of modern and permafrost strains showed that plasmids from the modern strains are enriched with antibiotic resistance genes, while the content of genes for resistance to heavy metals and arsenic is nearly the same. The thawing of permafrost caused by global warming could release new potentially pathogenic strains of Acinetobacter.

scholarly journals Mineral Facilitated Horizontal Gene Transfer: A New Principle for Evolution of Life?

2017 ◽  
Author(s):  
K.K. Sand ◽  
S. Jelavić
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Genetic Material ◽  
Microbial Life ◽  
Earth’S Atmosphere ◽  
Mineral Associations ◽  
Evolution Of Life ◽  
Earth's Atmosphere

AbstractA number of studies have highlighted that adsorption to minerals increases DNA longevity in the environment. Such DNA-mineral associations can essentially serve as pools of genes that can be stored across time. Importantly, this DNA is available for incorporation into alien organisms through the process of horizontal gene transfer. Here we argue that minerals hold an unrecognized potential for successfully transferring genetic material across environments and timescales to distant organisms and hypothesize that this process has significantly influenced the evolution of life. Our hypothesis is illustrated in the context of the evolution of early microbial life and the oxygenation of the Earth’s atmosphere and offers an explanation for observed outbursts of evolutionary events caused by horizontal gene transfer.

scholarly journals Bacterial survival in microscopic surface wetness

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Maor Grinberg ◽  
Tomer Orevi ◽  
Shifra Steinberg ◽  
Nadav Kashtan
Keyword(s):  
Cell Survival ◽  
Bacterial Species ◽  
Aggregate Size ◽  
Bacterial Survival ◽  
Plant Leaves ◽  
Surface Wetness ◽  
Leaf Surfaces ◽  
Bacterial Aggregates ◽  
Microbial Habitat ◽  
Microscopic Surface

Plant leaves constitute a huge microbial habitat of global importance. How microorganisms survive the dry daytime on leaves and avoid desiccation is not well understood. There is evidence that microscopic surface wetness in the form of thin films and micrometer-sized droplets, invisible to the naked eye, persists on leaves during daytime due to deliquescence – the absorption of water until dissolution – of hygroscopic aerosols. Here, we study how such microscopic wetness affects cell survival. We show that, on surfaces drying under moderate humidity, stable microdroplets form around bacterial aggregates due to capillary pinning and deliquescence. Notably, droplet-size increases with aggregate-size, and cell survival is higher the larger the droplet. This phenomenon was observed for 13 bacterial species, two of which – Pseudomonas fluorescens and P. putida – were studied in depth. Microdroplet formation around aggregates is likely key to bacterial survival in a variety of unsaturated microbial habitats, including leaf surfaces.

scholarly journals Author response: Bacterial survival in microscopic surface wetness

2019 ◽  
Author(s):  
Maor Grinberg ◽  
Tomer Orevi ◽  
Shifra Steinberg ◽  
Nadav Kashtan
Keyword(s):  
Author Response ◽  
Bacterial Survival ◽  
Surface Wetness ◽  
Microscopic Surface
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