Bacillus subtilis Kovács, Ákos T.
Trends in microbiology (Regular ed.),
August 2019, 2019-08-00, 20190801, Letnik:
27, Številka:
8
Journal Article
Recenzirano
Bacillus subtilis became the most studied species in the genus Bacillus due to its natural competence for uptake of extracellular DNA that facilitates simple genetic modification and occurrence of ...sporulation, one of the first studied bacterial cell differentiation processes. The dormant spores can survive harsh circumstances (high temperature, desiccation, UV, and γ-radiation), predation by microorganisms and macroorganisms, or even extraterrestrial conditions. B. subtilis can be isolated from various environments, from soil to marine habitats, and utilized in various applications from enzyme production and food fermentation to plant biocontrol. B. subtilis is a model microorganism for studying cell division, protein secretion, surface motility (swimming, swarming, and sliding), biofilm development, attachment to plant root or fungal hyphae, secondary metabolite production, cytoplasm exchange via intercellular nanotubes, extracellular vesicle release, and kin-discrimination.
Standard epidemic models based on compartmental differential equations are investigated under continuous parameter change as external forcing. We show that seasonal modulation of the contact ...parameter superimposed upon a monotonic decay needs a different description from that of the standard chaotic dynamics. The concept of snapshot attractors and their natural distribution has been adopted from the field of the latest climate change research. This shows the importance of the finite-time chaotic effect and ensemble interpretation while investigating the spread of a disease. By defining statistical measures over the ensemble, we can interpret the internal variability of the epidemic as the onset of complex dynamics-even for those values of contact parameters where originally regular behaviour is expected. We argue that anomalous outbreaks of the infectious class cannot die out until transient chaos is presented in the system. Nevertheless, this fact becomes apparent by using an ensemble approach rather than a single trajectory representation. These findings are applicable generally in explicitly time-dependent epidemic systems regardless of parameter values and time scales.
Abstract
We propose a novel method applied to extrasolar planetary dynamics to describe the system stability. The observations in this field serve the measurements mainly of radial velocity, transit ...time, and/or celestial position. These scalar time series are used to build up the high-dimensional phase space trajectory representing the dynamical evolution of planetary motion. The framework of nonlinear time series analysis and Poincaré recurrences allows us to transform the obtained univariate signals into complex networks whose topology carries the dynamical properties of the underlying system. The network-based analysis is able to distinguish the regular and chaotic behaviour not only for synthetic inputs but also for noisy and irregularly sampled real world observations. The proposed scheme does not require neither n-body integration nor best fitting planetary model to perform the stability investigation, therefore, the computation time can be reduced drastically compared to those of the standard numerical methods.
A biofilm is a common life form where bacterial cells crowd together surrounded by an extracellular matrix (ECM). Traditionally, the ECM is considered as a structural material that glues and shields ...the biofilm cells. Here we describe alternative functions of the ECM, highlighting how it benefits microbes beyond the biofilms. Next to protecting free-living cells, the ECM participates in signaling, migration, and genetic exchange either being freely shared with other species or being exclusive to siblings. Considering the structural and recently discovered functions of the ECM, we also attempt to revise its role in sociomicrobiology. In the light of recent findings, the canonical view on ECM as a passive structural material of biofilms should be revisited.
A
bstract
We investigate the QCD phase diagram for nonzero background magnetic fields using first-principles lattice simulations. At the physical point (in terms of quark masses), the thermodynamics ...of this system is controlled by two opposing effects: magnetic catalysis (enhancement of the quark condensate) at low temperature and inverse magnetic catalysis (reduction of the condensate) in the transition region. While the former is known to be robust and independent of the details of the interactions, inverse catalysis arises as a result of a delicate competition, effective only for light quarks. By performing simulations at different quark masses, we determine the pion mass above which inverse catalysis does not take place in the transition region anymore. Even for pions heavier than this limiting value — where the quark condensate undergoes magnetic catalysis — our results are consistent with the notion that the transition temperature is reduced by the magnetic field. These findings will be useful to guide low-energy models and effective theories of QCD.
Summary
Bacteria are able to translocate over surfaces using different types of active and passive motility mechanisms. Sliding is one of the passive types of movement since it is powered by the ...pushing force of dividing cells and additional factors facilitating the expansion over surfaces. In this review, we describe the sliding proficient bacteria that were previously investigated in details highlighting the sliding facilitating compounds and the regulation of sliding motility. Besides surfactants that reduce the friction between cells and substratum, other compounds including exopolysaccharides, hydrophobic proteins, or glycopeptidolipids where discovered to promote sliding. Therefore, we present the sliding bacteria in three groups depending on the additional compound required for sliding. Despite recent accomplishments in sliding research there are still many open questions about the mechanisms underlying sliding motility and its regulation in diverse bacterial species.
Plant–microbiome functioning depends on intricate signaling pathways including plant-derived excretions that induce microbial gene expression. Marc Ongena and his team (Boubsi et al.) dissect how the ...pectin backbone homogalacturonan promotes bacterial differentiation programs of Bacillus velezensis, potentially facilitating its establishment in the rhizosphere.
Plant–microbiome functioning depends on intricate signaling pathways including plant-derived excretions that induce microbial gene expression. Marc Ongena and his team (Boubsi et al.) dissect how the pectin backbone homogalacturonan promotes bacterial differentiation programs of Bacillus velezensis, potentially facilitating its establishment in the rhizosphere.
Abstract Experimental evolution in a laboratory helps researchers to understand the genetic and phenotypic background of adaptation under a particular condition. Simultaneously, the simplified ...environment that represents certain aspects of a complex natural niche permits the dissection of relevant parameters behind the selection, including temperature, oxygen availability, nutrients, and biotic factors. The presence of other microorganisms or a host has a major influence on microbial evolution that often differs from the adaptation paths observed in response to abiotic conditions. In the current issue of the ISME Journal, Cosetta and colleagues reveal how cross-kingdom interaction representing the cheese microbiome succession promotes distinct evolution of the food- and animal-associated bacterium, Staphylococcus xylosus. The authors also identified a global regulator-dependent adaption that leads to evolved derivatives exhibiting reduced pigment production and colony morphologies in addition to altered differentiation phenotypes that potentially contribute to increased fitness.
For several decades, laboratory evolution has served as a powerful method to manipulate microorganisms and to explore long-term dynamics in microbial populations. Next to canonical Escherichia coli ...planktonic cultures, experimental evolution has expanded into alternative cultivation methods and species, opening the doors to new research questions. Bacillus subtilis, the spore-forming and root-colonizing bacterium, can easily develop in the laboratory as a liquid–air interface colonizing pellicle biofilm. Here, we summarize recent findings derived from this tractable experimental model. Clonal pellicle biofilms of B. subtilis can rapidly undergo morphological and genetic diversification creating new ecological interactions, for example, exploitation by biofilm non-producers. Moreover, long-term exposure to such matrix non-producers can modulate cooperation in biofilms, leading to different phenotypic heterogeneity pattern of matrix production with larger subpopulation of “ON” cells. Alternatively, complementary variants of biofilm non-producers, each lacking a distinct matrix component, can engage in a genetic division of labor, resulting in superior biofilm productivity compared to the “generalist” wild type. Nevertheless, inter-genetic cooperation appears to be evanescent and rapidly vanquished by individual biofilm formation strategies altering the amount or the properties of the remaining matrix component. Finally, fast-evolving mobile genetic elements can unpredictably shift intra-species interactions in B. subtilis biofilms. Understanding evolution in clonal biofilm populations will facilitate future studies in complex multispecies biofilms that are more representative of nature.
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•B. subtilis pellicle serves as a tractable and realistic model in laboratory evolution.•Biofilm diversification creates new competitive or cooperative interactions.•Division of labor in biofilms is vulnerable to evolution of individual traits.•Evolution with non-producers alters phenotypic heterogeneity of matrix expression.•Understanding complexity evolution in clonal population aids multispecies systems.
We present first evidence for the Landau level structure of Dirac eigenmodes in full QCD for nonzero background magnetic fields, based on first principles lattice simulations using staggered quarks. ...Our approach involves the identification of the lowest Landau level modes in two dimensions, where topological arguments ensure a clear separation of these modes from energetically higher states, and an expansion of the full four-dimensional modes in the basis of these two-dimensional states. We evaluate various fermionic observables including the quark condensate and the spin polarization in this basis to find how much the lowest Landau level contributes to them. The results allow for a deeper insight into the dynamics of quarks and gluons in background magnetic fields and may be directly compared to low-energy models of QCD employing the lowest Landau level approximation.
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