scholarly journals Cheaters shape the evolution of phenotypic heterogeneity in Bacillus subtilis biofilms

2018 ◽  
Author(s):  
Marivic Martin ◽  
Anna Dragoš ◽  
Simon B. Otto ◽  
Daniel Schäfer ◽  
Susanne Brix ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Prolonged Exposure ◽  
Adaptive Strategy ◽  
Phenotypic Heterogeneity ◽  
Structural Proteins ◽  
Cell Level ◽  
General Adaptation ◽  
Matrix Production ◽  
Matrix Components

ABSTRACTBiofilms are closely packed cells held and shielded by extracellular matrix composed of structural proteins and exopolysaccharides (EPS). As matrix components are costly to produce and shared within the population, EPS-deficient cells can act as cheaters by gaining benefits from the cooperative nature of EPS producers. Remarkably, genetically programmed EPS producers can also exhibit phenotypic heterogeneity at single cell level. Previous studies have shown that spatial structure of biofilms limits the spread of cheaters, but the long-term influence of cheating on biofilm evolution is not well understood. Here, we examine the influence of EPS non-producers on evolution of matrix production within the populations of EPS producers in a model biofilm-forming bacterium, Bacillus subtilis. We discovered that general adaptation to biofilm lifestyle leads to an increase in phenotypical heterogeneity of eps expression. Apparently, prolonged exposure to EPS-deficient cheaters, may result in different adaptive strategy, where eps expression increases uniformly within the population. We propose a molecular mechanism behind such adaptive strategy and demonstrate how it can benefit the EPS-producers in the presence of cheaters. This study provides additional insights on how biofilms adapt and respond to stress caused by exploitation in long-term scenario.

Surface indentation and fluid intake generated by the polymer matrix of Bacillus subtilis biofilms

Soft Matter ◽  
2015 ◽  
Vol 11 (18) ◽  
pp. 3612-3617 ◽  
Author(s):  
W. Zhang ◽  
W. Dai ◽  
Shi-Ming Tsai ◽  
S. M. Zehnder ◽  
M. Sarntinoranont ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Polymer Matrix ◽  
Fluid Intake ◽  
Elastic Stress ◽  
Force Generation ◽  
Hydraulic Permeability ◽  
Matrix Production

Bacillus subtilisbiofilm force generation is measured. The elastic stress stored in the biofilm's deformed substrate is orders of magnitude larger than the drag stress of pulling fluid into the biofilm, and depends on polymer matrix production. These results reveal that long-term biofouling and colony expansion may depend on the hydraulic permeability and elasticity of colonized surfaces.

scholarly journals Selective Proteomic Analysis of Antibiotic-Tolerant Cellular Subpopulations in Pseudomonas aeruginosa Biofilms

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Brett M. Babin ◽  
Lydia Atangcho ◽  
Mark B. van Eldijk ◽  
Michael J. Sweredoski ◽  
Annie Moradian ◽  
...  
Keyword(s):  
Proteomic Analysis ◽  
Chemical Biology ◽  
Initial Response ◽  
Adaptive Strategy ◽  
Cell Level ◽  
Cellular Physiology ◽  
Proteomic Response ◽  
Behavioral Heterogeneity ◽  
Pathogenic Biofilms

ABSTRACT Biofilm infections exhibit high tolerance against antibiotic treatment. The study of biofilms is complicated by phenotypic heterogeneity; biofilm subpopulations differ in their metabolic activities and their responses to antibiotics. Here, we describe the use of the bio-orthogonal noncanonical amino acid tagging (BONCAT) method to enable selective proteomic analysis of a Pseudomonas aeruginosa biofilm subpopulation. Through controlled expression of a mutant methionyl-tRNA synthetase, we targeted BONCAT labeling to cells in the regions of biofilm microcolonies that showed increased tolerance to antibiotics. We enriched and identified proteins synthesized by cells in these regions. Compared to the entire biofilm proteome, the labeled subpopulation was characterized by a lower abundance of ribosomal proteins and was enriched in proteins of unknown function. We performed a pulse-labeling experiment to determine the dynamic proteomic response of the tolerant subpopulation to supra-MIC treatment with the fluoroquinolone antibiotic ciprofloxacin. The adaptive response included the upregulation of proteins required for sensing and repairing DNA damage and substantial changes in the expression of enzymes involved in central carbon metabolism. We differentiated the immediate proteomic response, characterized by an increase in flagellar motility, from the long-term adaptive strategy, which included the upregulation of purine synthesis. This targeted, selective analysis of a bacterial subpopulation demonstrates how the study of proteome dynamics can enhance our understanding of biofilm heterogeneity and antibiotic tolerance. IMPORTANCE Bacterial growth is frequently characterized by behavioral heterogeneity at the single-cell level. Heterogeneity is especially evident in the physiology of biofilms, in which distinct cellular subpopulations can respond differently to stresses, including subpopulations of pathogenic biofilms that are more tolerant to antibiotics. Global proteomic analysis affords insights into cellular physiology but cannot identify proteins expressed in a particular subpopulation of interest. Here, we report a chemical biology method to selectively label, enrich, and identify proteins expressed by cells within distinct regions of biofilm microcolonies. We used this approach to study changes in protein synthesis by the subpopulation of antibiotic-tolerant cells throughout a course of treatment. We found substantial differences between the initial response and the long-term adaptive strategy that biofilm cells use to cope with antibiotic stress. The method we describe is readily applicable to investigations of bacterial heterogeneity in diverse contexts. IMPORTANCE Bacterial growth is frequently characterized by behavioral heterogeneity at the single-cell level. Heterogeneity is especially evident in the physiology of biofilms, in which distinct cellular subpopulations can respond differently to stresses, including subpopulations of pathogenic biofilms that are more tolerant to antibiotics. Global proteomic analysis affords insights into cellular physiology but cannot identify proteins expressed in a particular subpopulation of interest. Here, we report a chemical biology method to selectively label, enrich, and identify proteins expressed by cells within distinct regions of biofilm microcolonies. We used this approach to study changes in protein synthesis by the subpopulation of antibiotic-tolerant cells throughout a course of treatment. We found substantial differences between the initial response and the long-term adaptive strategy that biofilm cells use to cope with antibiotic stress. The method we describe is readily applicable to investigations of bacterial heterogeneity in diverse contexts.

scholarly journals Impact of Prolonged Exposure of Eleven Years to Hot Seawater on the Degradation of a Thermoset Composite

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2154
Author(s):  
Amir Hussain Idrisi ◽  
Abdel-Hamid I. Mourad ◽  
Muhammad M. Sherif
Keyword(s):  
Exposure Time ◽  
Prolonged Exposure ◽  
Mechanical Performance ◽  
Matrix Cracking ◽  
Pull Out ◽  
Strength Based ◽  
Different Temperatures ◽  
River Line ◽  
Composite Samples

This paper presents a long-term experimental investigation of E-glass/epoxy composites’ durability exposed to seawater at different temperatures. The thermoset composite samples were exposed to 23 °C, 45 °C and 65 °C seawater for a prolonged exposure time of 11 years. The mechanical performance as a function of exposure time was evaluated and a strength-based technique was used to assess the durability of the composites. The experimental results revealed that the tensile strength of E-glass/epoxy composite was reduced by 8.2%, 29.7%, and 54.4% after immersion in seawater for 11 years at 23 °C, 45 °C, and 65 °C, respectively. The prolonged immersion in seawater resulted in the plasticization and swelling in the composite. This accelerated the rate of debonding between the fibers and matrix. The failure analysis was conducted to investigate the failure mode of the samples. SEM micrographs illustrated a correlation between the fiber/matrix debonding, potholing, fiber pull-out, river line marks and matrix cracking with deterioration in the tensile characteristics of the thermoset composite.

scholarly journals Onset and Resolution of Key Adverse Events in Valbenazine-Treated Patients with Tardive Dyskinesia: Pooled Analyses from Two Long-Term Clinical Trials

CNS Spectrums ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 151-151
Author(s):  
Stephen R. Marder ◽  
Jean-Pierre Lindenmayer ◽  
Chirag Shah ◽  
Tara Carmack ◽  
Angel S. Angelov ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Adverse Events ◽  
Tardive Dyskinesia ◽  
Suicidal Behavior ◽  
Prolonged Exposure ◽  
First Occurrence ◽  
Balance Disorder ◽  
Clinical Interest ◽  
Post Hoc

AbstractObjectiveTardive dyskinesia (TD) is a persistent and potentially disabling movement disorder associated with prolonged exposure to antipsychotics and other dopamine receptor blocking agents. Long-term safety of the approved TD medication, valbenazine, was demonstrated in 2 clinical trials (KINECT 3 [NCT02274558], KINECT 4 [NCT02405091]). Data from these trials were analyzed post hoc to evaluate the onset and resolution of adverse events (AEs).MethodsParticipants in KINECT 3 and KINECT 4 received up to 48 weeks of once-daily valbenazine (40 or 80 mg). Data from these studies were pooled and analyzed to assess the incidence, time to first occurrence, and resolution for the following AEs of potential clinical interest: akathisia, balance disorder, dizziness, parkinsonism, somnolence/sedation, suicidal behavior/ideation, and tremor.ResultsIn the pooled population (N=314), all AEs of potential clinical interest occurred in <10% of participants, with somnolence (9.6%), suicidal behavior/ideation (6.4%), and dizziness (5.7%) being the most common AEs. Mean time to first occurrence ranged from 36 days (akathisia [n=9]) to 224 days (parkinsonism [n=2]). By end of study (or last study visit), resolution of AEs was as follows: 100% (suicidal ideation/behavior, parkinsonism); >85% (somnolence/sedation, dizziness); >70% (akathisia, balance disorder, tremor).ConclusionsIn long-term clinical trials, the incidence of AEs of potential clinical interest was low (<10%) and most were resolved by end of treatment (>70–100%). All patients taking valbenazine should be routinely monitored for AEs, particularly those that may exacerbate the motor symptoms associated with TD.FundingNeurocrine Biosciences, Inc.

scholarly journals The phosphoproteome of rice leaves responds to water and nitrogen supply

2021 ◽  
Author(s):  
Sara Hamzelou ◽  
Vanessa J. Melino ◽  
Darren C. Plett ◽  
Karthik Shantharam Kamath ◽  
Arkadiusz Nawrocki ◽  
...  
Keyword(s):  
Prolonged Exposure ◽  
Water Channel ◽  
Nitrogen Supply ◽  
Nitrogen Fertilizers ◽  
Label Free ◽  
Limited Information ◽  
Irrigated Rice ◽  
Post Translational Modifications ◽  
Growth Adaptation

The scarcity of freshwater is an increasing concern in flood-irrigated rice, whilst excessive use of nitrogen fertilizers is both costly and contributes to environmental pollution. To co-ordinate growth adaptation under prolonged exposure to limited water or excess nitrogen supply, plants have processes for signalling and regulation of metabolic processes. There is limited information on the involvement of one of the most important post-translational modifications (PTMs), protein phosphorylation, on plant adaptation to long-term changes in resource supply. Oryza sativa cv. Nipponbare was grown under two regimes of nitrogen from the time of germination to final harvest. Twenty-five days after germination, water was withheld from half the pots in each nitrogen treatment and low water supply continued for an additional 26 days, while the remaining pots were well watered. Leaves from all four groups of plants were harvested after 51 days in order to test whether phosphorylation of leaf proteins responded to prior abiotic events. The dominant impact of these resources is exerted in leaves, where PTMs have been predicted to occur. Proteins were extracted and phosphopeptides were analysed by nanoLC-MS/MS analysis, coupled with label-free quantitation. Water and nitrogen regimes triggered extensive changes in phosphorylation of proteins involved in membrane transport, such as the aquaporin OsPIP2-6, a water channel protein. Our study reveals phosphorylation of several peptides belonging to proteins involved in RNA-processing and carbohydrate metabolism, suggesting that phosphorylation events regulate the signalling cascades that are required to optimize plant response to resource supply.

scholarly journals Degradation of chlorobenzene and 2-chlorotoluene by immobilized bacteria strains Comamonas testosterone kt5 and Bacillus subtilis dkt

2019 ◽  
Vol 41 (4) ◽  
Author(s):  
Ha Danh Duc ◽  
Nguyen Thi Oanh
Keyword(s):  
Bacillus Subtilis ◽  
Bacterial Strain ◽  
Immobilized Cells ◽  
Resting Cells ◽  
Long Term Storage ◽  
Degradation Rates ◽  
Contributory Negligence ◽  
Biofilm Bacteria ◽  
Term Storage

Chlorobenzenes and chlorotoluenes have been used to produce a number of industrial products. They are toxic and widely detected in environments due to human contributory negligence. In this article, the mixed culture of a toluenes-degrading bacterial strain, Comamonas testosterone KT5 (a Gram-positive, catalase-positive bacterium) and a chlorobenzenes-degrading bacterial strain, Bacillus subtilis DKT (a Gram-negative soil bacterium) effectively degraded both chemical compounds co-contaminating in liquid media. In addition, the degradations of mixed compounds by biofilm, bacteria immobilized in polyurethane foam (PUF) and alginate were determined. The results showed that the degradation of both compounds by cells in alginate was significantly higher than that by suspended cells. Moreover, cells immobilized in these materials showed lower adverse effects than those of non-immobilized cells for long-term storage. For examples, the degradation rates for chlorobenzine and 2-chlorotoluene by resting cells reduced by 39.5% and 37.3% after storage for 4 months at 4°C, while the degradation rates by immobilized cells decreased by from 16.3% to 19.8% respectively. 

Bioconvective dynamics: dependence on organism behaviour

2000 ◽  
Vol 203 (21) ◽  
pp. 3345-3354 ◽  
Author(s):  
A. Czirok ◽  
I.M. Janosi ◽  
J.O. Kessler
Keyword(s):  
Bacillus Subtilis ◽  
Cell Density ◽  
Microbial Populations ◽  
Dominant Wavelength ◽  
Nonlinear Convection ◽  
Convection Regime ◽  
Term Evolution ◽  
Convection Patterns ◽  
Micro Organisms

Bioconvection occurs when a macroscopic nonuniformity of the concentration of microbial populations is generated and maintained by the directional swimming of the organisms. This study investigated the properties of the patterns near the onset of the instability and later during its evolution into a fully nonlinear convection regime. In suspensions of the bacteria Bacillus subtilis, which tend to swim upwards in a gradient of oxygen concentration that they create by consumption, we discovered that the dominant wavelength at the onset of the instability is determined primarily by the cell density and is influenced only weakly by the fluid depth. This observation contrasts strongly with previous observations on the gravitactic alga Chlamydomonas nivalis, in which the opposite dependence was found. Considerable differences were also found in the long-term evolution of the convection patterns. These results demonstrate the existence of readily distinguishable types of bioconvection systems, even at early stages of the instability. The observed differences are clearly and causally correlated with disparate reasons for upward swimming by these micro-organisms, leading to different geometric distributions of the density of the suspension.

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