scholarly journals Cooperation and spatial self-organization determine ecosystem function for polysaccharide-degrading bacteria

2019 ◽  
Author(s):  
Ali Ebrahimi ◽  
Julia Schwartzman ◽  
Otto X. Cordero
Keyword(s):  
Public Goods ◽  
Social Interactions ◽  
Ecosystem Function ◽  
High Efficiency ◽  
Particle Surface ◽  
Microbial Interactions ◽  
Self Organization ◽  
Ecosystem Functions ◽  
Degrading Bacteria ◽  
The Impact

AbstractThe recycling of particulate organic matter (POM) by microbes is a key part of the global carbon cycle, one which is mediated by the extracellular hydrolysis of polysaccharides and the production of public goods that can trigger social behaviors in bacteria. Despite the potential importance of these microbial interactions, their role in regulating of ecosystem function remains unclear. In this study, we developed a computational and experimental model system to address this challenge and studied how POM depolymerization rate and its uptake efficiency –two main ecosystem function parameters– depended on social interactions and spatial self-organization on particle surfaces. We found an emergent trade-off between rate and efficiency resulting from the competition between oligosaccharide diffusion and cellular uptake, with low rate and high efficiency being achieved through cell-to-cell cooperation between degraders. Bacteria cooperated by aggregating in cell-clusters of ~10-20μm, where cells were able to share public goods. This phenomenon, which was independent of any explicit group-level regulation, led to the emergence of critical cell concentrations below which degradation did not occur, despite all resources being available in excess. By contrast, when particles were labile and turnover rates were high, aggregation promoted competition and decreased the efficiency of carbon utilization. Our study shows how social interactions and cell aggregation determine the rate and efficiency of particulate carbon turnover in environmentally relevant scenarios.Significance StatementMicroorganisms can cooperate by secreting public goods that benefit local neighbors, however, the impact of cooperation on ecosystem functions remains poorly constrained. We here pair computation and experiment to show that bacterial cooperation mediates the degradation of polysaccharide particles recalcitrant to hydrolysis in aquatic environments. On particle surfaces, cooperation emerges through the self-organization of cells into ~10-20μm clusters that promote cooperative uptake of hydrolysis products. The transition between cooperation and competition in aggregates is mitigated by individual cell behaviors such as motility and chemotaxis, that promote reorganization on the particle surface. When cooperation is required, the degradation of recalcitrant biopolymers can only take place when degraders exceed a critical cell concentration, underscoring the importance of microbial interactions for ecosystem function.

scholarly journals Cooperation and spatial self-organization determine rate and efficiency of particulate organic matter degradation in marine bacteria

2019 ◽  
Vol 116 (46) ◽  
pp. 23309-23316 ◽  
Author(s):  
Ali Ebrahimi ◽  
Julia Schwartzman ◽  
Otto X. Cordero
Keyword(s):  
Organic Matter ◽  
Public Goods ◽  
Social Interactions ◽  
Particulate Organic Matter ◽  
High Efficiency ◽  
Cell Aggregation ◽  
Self Organization ◽  
Turnover Rates ◽  
Particulate Carbon ◽  
Hydrolysis Of

The recycling of particulate organic matter (POM) by microbes is a key part of the global carbon cycle. This process is mediated by the extracellular hydrolysis of polysaccharides, which can trigger social behaviors in bacteria resulting from the production of public goods. Despite the potential importance of public good-mediated interactions, their relevance in the environment remains unclear. In this study, we developed a computational and experimental model system to address this challenge and studied how the POM depolymerization rate and its uptake efficiency (2 main ecosystem function parameters) depended on social interactions and spatial self-organization on particle surfaces. We found an emergent trade-off between rate and efficiency resulting from the competition between oligosaccharide diffusion and cellular uptake, with low rate and high efficiency being achieved through cell-to-cell cooperation between degraders. Bacteria cooperated by aggregating in cell clusters of ∼10 to 20 µm, in which cells were able to share public goods. This phenomenon, which was independent of any explicit group-level regulation, led to the emergence of critical cell concentrations below which degradation did not occur, despite all resources being available in excess. In contrast, when particles were labile and turnover rates were high, aggregation promoted competition and decreased the efficiency of carbon use. Our study shows how social interactions and cell aggregation determine the rate and efficiency of particulate carbon turnover in environmentally relevant scenarios.

scholarly journals Frequency of disturbance alters diversity, function, and underlying assembly mechanisms of complex bacterial communities

2018 ◽  
Author(s):  
Ezequiel Santillan ◽  
Hari Seshan ◽  
Florentin Constancias ◽  
Daniela I. Drautz-Moses ◽  
Stefan Wuertz
Keyword(s):  
Microbial Communities ◽  
Ecosystem Function ◽  
Null Model ◽  
Biomass Productivity ◽  
Community Diversity ◽  
Ecosystem Functions ◽  
Rrna Gene ◽  
Ecosystem Structure ◽  
Stochastic Assembly ◽  
The Impact

AbstractDisturbance is known to affect ecosystem structure, but predicting its outcomes remains elusive. Similarly, community diversity is believed to relate to ecosystem functions, yet the underlying mechanisms are poorly understood. Here, we tested the effect of disturbance on the structure, diversity, and ecosystem function of complex microbial communities within an engineered system. We carried out a microcosm experiment where activated sludge bioreactors were subjected to a range of disturbances in the form of a toxic pollutant, tracking changes in ecosystem function. Microbial communities were assessed by combining distance-based methods, general linear multivariate models, α-diversity indices, and null model analyses on metagenomics and 16S rRNA gene amplicon data. A stronger temporal decrease in α-diversity at the extreme, undisturbed and press-disturbed, ends of the disturbance range led to a hump-backed pattern, with the highest diversity found at intermediate levels of disturbance. Undisturbed and press-disturbed levels displayed the highest community and functional similarity across replicates, suggesting deterministic processes were dominating. The opposite was observed amongst intermediately disturbed levels, indicating stronger stochastic assembly mechanisms. Tradeoffs were observed in community function between organic carbon removal and both nitrification and biomass productivity, as well as between diversity and these functions. Hence, not every ecosystem function was favoured by higher community diversity. Our results show that the assessment of changes in diversity, along with the underlying stochastic-niche assembly processes, is essential to understanding the impact of disturbance in complex microbial communities.ImportanceMicrobes drive the Earth’s biogeochemical cycles, yet how they respond to perturbations like anthropogenic pollutants is poorly understood. As human impact continues to increase worldwide, foreseeing how disturbances will affect microbial communities and the ecosystem services they provide is key for ecosystem management and conservation efforts. Employing laboratory-scale wastewater treatment bioreactors, this study shows that changes in community diversity accompany variations in the underlying deterministic-stochastic assembly mechanisms. Disturbances could promote stochastic community structuring, which despite harboring higher diversity could lead to variable overall function, possibly explaining why after similar perturbations the process outcome differs. A conceptual framework, termed the ‘intermediate stochasticity hypothesis’ is proposed to theoretically predict bacterial community shifts in diversity and ecosystem function, given a range of possible disturbance types, in a well-replicated time-series experiment. Our findings are relevant for managing complex microbial systems, which could display similar responses to disturbance, like oceans, soils or the human gut.

Piezoelectric β-polymorph formation of new textiles by surface modification with coating process based on interfacial interaction on the conformational variation of poly (vinylidene fluoride) (PVDF) chains

2020 ◽  
Vol 91 (3) ◽  
pp. 31301
Author(s):  
Nabil Chakhchaoui ◽  
Rida Farhan ◽  
Meriem Boutaldat ◽  
Marwane Rouway ◽  
Adil Eddiai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Vinylidene Fluoride ◽  
Research Work ◽  
Research Area ◽  
Interfacial Interaction ◽  
Tetraethyl Orthosilicate ◽  
Poly Vinylidene Fluoride ◽  
Carbon Nanofillers ◽  
The Impact ◽  
Advanced Applications

Novel textiles have received a lot of attention from researchers in the last decade due to some of their unique features. The introduction of intelligent materials into textile structures offers an opportunity to develop multifunctional textiles, such as sensing, reacting, conducting electricity and performing energy conversion operations. In this research work nanocomposite-based highly piezoelectric and electroactive β-phase new textile has been developed using the pad-dry-cure method. The deposition of poly (vinylidene fluoride) (PVDF) − carbon nanofillers (CNF) − tetraethyl orthosilicate (TEOS), Si(OCH2CH3)4 was acquired on a treated textile substrate using coating technique followed by evaporation to transform the passive (non-functional) textile into a dynamic textile with an enhanced piezoelectric β-phase. The aim of the study is the investigation of the impact the coating of textile via piezoelectric nanocomposites based PVDF-CNF (by optimizing piezoelectric crystalline phase). The chemical composition of CT/PVDF-CNC-TEOS textile was detected by qualitative elemental analysis (SEM/EDX). The added of 0.5% of CNF during the process provides material textiles with a piezoelectric β-phase of up to 50% has been measured by FTIR experiments. These results indicated that CNF has high efficiency in transforming the phase α introduced in the unloaded PVDF, to the β-phase in the case of nanocomposites. Consequently, this fabricated new textile exhibits glorious piezoelectric β-phase even with relatively low coating content of PVDF-CNF-TEOS. The study demonstrates that the pad-dry-cure method can potentially be used for the development of piezoelectric nanocomposite-coated wearable new textiles for sensors and energy harvesting applications. We believe that our study may inspire the research area for future advanced applications.

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

The Impact of a Chemostat Discharge Containing Oil Degrading Bacteria on the Biological Kinetics of a Refinery Activated Sludge Process

1988 ◽  
Vol 20 (11-12) ◽  
pp. 131-136 ◽  
Author(s):  
A. D. Wong ◽  
C. D. Goldsmith
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Waste Treatment ◽  
Treatment Plant ◽  
Utilization Rate ◽  
Activated Sludge Process ◽  
Kinetic Evaluation ◽  
Degrading Bacteria ◽  
Waste Treatment Plant ◽  
The Impact

The effect of discharging specific oil degrading bacteria from a chemostat to a refinery activated sludge process was determined biokinetically. Plant data for the kinetic evaluation of the waste treatment plant was collected before and during treatment. During treatment, the 500 gallon chemostatic growth chamber was operated on an eight hour hydraulic retention time, at a neutral pH, and was fed a mixture of refinery wastewater and simple sugars. The biokinetic constants k (days−1), Ks (mg/L), and K (L/mg-day) were determined before and after treatment by Monod and Lineweaver-Burk plots. Solids discharged and effluent organic concentrations were also evaluated against the mean cell retention time (MCRT). The maximum utilization rate, k, was found to increase from 0.47 to 0.95 days−1 during the operation of the chemostat. Subsequently, Ks increased from 141 to 556 mg/L. Effluent solids were shown to increase slightly with treatment. However, this was acceptable due to the polishing pond and the benefit of increased ability to accept shock loads of oily wastewater. The reason for the increased suspended solids in the effluent was most likely due to the continual addition of bacteria in exponential growth that were capable of responding to excess substrate. The effect of the chemostatic addition of specific microbial inocula to the refinery waste treatment plant has been to improve the overall organic removal capacity along with subsequent gains in plant stability.

scholarly journals POS0329 GASTROINTESTINAL INVOLVEMENT IN SYSTEMIC SCLEROSIS: PATHOGENETIC ROLE OF GUT MICROBIOME, CYTOKINES AND ADIPOKINES

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 392.1-392
Author(s):  
E. Pigatto ◽  
M. Schiesaro ◽  
M. Caputo ◽  
M. Beggio ◽  
P. Galozzi ◽  
...  
Keyword(s):  
Systemic Sclerosis ◽  
Gut Microbiome ◽  
Serum Levels ◽  
High Serum ◽  
Healthy Population ◽  
Gastrointestinal Involvement ◽  
Degrading Bacteria ◽  
Gi Symptoms ◽  
Low Levels ◽  
The Impact

Background:Gastrointestinal (GI) involvement is very common in patients with Systemic Sclerosis (SSc). The pathophysiology of GI manifestations has not yet been defined. Cell-mediated immunological reactions appear to lead to endothelial damage resulting in fibrosis. The risk of developing malnutrition reinforces the need to better understand GI pathophysiology in these patients.Objectives:The study aimed to evaluate GI symptoms (GIT 2.0) and malnutrition status (MUST) and to determine specific bacterial changes in gut microbiome by investigating the possible presence of positive hot spots in bacterial species in SSc patients and their potential role in the disease progression. We also evaluated serum levels of adipokines and cytokines involved in the pathogenesis of SSc and their role, in addition to gut microbiome, in predicting the onset of GI involvement and malnutrition in SSc patients.Methods:We enrolled 25 scleroderma patients (EULAR/ACR 2013 criteria). UCLA-SCTC GIT 2.0 questionnaire to evaluate GI symptoms and MUST to investigate the risk of malnutrition were used. Gut microbiome was analyzed and the samples were subjected to extraction for the 16S rRNA gene (Earth Microbiome Project and the NIH-Human Microbiome Project). The microbiome was investigated at phenotypic and genotypic level. Serum levels of cytokines and adipokines (adiponectin and leptin) were evaluated by ELISA.Results:79.9% of patients had GERD and 63.5% abdominal distension at GIT 2.0 questionnaires. 48% of patients had moderate risk of malnutrition (MUST=2) and 12% had high risk (MUST=3). Gut microbioma: 19 patients (76%) had low similarity and 11 (44%) low diversity compared to the healthy population. The prevailing enterotypes of gut microbiome was Bacteroides (80%) and Prevotella (20%). The genotypic evaluation showed a reduced concentration of: gluten-digesting (Lactobacillus); lactose-digesting (Faecalibacterium); vitamin K-producing (Enterococcus, Desulfovibrio and Veillonella); acetaldehyde-degrading bacteria. 24 patients (96%) showed a reduction in bacteria devoted to maintaining weight control (Bifidobacterium and Ruminococcus). The patients had an altered intestinal permeability with less mucolytic bacteria (Bacteroides) and reduced production of LPS (Enterobacter and Escherichia). Low levels of butyrate (Eubacterium and Clostridium), acetate and propionate were found for SCFA-producing bacteria. Potentially pathogenic bacteria were also investigated: Salmonella was found in 14 (56%), Klebsiella in 9 (36%) and Enterococcus Faecalis in 3 (12%) patients. 11 (44%) patients had elevated serum levels of IL10 and IL12; 4 (16%) had high value of leptin. Correlation was found in patients who had a reduced concentration of gluten-digesting bacteria and MUST. Elevated MUST was correlated with serological increase in IL17A and IFN-α. Serum levels of IL12 and IL10 were found to correlate with specific bacteria alterations: high concentration of acetaldehyde-producing bacteria and low levels of acetaldehyde-degrade bacteria (also correlated with high serum levels of IL6), mucolytic bacteria and producers of hydrogen sulphide, acetate and propionate. Finally, reduced levels of mucolytic bacteria and acetate producing bacteria correlated with high serum leptin levels.Conclusion:The relationship between the gut microbiome and SSc seems to be multifactorial. In our study genotypic changes of gut microbioma might play a role in damaging the permeability of the mucosa and increasing risk of malnutrition. The evaluation of gut microbiome and cytokine profile is probably going to be of value in the follow-up of SSc. However, further studies are needed to clarify the impact of GI dysbiosis on the immune system in SSc.References:[1]Patrone V. et al. Gut microbiota profile in systemic sclerosis patients with and without clinical evidence of gastrointestinal involvement, Sci Rep. 2017; 7: 14874Disclosure of Interests:None declared

scholarly journals Theoretical Studies of the Interaction between Screw Surface and Material in the Mixer

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 962
Author(s):  
Andrzej Marczuk ◽  
Vasily Sysuev ◽  
Alexey Aleshkin ◽  
Petr Savinykh ◽  
Nikolay Turubanov ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
High Efficiency ◽  
Animal Feed ◽  
Structural Features ◽  
Power Demand ◽  
Friction Coefficients ◽  
Length Unit ◽  
Mixing Chamber ◽  
Size Of Particles ◽  
The Impact

Mixing is one of the most commonly used processes in food, animal feed, chemical, cosmetic, etc., industries. It is supposed to provide high-quality homogenous, nutritious mixtures. To provide appropriate mixing of materials while maintaining the process high efficiency and low energy consumption it is crucial to explore and describe the material flow caused by the movement of mixing elements and the contact between particles. The process of mixing is also affected by structural features of the machine components and the mixing chamber, speed of mixing, and properties of the mixed materials, such as the size of particles, moisture, friction coefficients. Thus, modeling of the phenomena that accompany the process of mixing using the above-listed parameters is indispensable for appropriate implementation of the process. The paper provides theoretical power calculations that take into account the material speed change, the impact of the material friction coefficient on the screw steel surface and the impact of the friction coefficient on the material, taking into account the loading height of the mixing chamber and the chamber loading value. Dependencies between the mixer power and the product degree of fineness, rotational speed of screw friction coefficients, the number of windings per length unit, and width of the screw tape have been presented on the basis of a developed model. It has been found that power increases along with an increase in the value of these parameters. Verification of the theoretical model indicated consistence of the predicted power demand with the power demand determined in tests performed on a real object for values of the assumed, effective loading, which was 65–75%.

scholarly journals COVID-19 Pandemic Turns Life-Science Students into “Citizen Scientists”: Data Indicate Multiple Negative Effects of Urbanization on Biota

2021 ◽  
Vol 13 (5) ◽  
pp. 2992
Author(s):  
Jens Schirmel
Keyword(s):  
Citizen Science ◽  
Online Teaching ◽  
Teaching Strategy ◽  
Ecosystem Functions ◽  
Negative Effects ◽  
Ecological Data ◽  
Pollinating Insects ◽  
Impact Of Urbanization ◽  
Data Collections ◽  
The Impact

The COVID-19 pandemic and its restrictions strongly affect the higher education community and require diverse teaching strategies. We designed a course where we combined online teaching with independently conducted ecological data collections by students using a “citizen science” approach. The aim was to analyze the impact of urbanization on biota by comparing urban and rural grasslands. Seventy-five students successfully conducted the data collections and the results provide evidence for prevailing negative effects of urbanization. Individual numbers of ground-dwelling invertebrates (−25%) and pollinating insects (−33%) were generally lower in urban sites. Moreover, animal and seed predation were reduced in urban grasslands, indicating the potential of urbanization to alter ecosystem functions. Despite the general limitations of online teaching and citizen science approaches, outcomes of this course showed this combination can be a useful teaching strategy, which is why this approach could be used to more actively involve students in scientific research.

scholarly journals Nonlocal and Size-Dependent Dielectric Function for Plasmonic Nanoparticles

2019 ◽  
Vol 9 (15) ◽  
pp. 3083
Author(s):  
Kai-Jian Huang ◽  
Shui-Jie Qin ◽  
Zheng-Ping Zhang ◽  
Zhao Ding ◽  
Zhong-Chen Bai
Keyword(s):  
Metallic Nanoparticles ◽  
High Efficiency ◽  
Finite Size ◽  
Plasmonic Nanostructures ◽  
Accurate Analysis ◽  
Finite Size Effects ◽  
Size Dependent ◽  
Quantum Size ◽  
The Impact ◽  
Electron Energy Loss

We develop a theoretical approach to investigate the impact that nonlocal and finite-size effects have on the dielectric response of plasmonic nanostructures. Through simulations, comprehensive comparisons of the electron energy loss spectroscopy (EELS) and the optical performance are discussed for a gold spherical dimer system in terms of different dielectric models. Our study offers a paradigm of high efficiency compatible dielectric theoretical framework for accounting the metallic nanoparticles behavior combining local, nonlocal and size-dependent effects in broader energy and size ranges. The results of accurate analysis and simulation for these effects unveil the weight and the evolution of both surface and bulk plasmons vibrational mechanisms, which are important for further understanding the electrodynamics properties of structures at the nanoscale. Particularly, our method can be extended to other plasmonic nanostructures where quantum-size or strongly interacting effects are likely to play an important role.

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