Community structure of micro- and macroflocs in pin-point sludge and the influence of sludge age and potassium addition on microfloc formation

2002 ◽  
Vol 46 (1-2) ◽  
pp. 405-412 ◽  
Author(s):  
E. Müller ◽  
K. Kriebitzsch ◽  
P.A. Wilderer ◽  
S. Wuertz
Keyword(s):  
Community Structure ◽  
Microbial Communities ◽  
Extracellular Polymeric Substances ◽  
Point Of View ◽  
Sludge Formation ◽  
Industrial Plants ◽  
Noticeable Improvement ◽  
Lower Protein ◽  
Utilization Patterns ◽  
The Impact

Settling problems caused by pin-point sludge constitute a serious problem in biological wastewater treatment, particularly in many industrial plants. Until now, most studies focused on the relationship between pin-point sludge formation and either shearing forces or the impact of toxicants. This study deals with the community structure in both the micro- and macrofloc fraction which was analyzed by fluorescent in situ hybridization (FISH) and BIOLOG substrate utilization patterns. It was shown that each fraction consisted of different microbial communities with unique metabolic profiles suggesting that pin-point sludge formation is not due to dispersal of intact flocs but to microcolonies growing separately. Alternatively, macroflocs may have an architecture leading to segregation of microbial communities after floc dispersal. Further it could be shown that the formation of microflocs was influenced by sludge age. The best sludge sedimentation was obtained for a sludge age of 5 and 10 days. Additional analysis of extracellular polymeric substances (EPS) suggested that the lower protein to carbohydrate ratio of 10-day-old sludge led to better flocculation compared to 20-day-old sludge containing similar total amounts of EPS. From a practical point of view, addition of potassium (0.1 g/l) effected a noticeable improvement of sludge settleability.

scholarly journals Spatio-temporal modeling of the crowding conditions and metabolic variability in microbial communities

2021 ◽  
Vol 17 (7) ◽  
pp. e1009140
Author(s):  
Liliana Angeles-Martinez ◽  
Vassily Hatzimanikatis
Keyword(s):  
Microbial Communities ◽  
Extracellular Polymeric Substances ◽  
Resource Competition ◽  
Local Environment ◽  
Microbial Interactions ◽  
Relative Fitness ◽  
Flux Analysis ◽  
Scaled Particle Theory ◽  
Spatio Temporal ◽  
The Impact

The metabolic capabilities of the species and the local environment shape the microbial interactions in a community either through the exchange of metabolic products or the competition for the resources. Cells are often arranged in close proximity to each other, creating a crowded environment that unevenly reduce the diffusion of nutrients. Herein, we investigated how the crowding conditions and metabolic variability among cells shape the dynamics of microbial communities. For this, we developed CROMICS, a spatio-temporal framework that combines techniques such as individual-based modeling, scaled particle theory, and thermodynamic flux analysis to explicitly incorporate the cell metabolism and the impact of the presence of macromolecular components on the nutrients diffusion. This framework was used to study two archetypical microbial communities (i) Escherichia coli and Salmonella enterica that cooperate with each other by exchanging metabolites, and (ii) two E. coli with different production level of extracellular polymeric substances (EPS) that compete for the same nutrients. In the mutualistic community, our results demonstrate that crowding enhanced the fitness of cooperative mutants by reducing the leakage of metabolites from the region where they are produced, avoiding the resource competition with non-cooperative cells. Moreover, we also show that E. coli EPS-secreting mutants won the competition against the non-secreting cells by creating less dense structures (i.e. increasing the spacing among the cells) that allow mutants to expand and reach regions closer to the nutrient supply point. A modest enhancement of the relative fitness of EPS-secreting cells over the non-secreting ones were found when the crowding effect was taken into account in the simulations. The emergence of cell-cell interactions and the intracellular conflicts arising from the trade-off between growth and the secretion of metabolites or EPS could provide a local competitive advantage to one species, either by supplying more cross-feeding metabolites or by creating a less dense neighborhood.

scholarly journals Depth and location influence prokaryotic and eukaryotic microbial community structure in New Zealand fjords

2019 ◽  
Author(s):  
Sven P. Tobias-Hünefeldt ◽  
Stephen R. Wing ◽  
Nadjejda Espinel-Velasco ◽  
Federico Baltar ◽  
Sergio E. Morales
Keyword(s):  
Community Structure ◽  
New Zealand ◽  
Microbial Communities ◽  
National Park ◽  
Amplicon Sequencing ◽  
Forested Catchments ◽  
Environmental Forcing ◽  
Low Salinity ◽  
The Impact ◽  
Depth View

SummarySystems with strong horizontal and vertical gradients, such as fjords, are useful models for studying environmental forcing. Here we examine microbial (prokaryotic and eukaryotic) community changes associated with the surface low salinity layer (LSL) and underlying seawater in multiple fjords in Fiordland National Park (New Zealand). High rainfall (1200-8000 mm annually) and linked runoff from native forested catchments results in surface LSLs with high tannin concentrations within each fjord. These gradients are expected to drive changes in microbial communities. We used amplicon sequencing (16S and 18S) to assess the impact of these gradients on microbial communities and identified depth linked changes in diversity and community structure. With increasing depth we observed significant increases in Proteobacteria (15%) and SAR (37%), decreases in Opisthokonta (35%), and transiently increased Bacteroidetes (3% increase from 0 to 40 m, decreasing by 8% at 200 m). Community structure differences were observed along a transect from inner to outer regions, specifically 25% mean relative abundance decreases in Opisthokonta and Bacteroidetes, and increases in SAR (25%) and Proteobacteria (>5%) at the surface, indicating changes based on distance from the ocean. This provides the first in-depth view into the ecological drivers of microbial communities within New Zealand fjords.

Assessment of drinking water filter microbial communities using taxonomic and metabolic profiles

1999 ◽  
Vol 39 (7) ◽  
pp. 83-89 ◽  
Author(s):  
Deborah M. Moll ◽  
R. Scott Summers
Keyword(s):  
Drinking Water ◽  
Community Structure ◽  
Microbial Communities ◽  
Contact Time ◽  
Phospholipid Fatty Acid ◽  
Drinking Water Treatment ◽  
Disinfection Byproducts ◽  
Biologically Active ◽  
Biolog System ◽  
The Impact

Biofiltration is used in drinking water treatment to oxidize the biodegradable fraction of natural organic matter (NOM), thus controlling disinfection byproducts (DBP), DBP formation and microbial regrowth. Most work to date has focused on assessing drinking water biofilter performance; the microbial dynamics of biofilters have not been examined and are poorly understood. The objective of this research was to provide baseline information about the impact of design, operational and water quality parameters on NOM and DBP precursor removal, and microbial biomass and community structure profiles of biologically active drinking water rapid media filters. Phospholipid fatty acid (PLFA) profiles and the BIOLOG system for detecting the metabolism of sole carbon sources were found to be useful for characterizing the microbial communities in drinking water biofilters. Substrate removal was impacted most by ozonation, contact time, backwashing with water containing disinfectants, and low temperature. Using the PLFA technique, it was found that ozonation, contact time, and backwashing with water containing disinfectants had the greatest impact on microbial community structure. The BIOLOG system differentiated communities based on ozonation, contact time, pH, and temperature.

scholarly journals Rhizosphere Microbial Community Structure in Relation to Root Location and Plant Iron Nutritional Status

2000 ◽  
Vol 66 (1) ◽  
pp. 345-351 ◽  
Author(s):  
Ching-Hong Yang ◽  
David E. Crowley
Keyword(s):  
Community Structure ◽  
Nutritional Status ◽  
Microbial Communities ◽  
16S Rdna ◽  
Bacterial Communities ◽  
Root Exudate ◽  
Primary Root ◽  
Root Tips ◽  
Root Zones ◽  
The Impact

ABSTRACT Root exudate composition and quantity vary in relation to plant nutritional status, but the impact of the differences on rhizosphere microbial communities is not known. To examine this question, we performed an experiment with barley (Hordeum vulgare) plants under iron-limiting and iron-sufficient growth conditions. Plants were grown in an iron-limiting soil in root box microcosms. One-half of the plants were treated with foliar iron every day to inhibit phytosiderophore production and to alter root exudate composition. After 30 days, the bacterial communities associated with different root zones, including the primary root tips, nonelongating secondary root tips, sites of lateral root emergence, and older roots distal from the tip, were characterized by using 16S ribosomal DNA (rDNA) fingerprints generated by PCR-denaturing gradient gel electrophoresis (DGGE). Our results showed that the microbial communities associated with the different root locations produced many common 16S rDNA bands but that the communities could be distinguished by using correspondence analysis. Approximately 40% of the variation between communities could be attributed to plant iron nutritional status. A sequence analysis of clones generated from a single 16S rDNA band obtained at all of the root locations revealed that there were taxonomically different species in the same band, suggesting that the resolving power of DGGE for characterization of community structure at the species level is limited. Our results suggest that the bacterial communities in the rhizosphere are substantially different in different root zones and that a rhizosphere community may be altered by changes in root exudate composition caused by changes in plant iron nutritional status.

scholarly journals Corexit 9500 Enhances Oil Biodegradation and Changes Active Bacterial Community Structure of Oil-Enriched Microcosms

2017 ◽  
Vol 83 (10) ◽  
Author(s):  
Stephen M. Techtmann ◽  
Mobing Zhuang ◽  
Pablo Campo ◽  
Edith Holder ◽  
Michael Elk ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Microbial Communities ◽  
Bacterial Community Structure ◽  
Oil Spills ◽  
Content Type ◽  
Corexit 9500 ◽  
Oil Biodegradation ◽  
Degrading Bacteria ◽  
The Impact

ABSTRACT To better understand the impacts of Corexit 9500 on the structure and activity levels of hydrocarbon-degrading microbial communities, we analyzed next-generation 16S rRNA gene sequencing libraries of hydrocarbon enrichments grown at 5 and 25°C using both DNA and RNA extracts as the sequencing templates. Oil biodegradation patterns in both 5 and 25°C enrichments were consistent with those reported in the literature (i.e., aliphatics were degraded faster than aromatics). Slight increases in biodegradation were observed in the presence of Corexit at both temperatures. Differences in community structure were observed between treatment conditions in the DNA-based libraries. The 25°C consortia were dominated by Vibrio, Idiomarina, Marinobacter, Alcanivorax, and Thalassospira species, while the 5°C consortia were dominated by several species of the genera Flavobacterium, Alcanivorax, and Oleispira. Most of these genera have been linked to hydrocarbon degradation and have been observed after oil spills. Colwellia and Cycloclasticus, known aromatic degraders, were also found in these enrichments. The addition of Corexit did not have an effect on the active bacterial community structure of the 5°C consortia, while at 25°C, a decrease in the relative abundance of Marinobacter was observed. At 25°C, Thalassospira, Marinobacter, and Idiomarina were present at higher relative abundances in the RNA than DNA libraries, suggesting that they were active in degradation. Similarly, Oleispira was greatly stimulated by the addition of oil at 5°C. IMPORTANCE While dispersants such as Corexit 9500 can be used to treat oil spills, there is still debate on the effectiveness on enhancing oil biodegradation and its potential toxic effect on oil-degrading microbial communities. The results of this study provide some insights on the microbial dynamics of hydrocarbon-degrading bacterial populations in the presence of Corexit 9500. Operational taxonomic unit (OTU) analyses indicated that several OTUs were inhibited by the addition of Corexit. Conversely, a number of OTUs were stimulated by the addition of the dispersant, many of which were identified as known hydrocarbon-degrading bacteria. The results highlight the value of using RNA-based methods to further understand the impact of dispersant on the overall activity of different hydrocarbon-degrading bacterial groups.

scholarly journals Functional Redundancy in Local Spatial Scale Microbial Communities Suggest Stochastic Processes at an Urban Wilderness Preserve in Austin, TX, USA

2020 ◽  
Author(s):  
Justin Stewart ◽  
Amy Ontai ◽  
Kizil Yusoof ◽  
Teresa Bilinski
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Structure Function ◽  
Microbial Communities ◽  
Spatial Scale ◽  
Spatial Scales ◽  
Substrate Utilization ◽  
Carbon Substrate ◽  
Utilization Patterns ◽  
Edaphic Properties

AbstractEmpirical evidence supports selection of soil microbial communities by edaphic properties across large spatial scales, however; less is known as smaller spatial scales (e.g 10s-100s of meters). The goal of this research was to evaluate the relationship between ecosystem characteristics and bacterial community structure/function in soils across small spatial scales in an urban preserve. We employed 16s rRNA gene sequencing, community level physiological profiling (CLPP), and soil chemical analysis to address this goal. We found no significant relationship between gradients in soil characteristics and community structure/function. In contrast, Acidobacteria, Bacteroidetes, and Nitrospirae responded to variation in edaphic properties. Taxa exhibited a wide range in dispersal, supporting our finding of community wide differences in taxonomy. Furthermore, there was high metabolic diversity within the bacterial communities despite preferential metabolism of water-soluble polymers (Tween 40/80). Carbon substrate utilization patterns also suggest dominance of functional generalists. Pairwise comparison of carbon substrate utilization patterns indicates that there are high levels of microbial functional redundancy within soils across the sampling area. Lastly, we found that edaphic properties did not shape the overall community structure and/or function, and our analyses suggest that stochasticity may play a role in bacterial community assembly in soils with the local spatial scale of this research study.Graphical AbstractOne Sentence Summary: Microorganisms at small spatial scales were functionally similar despite subtle differences in community composition.

scholarly journals Effects of land conversion on soil microbial community structure and diversity

2020 ◽  
Author(s):  
Tong Zhang ◽  
Yufei Liu ◽  
xin Sui ◽  
fuqiang Song
Keyword(s):  
Land Use ◽  
Community Structure ◽  
Microbial Community ◽  
Microbial Communities ◽  
Soil Bacteria ◽  
Soil Microbial Communities ◽  
Forest Land ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
The Impact

Abstract Background : To study the impact of land-use change on soil microbial community structure and diversity in Northeast China, three typical land-use types (plough, grassland, and forest), grassland change to forest land and grassland change to plough, in the Qiqihar region of Heilongjiang Province were taken as research objects. Methods : MiSeq high-throughput sequencing technology based on bacterial 16S rRNA and fungal ITS rRNA was used to study the above community structure of soil bacteria and fungi and to explore the relationship between soil bacteria and soil environmental factors. Results : The results showed that the dominant bacterial phyla changed from Actinobacteria to Acidobacteria , the dominant fungal phyla changed from Ascomycetes to Basidiomycetes , and the ECM functional group increased significantly after the grassland was completely changed to forest land. After the grassland was changed to plough, the dominant phyla changed from Actinomycetes to Proteobacteria . The functional groups of pathogens and parasites increased significantly. There was no significant difference in the diversity of soil bacterial communities, and the diversity of fungal communities increased significantly. CCA showed that pH, MC, NO 3 - -N, TP and AP of soil were important factors affecting the composition of soil microbial communities, and changes in land-use patterns changed the physical and chemical properties of soils, thereby affecting the structure and diversity of microbial communities. Conclusions : Our research results clarify the impact of changes in land use on the characteristics of soil microbial communities and provide basic data on the healthy use of land.

scholarly journals Land conversion changes soil microbial community structure and diversity

2020 ◽  
Author(s):  
Tong Zhang ◽  
Yufei Liu ◽  
Xin Sui ◽  
Fuqiang Song
Keyword(s):  
Land Use ◽  
Community Structure ◽  
Microbial Communities ◽  
Soil Microbial Communities ◽  
Community Diversity ◽  
Forest Land ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Significant Difference ◽  
The Impact

Abstract Background: To study the impact of land-use change on soil microbial community structure and diversity in Northeast China, three typical land-use types (plough, grassland, and forest), from grassland change to forest land and grassland change to plough, in the Qiqihar region of Heilongjiang Province were taken as research objects. Methods: MiSeq high-throughput sequencing technology based on bacterial 16S rRNA and fungal ITS rRNA was used to study the above community structure of soil bacteria and fungi and to explore the relationship between soil bacteria and soil environmental factors. Results: The results showed that there was no significant difference in soil bacterial community diversity and fungal community diversity after the grassland was completely changed to forest land. The dominant bacterial phylum changed from Actinobacteria to Acidobacteria, the dominant fungal phylum changed from Ascomycetes to Basidiomycetes, and the ECM functional group increased significantly. After the grassland was changed to plough, there was no significant difference in the diversity of soil bacterial communities, and the diversity of fungal communities increased significantly. The dominant phylum changed from Actinomycetes to Proteobacteria. The dominant phylum was still Ascomycetes, and the functional groups of pathogens and parasites increased significantly. CCA showed that soil pH, MC, NO3--N, TP and AP were important factors affecting the composition of soil microbial communities, and changes in land-use patterns changed the physical and chemical properties of soils, thereby affecting the structure and diversity of microbial communities. Conclusions: Our research results clarify the impact of changes in land use on the characteristics of soil microbial communities and provide basic data on the healthy use of land.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

МАРКЕТИНГОВІ АСПЕКТИ ФУНКЦІОНУВАННЯ ЛІТЕРАТУРНИХ КОНКУРСІВ ТА ПРЕМІЙ

2020 ◽  
pp. 90
Author(s):  
O. Bondar
Keyword(s):  
Publishing House ◽  
Target Audience ◽  
Point Of View ◽  
Information Support ◽  
Literary Field ◽  
Non Profit ◽  
Functional Aspects ◽  
The Media ◽  
Literary Prizes ◽  
The Impact

<p><em>In this study, I have collected and summarized the functional aspects of a literary prize, contest, and rating, which indicate their affiliation with the marketing complex of the publishing house for the first time. For this purpose, I have analyzed and summarized the common concepts of the functioning of literary prizes and contests as advertising tools for publishing activity. Because the previous studies are only focused on the fact of the impact of the prize on the promotion of editions but do not explain it, these aspects have been considered and introduced by me from the book production’s point of view. I investigated that the prizes and the contests in the literary field are effective marketing tools, which meet many publisher’s needs at the same time and can be considered a non-profit form of capital. I have reviewed the works of other authors, who accept that the economic success of the book is rising if the author is a winner of the literary prize or contest. I have found out that the book prize activates the demand for the book, and the literary contest is a tool to track the reader’s reaction to a future publication. In this way, literary prizes and contests can be considered as a way of conducting a marketing dialogue with the target audience. I have focused on the information support of literary national and international prizes and contests by the media, which attracts attention to the book and forms the reader’s interest. The literary prizes and contests are also considered as a way of exploring trends and their changes, familiarization the popular genres among the target audience and fixation the current choice of modern readers. Literary prizes and contests motivate the authors to improve their literary excellence, are the source of new authors and works, and assist in increasing sales of books. However, further research is recommended.</em></p><strong><em>Key words:</em></strong><em> book prize, book rating, literary contest, literary prize, functions of the literary prizes.</em>

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