Rozprawy doktorskie: „Bacterial diversity”

1

Lozupone, Catherine Anne. "Global patterns of bacterial diversity". Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273707.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

2

Powell, James Patrick. "Antibiotic Diversity and Bacterial Resistance". Available to users online at:, 2007. http://hdl.handle.net/10156/1303.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

3

Giaramida, Luca. "Freshwater bacterial diversity, functions and stability". Thesis, Robert Gordon University, 2013. http://hdl.handle.net/10059/843.

Pełny tekst źródła

Streszczenie:

Biodiversity is declining worldwide with detrimental effects on ecosystems functions and services that it sustains. The relationship between biodiversity and freshwater purification remains unclear. Freshwater purification is of paramount importance for humankind as eighty percent of the world’s population is exposed to high levels of threat in terms of water security. Bacteria are the most diverse and abundant organisms on Earth and they play, directly or indirectly, a key role in the majority of ecosystem services including water purification. The current work aimed, in freshwater systems, to unravel the relationships between microbial diversity and: (a) biodegradation of toxic compounds (i.e. specialised function); (b) respiration (i.e. broad function) and; (c) stability of broad functioning. Firstly, preliminary experiments were carried out to establish freshwater sample size to representatively evaluate bacterial communities’ diversity and also suitable natural and man-made toxic compounds for freshwater incubation experiments. Then, the microbial communities’ ability to degrade microcystin-LR was explored in the context of previous exposures and nutrient availability. Finally, we focused on the relationships between diversity and functioning. A decrease in microbial diversity caused a decrease in both broad and specialised ecosystem functions tested. Stability of broad functioning was also negatively affected by a decrease in microbial diversity. Both lakes (Scotland) and rivers (Australia) microcosms experiments resulted in comparable findings suggesting consistent relationships across different freshwater systems. These results highlight that, similarly to macro-organisms (plant and animals), declining diversity of the microbial communities has direct consequences for important ecosystem functioning and services and therefore, microbial diversity should be explicitly considered in all biodiversity conservation debates.

Style APA, Harvard, Vancouver, ISO itp.

4

Cotton, Andrew W. "Biochemical diversity of some bacterial haloalcohol dehalogenases". Thesis, University of Kent, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365223.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

5

Hunt, Dana E. Ph D. Massachusetts Institute of Technology. "Aquatic microenvironments in bacterial ecology and diversity". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43047.

Pełny tekst źródła

Streszczenie:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.
Page 116 blank.
Includes bibliographical references.
Molecular surveys have revealed tremendous bacterial diversity in the world's oceans; yet how do these diverse bacteria with the same essential nutrient requirements co-exist in the same environment? This study examines the role of aquatic microenvironments in generating bacterial diversity: closely related organisms may co-exist in the same environment without competing for resources by a combination of habitat, metabolic, and behavioral differentiation. This hypothesis has been approached from several angles: (i) Within the bacterial family Vibrionaceae is there evidence for microenvironmental specialization or functional differentiation? (ii) Is there small scale clustering of bacteria around phytoplankton in the coastal ocean? Microdiverse clusters (< 1% 16S rRNA gene divergence) of Vibrionaceae were found to be differentially distributed between zooplankton-enriched, particulate, and planktonic water column microenvironments. However microhabitat preferences may not correspond to metabolic capabilities; chitin metabolism was observed to be a near ubiquitous metabolic characteristic of the Vibrionaceae, yet does not appear to be linked to colonization of chitinous zooplankton or particles. Finally, the microscale patchiness of bacterial cells was examined over an annual cycle, revealing seasonal variation and a positive correlation with eukaryotic cell number, suggesting that bacteria may cluster in the nutrient-rich microzones around algae in the environment. This study seeks to answer several fundamental questions about marine bacterial populations: how do closely related species co-exist in the same environment, do bacteria adapt to distinct microscale environments and how important are these microenvironments to bacterial productivity.
by Dana E. Hunt..
Ph.D.

Style APA, Harvard, Vancouver, ISO itp.

6

Stuck, Robert Jason. "THE INFLUENCE OF PHYTOREMEDIATION ON BACTERIAL DIVERSITY". Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1133398530.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

7

Dixit, Sameer M. "Antagonistic activity of probiotic bacteria based on bacterial diversity in the porcine gut". Thesis, View thesis, 2004. http://handle.uws.edu.au:8081/1959.7/35614.

Pełny tekst źródła

Streszczenie:

Diversity analysis of Escherichia coli have routinely utilised isolates obtained by culture of faeces on MacConkey selective media, under the assumption that the diversity identified in faecal isolates are representative of similar diversity in E. coli in the gastrointestinal tract (GIT). This study has addressed this important issue by specifically isolating E. coli from different regions of the gut in pigs and subjecting them to enzymatic multilocus enzyme electrophoresis (MLEE) and molecular virulence factor (VF) analysis to ascertain whether E. coli populations inhabiting different regions of the gut are different from each other. Combination of these results showed that on average, E. coli strains isolated from the upper GIT region (small intestine) of the pig are distinctly different from the E. coli strains isolated from the lower GIT region (large intestine). An important aspect of the finding that faecal E. coli are not truly representative of the diversity in the GIT is the mechanism used by specific clonotypes that have adapted to different geographical habitats to survive challenge from incoming strains.

Style APA, Harvard, Vancouver, ISO itp.

8

Dixit, Sameer M. "Antagonistic activity of probiotic bacteria based on bacterial diversity in the porcine gut". View thesis, 2004. http://handle.uws.edu.au:8081/1959.7/35614.

Pełny tekst źródła

Streszczenie:

Thesis (Ph.D.)--University of Western Sydney, Hawkesbury, 2004.
A thesis presented to the University of Western Sydney, Hawkesbury, Centre for Advanced Food Research, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographies.

Style APA, Harvard, Vancouver, ISO itp.

9

Bayindirli, Cansu. "Environmental influences on marine bacterial diversity and activity". Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59617/.

Pełny tekst źródła

Streszczenie:

In order to facilitate the conservation of biological diversity, a comprehensive knowledge of the microbial ecology of an ecosystem is required. As the vast majority of microbes are not readily culturable, it is necessary to use molecular tools to investigate their diversity and function in the marine ecosystem. Although it provides a vast quantity of data, the information obtained by molecular tools alone is not sufficient to understand the drivers behind the changes in bacterial communities. This study aims to characterize changes in the diversity and activity of the heterotrophic bacterial community in relation to a changing environment, in time and space. Two different sampling strategies were used in order to achieve this goal; an annual time series study at a coastal station (station L4, Western English Channel Observatory (WECO)) and a Lagrangian study following an upwelling plume on its track to off shore (2nd filament, Surface Ocean-Lower Atmosphere Study (SOLAS) - Impact of coastal upwelling on the air-sea exchange of climatically important gases (ICON) cruise). Surface water samples were collected from the time series station L4 of the Western Channel Observatory (50º15'N, 04º13'W; www.westernchannelobservatory.org) every week between 6th April 2009 and 26th April 2010. The respiration rate of the heterotrophic community was determined using Winkler titration to measure the dissolved oxygen content of the < 0.8 μm size-fraction of the seawater. This dataset sits within the larger framework of the Western English Channel bacterial diversity ABSTRACT 2 time series (2003-2009) and the seasonal metagenomic and metatranscriptomic studies associated with this site. The second approach was to investigate the bacterial diversity and activity in a dynamic environment, such as an upwelling region. The upwelling region off the coast of Mauritania is one of the most productive areas of the world ocean, yet little is known of the temporal and spatial variability in prokaryotic community structure and metabolic activity there, and crucially how this contributes to global elemental cycles. During a Natural Environmental Research Council (NERC) SOLAS-funded Lagrangian study, we determined bacterial community structure and production together with total community respiration and production. This part of the study describes the temporal changes in bacterial community structure and its activity, in relation to the complex upwelling environmental conditions (mixing, chlorophyll, dissolved organic and inorganic nutrients). Turbulence and dissolved organic carbon appear to play an important role.

Style APA, Harvard, Vancouver, ISO itp.

10

Lu, Ting. "Bacterial diversity as a biomarker of soil health". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1283192368.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

11

Kinneer, Krista L. "Size fractionation of bacterial functional diversity within soils". Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1095.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains x, 68 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 47-48).

Style APA, Harvard, Vancouver, ISO itp.

12

Gilbert, Janice M. "Examining the link between macrophyte diversity, bacterial diversity, and denitrification function in wetlands". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1086098505.

Pełny tekst źródła

Streszczenie:

Thesis (Ph. D.)--Ohio State University, 2004.
Document formatted into pages; contains xiii, 234 p. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2005 June 1.

Style APA, Harvard, Vancouver, ISO itp.

13

Zhang, Quan-Guo. "Diversity and competitive interactions in experimentally evolved bacterial populations". Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:922d763d-3d66-40c8-96d3-5b8e95e24fe4.

Pełny tekst źródła

Streszczenie:

Laboratory bacterial populations provide ideal opportunities to experimentally test theories in ecology and evolutionary biology. I used a model laboratory microbial system, Pseudomonas fluorescens SBW25, to address an array of questions on the origin, maintenance, and functional role of biodiversity, and the evolution of biotic interactions. My thesis reports experiments with the following conclusions. (1) The extent of diversification in P. fluorescens populations is not affected by the presence of an interspecific competitor P. putida, although the early stage of the diversification in one environment (spatially homogeneous environment) could be speeded up by the competitor. (2) Niche and neutral mechanisms simultaneously contribute to the maintenance of phenotypic diversity in P. fluorescens populations; but the operation of niche processes does not lead to a positive effect of biodiversity on ecosystem functioning. (3) The competitive interactions among bacterial phenotypes are generally transitive, and competitive hierarchies inferred from pair-wise competition are fairly consistent to those from multi-species competition. (4) The niche complementarity and selection effects evaluated by random assembly biodiversity experiments can be used to predict the functional consequences of particular non-random species extinction scenarios. (5) P. fluorescens does not show an evolutionary trade-off in using several carbon substrates (glucose, galactose and trehalose), and evolution in environments containing these resources results in imperfect generalists; migration among populations may speed up fitness evolution of some generalists. (6) Biofilm formation at the air-broth interface by wrinkly spreader phenotypes in P. fluorescens is a cooperative behaviour which is costly to individuals but benefits the group; this behaviour could be exploited by smooth morph phenotypes. The cooperators and cheats in this system show reciprocal antagonistic coevolution in resistance and cheating performance.

Style APA, Harvard, Vancouver, ISO itp.

14

Ashforth, Elizabeth Jane. "Bacterial diversity in an arenicola marina L. bioturbated mesocosm". Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500948.

Pełny tekst źródła

Streszczenie:

Arenicola marina (lugworms) are intertidal marine polychaete worms. Ecologically lugworms are responsible for increasing the permeability of the sand, sediment oxygenation and speeding up carbon cycling via the breakdown of buried organic matter. The worms themselves contain polyunsaturated fatty acids that are commercially important in the aquaculture of fin and shellfish. There is, however, some debate over the principal carbon source for the worms themselves. The aim was to investigate the bacterial dynamics in a polychaete worm growth mesocosm and determine the potential contribution of polyunsaturated fatty acid biosynthesis by bacteria to the nutrition of Arenicola marina.

Style APA, Harvard, Vancouver, ISO itp.

15

Hodder, Karl Russell. "The diversity of soil bacterial communities within the Ecotron". Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343965.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

16

Lawler, Stephanie Nichole. "Characterization of Bacterial Diversity in Cold-Water Anthothelidae Corals". Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6295.

Pełny tekst źródła

Streszczenie:

Cold-water corals, similar to tropical corals, contain a diverse and complex microbial landscape. Comprised of vital microscopic organisms (i.e. bacteria, viruses, archaea), the coral microbiome is a driving factor in the proliferation and survival of the coral host. Bacteria provide essential biological functions within coral holobionts, facilitating increased nutrient utilization and production of antimicrobial compounds. To date, few cold-water octocoral species have been analyzed to explore the diversity and abundance of their microbial associates. For this study, 23 samples of the family Anthothelidae were collected from Norfolk (n = 12) and Baltimore Canyons (n = 11) from the western Atlantic in August 2012 and May 2013. Genetic testing found that these samples comprised two Anthothela species (Anthothela grandiflora and Anthothela sp.) and a new genus. DNA was extracted and sequenced with primers targeting the V4-V5 variable region of the 16S rRNA gene using 454 pyrosequencing with GS FLX Titanium chemistry. Results demonstrated that the host genus was the primary driver of bacterial composition. The new coral genus, dominated by Alteromonadales and Pirellulales, had much higher species richness and a distinct bacterial community compared to Anthothela samples. Anthothela species had very similar bacterial communities, dominated by Oceanospirillales and Spirochaetes. Core bacterial diversity present across 90% of the Anthothela samples revealed genus-level conservation. This core included unclassified Oceanospirillales, Kiloniellales, Campylobacterales, and Spirochaeta; the functional abilities of which contribute to a nearly complete nitrogen cycle. Dominant bacterial members of the new coral genus also had functional capabilities in nitrogen cycling. Overall, many of the bacterial associates identified in this study have the potential to contribute to the acquisition and cycling of nutrients within the coral holobiont.

Style APA, Harvard, Vancouver, ISO itp.

17

Tydings, Heather Anne. "Identification and Optimization of the Antagonistic Potential of Native Spinach Microbiota towards Escherichia coli O157:H7". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/43364.

Pełny tekst źródła

Streszczenie:

Leafy greens such as spinach have been the object of several recent food-borne pathogen outbreaks. The purpose of this study was to isolate bacteria spinach epiphytic bacteria that inhibit growth of E. coli O157:H7, which we describe as antagonism. The mechanism of antagonism was investigated and we attempted to improve the antagonistic potential in vitro and on spinach leaves when cellobiose, a carbon source utilized by the antagonists but not E. coli O157:H7, was added. There were larger culturable populations of bacteria on the leaves of savoyed cultivars compared to flat. From the isolated colonies, 47 displayed antagonism towards E.coli O157:H7, and were identified as members of 11 different genera and sixteen species. A representative isolate from each species was evaluated for three possible mechanisms of antagonism: acid production, secretion of an inhibitory compounds or secreted protease. The majority (14/16) produced at least a moderate level of acid. Two of these strains, Paenibacillus polymyxa and Pseudomonas espejiana, were found to secrete a non- protease antagonistic compound. These antagonists varied in their reduction of E.coli O157:H7 numbers in vitro, but all significantly reduced numbers in 48 hours of co-culturing in nutrient rich media. Five antagonists resulted in a significant reduction in E.coli O157:H7 populations when co-cultured on spinach leaves. Application of cellobiose did not improve the amount of antagonism in vitro or on the leaf surface after 24 hours.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

18

Luo, Chengwei. "Development of algorithms for metagenomics and applications to the study of evolutionary processes that maintain microbial biodiversity". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47730.

Pełny tekst źródła

Streszczenie:

Understanding microbial evolution lies at the heart of microbiology and environmental sciences. Numerous studies have been dedicated to elucidating the underlying mechanisms that create microbial genetic diversity and adaptation. However, due to technical limitations such as the high level of uncultured cells in almost every natural habitat, most of current knowledge is primarily based on axenic cultures grown under laboratory conditions, which typically do not simulate well the natural environment. How well the knowledge from isolates translates to in-situ processes and natural microbial communities remains essentially speculative. The recent development of culture-independent genomic techniques (aka metagenomics) provides possibilities to bypass some of these limitations and provide new insights into microbial evolution in-situ. To date, most of metagenomic studies have been focused on a few reduced-diversity model communities, e.g., acid mine drainage. Highly complex communities such as those of soil and sediment habitats remain comparatively less understood. Furthermore, a great power of metagenomics, which has not been fully capitalized yet, is the ability to follow the evolution of natural microbial communities over time and environmental perturbations, i.e., times-series metagenomics. Although the recent developments in DNA sequencing technologies have enabled (inexpensive) time-series studies, the bioinformatics approaches to analyze the resulting data have clearly fallen behind. Taken together, to scale up metagenomics for complex community studies, three major challenges remain: 1) the difficulty to process and analyze massive short read sequencing data, often at the terabyte level; 2) the difficulty to effectively assemble genomes from complex metagenomes; and 3) the lack of methods for tracking genotypes and mutational events such as horizontal gene transfer (HGT) through time. Therefore, developing efficient bioinformatics approaches to address these challenges represents an important and timely issue. This thesis aimed to develop novel bioinformatics pipelines and algorithms for high performance computing, and, subsequently, apply these tools to natural microbial communities to generate quantitative insights into the relative importance of the molecular mechanisms creating or maintaining microbial diversity. The tools are not specific to a particular habitat or group of organisms and thus, can be broadly used to advance our understanding of microbial evolution in different settings. In particular, the comparative whole-genome analysis of 24 Escherichia isolates form various habitats, including human and non-human associated habitats such as freshwater ecosystems and beaches, showed that organisms with more similar ecologies tend to exchange more genes, which has important implications for the prokaryotic species concept. To more directly test these findings from isolates and quantify the patterns of genetic exchange among co-occurring populations, three years of time-series metagenomics data from planktonic samples from Lake Lanier (Atlanta, GA) were analyzed. For this, it was first important to develop bioinformatics algorithms to robustly assemble population genomes from complex community metagenomes, identify the phylogenetic affiliation of assembled genome and contig sequences, and detect horizontal gene transfer among these sequences. Using these novel algorithms, in situ bacterial lineage evolution was quantitatively assessed, especially with respect to whether or not ecologically distinct lineages evolve according to the recently proposed fragmented speciation model (Retchless and Lawrence, Science 2008). Evidence in support of this model was rarely observed. Instead, it appeared that rampant HGT disseminated ecologically important genes within the population, maintaining intra-population diversity. By expanding the previous approaches to include methods to assess differential gene abundance and selection pressure between samples, it was possible to quantify how soil microbial communities respond to a decade of warming by 2 0C, which simulated the predicted effects of climate change. It was found that the heated communities showed significant shifts in composition and predicted metabolism, reflecting the release of additional soil carbon compared to the unheated (control) communities, and these shifts were community-wide as opposed to being attributable to a few taxa. These findings indicated that the microbial communities of temperate grassland soils play important roles in mediating the feedback responses to climate change. Collectively, the findings presented here advance our understanding of the modes and tempo of microbial community adaptation to environmental perturbations and have important implications for better modeling the microbial diversity on the planet. The bioinformatics algorithms and approaches developed as part of this thesis are expected to facilitate future genomic and metagenomic studies across the fields of microbiology, ecology, evolution and engineering.

Style APA, Harvard, Vancouver, ISO itp.

19

Roth, McKenzie L. "Analysis of Bacterial Abundance and Species Diversity in Various Soils". Ashland University Honors Theses / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=auhonors1355166102.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

20

Zul, Delita. "Determinants of the Bacterial Diversity in Manipulated and Natural Soils". Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-82880.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

21

Suvekbala, Vemparthan [Verfasser]. "Physiology and biochemical diversity of bacterial cholate degradation / Vemparthan Suvekbala". Konstanz : Bibliothek der Universität Konstanz, 2011. http://d-nb.info/1023649934/34.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

22

Mansfield, Fiona Kerrie. "Allometric scaling in bacterial populations : cell size, distribution and diversity". Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424704.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

23

Bell, Thomas. "Diversity and functioning of the bacterial communities inhabiting treehole ecosystems". Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427899.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

24

Lowe, Peter Richard. "Molecular detection and analysis of the diversity of bacterial dehalogenases". Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368833.

Pełny tekst źródła

Streszczenie:

The identification and isolation of bacteria capable of dehalogenating highly chlorinated aromatic compounds is currently a time consuming process, therefore the ability to predict the potential of a site to naturally remediate contamination is limited. This work has assessed a selection of modern molecular biological techniques to detect the presence of specific dehalogenase enzymes or the genes encoding them, as an indicator of a contaminated site's potential to perform remediation naturally. DNA and protein based detection strategies were tested in a variety of formats. DNA detection of dehalogenase genes was assessed by varieties of hybridisation probing and PCR detection. Protein based detection utilised specific antibody based detection of dehalogenases from bacterial proteomes. A combined technique exploiting the specificity of antibody detection and the sensitivity of PCR amplification was assessed by ribosomal display. DNA based detection techniques demonstrated a high sensitivity but lacked the required level of specificity for use in routine testing, with the exception of single specific primer PCR which was demonstrated to detect specific changes in a bacterial population following contamination. Protein based detection lacked the sensitivity necessary for a field based detection system but the potential for specifically fingerprinting bacterial species was observed. The ribosomal display technique, although combining sensitivity and specificity, could not be fully evaluated during the course of this work.

Style APA, Harvard, Vancouver, ISO itp.

25

Costa, Sara Daniela Azevedo. "Diversity of the cutaneous bacterial community in the Perez’ frog". Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12634.

Pełny tekst źródła

Streszczenie:

Mestrado em Ecologia Aplicada
Amphibian skin holds a resident bacterial community in the skin surface may confer amphibian species tolerance to environmental stressors. Exposure to chemical contamination may cause direct effects to the amphibians but, simultaneously, may reduce skin bacterial diversity and consequently alter the sensitivity of amphibians to future environmental stressors. Understanding the structure, dynamics and specificity of this microbial community is needed to engage a better and broader protection of amphibians. Accordingly, the present study aimed at investigating the skin-associated bacterial community of the Perez´s frog Pelophylax perezi (Seoane) looking at among and within population variation. To attain this main goal the outer microbiome of the frogs were characterize by culture independent method (PCR/DGGE) and assessing the cultivable portion of bacteria. Furthermore, to evaluate the effects caused by exposure to chemical contamination in the skin bacterial community, some bacterial isolates were exposed to a rich metal contaminated effluent. Skin swabs for sampling symbiotic skin bacteria were collected from 28 amphibian individuals from five different ponds, one of them a metal-rich contaminated effluent (Ribeira da Agua Forte, Aljustrel). For each sampling site physical and chemical characterization of water samples was carried out. A culture independent method showed a characteristic profile in frogs from contaminated site and that both intra- and inter-population variability exist in amphibian skin microbiome. Assessing the cultivable portion of bacteria, microbial concentration per amphibian varied within animals from the same environment and between animals from different environments. Results revealed low diversity and bacterial density (CFU/ frog swab sample) on individuals from metal contaminated site. Isolated bacteria were genetically identified based on 16S rRNA gene sequence. Ecotoxicological assays exposing 30 bacterial isolates to the metal contaminated effluent showed that the percentage of resistant isolates was higher in frogs from the contaminated site. It was also observed that those bacteria exposed to effluent presented a delay in their growth rate.
A pele de alguns anfíbios possui uma comunidade bacteriana residente que pode conferir tolerância a stress ambiental. A contaminação química pode causar efeitos adversos diretos em anfíbios, mas ao mesmo tempo pode reduzir a diversidade bacteriana da pele e, consequentemente, alterar a sensibilidade destes organismos a futuras perturbações ambientais. Compreender a estrutura, dinâmica e especificidade desta comunidade microbiana é necessário para desenvolver uma melhor e mais ampla proteção deste grupo de organismos. Assim, o presente estudo teve como objetivo geral investigar a comunidade bacteriana associada à pele da rã verde comum Pelophylax perezi (Seoane) através da análise da variação intra- e inter populacional. Para alcançar este objetivo o microbioma exterior das rãs foi caracterizado pelo método independente de cultura (PCR / DGGE) e avaliada também a parte cultivável de bactérias. Além disso, para avaliar os efeitos causados pela exposição a contaminação química na comunidade bacteriana da pele, 30 isolados bacterianos foram expostos a um efluente ácido e rico em metais. As zaragatoas para amostrar as bactérias simbióticas da pele dos anfíbios foram recolhidas em 28 indivíduos de cinco locais diferentes, um deles impactado por um efluente ácido e rico em metais (Ribeira da Água Forte, Aljustrel). Para cada local de amostragem foi realizada a caracterização físico-química de amostras de água. O método independente de cultura mostrou um perfil característico de rãs do local contaminado e que a variabilidade tanto intra- e inter- populacional existe no microbioma da pele da rã P. perezi, no entanto, a última parece ser maior do que o anterior. Avaliando a porção cultivável de bactérias, a concentração microbiana por anfíbio varia entre animais do mesmo meio e entre os animais de diferentes ambientes. Os resultados revelaram uma baixa diversidade e densidade de bactérias (UFC / zaragatoa) em indivíduos que habitam o local contaminado por metais. As bactérias isoladas foram geneticamente identificadas com base na sequência do gene de rRNA 16S. O ensaio ecotoxicológico de exposição de isolados bacterianos ao efluente ácido e rico em metais mostrou que a percentagem de isolados resistentes foi maior em isolados provenientes de animais da área impactada pelo efluente. Foi ainda observado que isolados bacterianos quando expostos ao efluente têm um atraso na sua taxa de crescimento comparativamente ao controlo.

Style APA, Harvard, Vancouver, ISO itp.

26

Kang, Seong-San. "Bacterial Diversity as a Predictor of Beef Quality and Safety". Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/82885.

Pełny tekst źródła

Streszczenie:

Shiga toxin-producing Escherichia coli (STEC) is an important foodborne and regulatory pathogen in the beef industry. This study used high throughput sequencing technology to provide deeper analysis of changes in bacterial communities and subsequent effect on the presence of STEC throughout beef processing in Australian abattoirs. The 16S rRNA gene profiling demonstrated that investigating ecological shifts within bacterial communities can provide insights into controlling STEC contamination and improving efficiency of STEC detection and isolation.

Style APA, Harvard, Vancouver, ISO itp.

27

Peter, Hannes. "Diversity and Ecosystem Functioning : Redundancy and Resilience in Freshwater Bacterial Communities". Doctoral thesis, Uppsala universitet, Limnologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160780.

Pełny tekst źródła

Streszczenie:

Bacteria are immensely diverse and hold key-positions in essentially all biogeochemical cycles. In freshwater ecosystems, bacteria degrade and mineralize organic compounds, linking the pool of dissolved organic matter to higher trophic levels. Aware of the global biodiversity loss, ecologists have started identifying the relationship of diversity and ecosystem functioning. Central to this is the question if species can functionally replace other species, hence being functionally redundant. Functional redundancy might allow communities to maintain functioning when diversity is lost. Due to their large numbers and great diversity, bacterial communities have been suspected to harbor large amounts of redundancy. The central aim of this thesis is to investigate the coupling of diversity and ecosystem functioning of bacterial communities and to understand how environmental perturbation affects this relationship. I manipulated the diversity of complex communities by a dilution technique, and measured the performance of bacterioplankton and biofilm-forming communities at different diversities. Reduction of bacterial diversity differently affected different functions, and that the presence or absence of certain species might be causing this pattern. However, for ecosystems to function, the interplay of multiple functions, i.e. multifunctionality, has to be sustained over long periods of time. In bacterial biofilm communities reduced diversity affected multifunctionality, as reflected by extracellular enzyme activities. A continuous cultivation system was used to address the importance of diversity for resistance and resilience upon environmental perturbation. The analysis of co-occurrence of bacterial taxa showed that the communities form a dense network before the perturbation and that these patterns are disturbed by the environmental perturbation. The final chapter of the thesis presents experimental evidence for the positive effects of temporal and spatial refuges for bacterial communities and the functions they provide. Overall, I found several indications for a lower amount of functional redundancy as previously assumed and it becomes apparent from this thesis that a multifunctional perspective and the consideration of environmental heterogeneity is pivotal.

Style APA, Harvard, Vancouver, ISO itp.

28

Zhang, Li, i n/a. "Bacterial Diversity of Australian Exotic Pine Forest Soil and Leaf Litter". Griffith University. School of Biomolecular and Biomedical Science, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20071128.094745.

Pełny tekst źródła

Streszczenie:

Forest plantations, widely grown for wood production, involve the selective promotion of single tree species, or replacement of natural species by exotic tree species. Slash pine (Pinus elliottii) has been chosen for reforestation of infertile sandy soils in southeast Queensland, Australia. These exotic pine plantations minimise soil and water losses, and are important scientific study sites. The soil environment of these plantations, though devoid of sufficient nutrients, oxygen and other factors, harbours innumerable bacteria that may play a crucial role in maintaining soil quality and ecosystem functions. These soil microorganisms also have the potential for use as sensitive biological indicators to reflect environmental changes. It is therefore essential to understand the interrelationships amongst bacterial communities and their environment by assessing their structural and functional diversity, and their responses to disturbances. The microbial community of an exotic pine plantation of subtropical Australia was analysed by both culture-dependent and culture-independent methods. In this study, a leaf litter-soil core sample (25 cm x 40 cm) was collected from a 22-year-old slash pine plantation in southeast Queensland, Australia in October, 2003. The core sample was divided into three fractions, namely, L layer leaf litter, F layer leaf litter, and forest soil 0-10 cm. In the culture-independent study, a modified DNA extraction and purification method was used to obtain highly purified high-molecular-weight DNA. This DNA was successfully used to amplify bacterial 16S rRNA genes with universal primers Fd1 and R6, to produce products of approximately 1500 bp. PCRamplified 16S rRNA genes were subsequently cloned and a total of 194 clones from leaf litter and soil were partially sequenced (about 510 bp). The 16S rRNA gene sequences were analysed and grouped into several phylogroups (the sequences with a similarity value ¡Ý 98 % were regarded as phylogenetically similar and grouped into one phylogroup). Sequencing representatives (¡Ö 1400 nucleotides) from each phylogenetic group confirmed that five bacterial phyla were represented in the forest soil clone library. Phylum Acidobacterium was the most abundant phylogenetic group in terms of the number of clones and accounted for 42 % of all examined soil clones. The Verrucomicrobiales and Proteobacteria were the second and third most abundant phylogenetic groups found in the soil clone libraries, accounting for 12 % and 11 % of the soil clones, respectively. About 8 % of all examined soil clones were Planctomycetes and 27 % of soil clones were phylogenetically unidentified. The large amount of unclassified clone sequences could imply that novel groups of bacteria were present in the forest soil. When the two fractions of leaf litter clone libraries were compared, Firmicutes was the only phylum represented in the L layer leaf litter clone library. Similarly, Firmicutes dominated the F layer leaf litter (79 % of the library), was followed by Proteobacteria (21 %). For the culture-dependent study, a total of 21 isolates which were considered to represent 334 colonies from the leaf litter and forest soil were identified by 16S rRNA gene sequence analysis, indicating that L layer leaf litter and F layer leaf litter were dominated by Firmicutes (48 %) and Proteobacteria (69 %) respectively, and 91 % of the isolates from the forest soil were Firmicutes. Using culture-independent methods, Actinobacteria appeared to be absent from the L and F layer leaf litter and forest soil samples. The results implied that either the nucleic acids of Actinobacteria were difficult to extract or Actinobacteria were over represented in the culture-dependent examinations. Phylum Acidobacteria appeared to be numerically dominant and active members in most soils. However, only one named species had been isolated from an acid mine drainage site and reported by Kishimoto and Tano (1987). Analysis by culture-dependent methods revealed a different bacterial diversity, compared to the bacterial diversity from the 16S rRNA gene clone sequences. The most significant result was the observation that, as revealed by both culture-dependent and culture-independent methods, the bacterial diversity presented in the leaf litter was greatly different from the community of the soil. During the culture-dependent bacterial diversity study, four novel strains were isolated from the forest soil and leaf litter samples and complete characterisations of these novel strains were carried out. Reports on the descriptions of Bacillus decisifrondis strain E5HC-32T from forest soil and Frondicola australicus strain E1HC-02T from L layer leaf litter have been published (appendix). The information provided by assessing the microbial communities in different fractions of leaf litter and forest soil improves our understanding of the phylogenetic relationship between soil and leaf litter. It is suggested, in this study, to perform both culture-dependent and culture-independent methods to characterise the bacterial structure and diversity in forest litter and soil samples, particularly in response to different forest management practices and global change. This study also provides the basis for further functional studies of the forest soil and leaf litter of exotic pine plantation in subtropical Australia.

Style APA, Harvard, Vancouver, ISO itp.

29

Nigro, Lisa M. "Distribution and Diversity of Bacterial Chemolithotrophs in Marine and Freshwater Sediments". Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/NigroLM2006.pdf.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

30

Hoffman, Michele Therese. "Bacterial Endosymbionts of Endophytic Fungi: Diversity, Phylogenetic Structure, and Biotic Interactions". Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/196079.

Pełny tekst źródła

Streszczenie:

This dissertation comprises a series of studies designed to explore the associations between plants and the endophytic fungi they harbor in their above-ground tissues. By viewing endophyte diversity in ecologically and economically important hosts through the lenses of phylogenetic biology, microbiology, and biotechnology, this body of work links plant ecology with newly discovered symbiotic units comprised of endophytic fungi and the bacteria that inhabit them.This work begins with a large-scale survey of endophytic fungi from native and non-native Cupressaceae in Arizona and North Carolina. After isolating over 400 strains of endophytes, I inferred the evolutionary relationships among these fungi using both Bayesian and parsimony analyses. In addition to showing that native and introduced plants contained different endophytes, I found that the endophytes themselves harbor additional microbial symbionts, recovering members of the beta- and gamma-proteobacterial orders Burkholderiales, Xanthomonadales, and Enterobacteriales and numerous novel, previously uncultured bacteria. This work finds that phylogenetically diverse bacterial endosymbionts occur within living hyphae of multiple major lineages of ascomycetous endophytes.A focus on 29 fungal/bacterial associations revealed that bacterial and fungal phylogenies are incongruent with each other and did not reflect the phylogenetic relationships of host plants. Instead, both endophyte and bacterial assemblages were strongly structured by geography, consistent with local horizontal transmission. Endophytes could be cured of their bacterial endosymbionts using antibiotics, providing a tractable experimental system for comparisons of growth and metabolite production under varying conditions. Studies of seven focal fungal/bacterial pairs showed that bacteria could significantly alter growth of fungi at different nutrient and temperature levels in vitro, and that different members of the same bacterial lineages interact with different fungi in different ways.Focusing on one isolate, I then describe for the first time the production of indole-3-acetic acid (IAA) by a non-pathogenic, foliar endophytic fungus (Pestalotiopsis neglecta), suggesting a potential benefit to the host plant harboring this fungus. I show that this fungus is inhabited by an endohyphal bacterium (Luteibacter sp.) and demonstrate that mycelium containing this bacterium produces significantly more IAA in vitro than the fungus alone. I predict that the general biochemical pathway used by the fungal-endohyphal complex is L-tryptophan-dependent and measure effects of IAA production in vivo, focusing on root and shoot growth in tomato seedlings.

Style APA, Harvard, Vancouver, ISO itp.

31

Zhang, Li. "Bacterial Diversity of Australian Exotic Pine Forest Soil and Leaf Litter". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/366994.

Pełny tekst źródła

Streszczenie:

Forest plantations, widely grown for wood production, involve the selective promotion of single tree species, or replacement of natural species by exotic tree species. Slash pine (Pinus elliottii) has been chosen for reforestation of infertile sandy soils in southeast Queensland, Australia. These exotic pine plantations minimise soil and water losses, and are important scientific study sites. The soil environment of these plantations, though devoid of sufficient nutrients, oxygen and other factors, harbours innumerable bacteria that may play a crucial role in maintaining soil quality and ecosystem functions. These soil microorganisms also have the potential for use as sensitive biological indicators to reflect environmental changes. It is therefore essential to understand the interrelationships amongst bacterial communities and their environment by assessing their structural and functional diversity, and their responses to disturbances. The microbial community of an exotic pine plantation of subtropical Australia was analysed by both culture-dependent and culture-independent methods. In this study, a leaf litter-soil core sample (25 cm x 40 cm) was collected from a 22-year-old slash pine plantation in southeast Queensland, Australia in October, 2003. The core sample was divided into three fractions, namely, L layer leaf litter, F layer leaf litter, and forest soil 0-10 cm. In the culture-independent study, a modified DNA extraction and purification method was used to obtain highly purified high-molecular-weight DNA. This DNA was successfully used to amplify bacterial 16S rRNA genes with universal primers Fd1 and R6, to produce products of approximately 1500 bp. PCRamplified 16S rRNA genes were subsequently cloned and a total of 194 clones from leaf litter and soil were partially sequenced (about 510 bp). The 16S rRNA gene sequences were analysed and grouped into several phylogroups (the sequences with a similarity value ¡Ã 98 % were regarded as phylogenetically similar and grouped into one phylogroup). Sequencing representatives (¡Ã– 1400 nucleotides) from each phylogenetic group confirmed that five bacterial phyla were represented in the forest soil clone library. Phylum Acidobacterium was the most abundant phylogenetic group in terms of the number of clones and accounted for 42 % of all examined soil clones. The Verrucomicrobiales and Proteobacteria were the second and third most abundant phylogenetic groups found in the soil clone libraries, accounting for 12 % and 11 % of the soil clones, respectively. About 8 % of all examined soil clones were Planctomycetes and 27 % of soil clones were phylogenetically unidentified. The large amount of unclassified clone sequences could imply that novel groups of bacteria were present in the forest soil. When the two fractions of leaf litter clone libraries were compared, Firmicutes was the only phylum represented in the L layer leaf litter clone library. Similarly, Firmicutes dominated the F layer leaf litter (79 % of the library), was followed by Proteobacteria (21 %). For the culture-dependent study, a total of 21 isolates which were considered to represent 334 colonies from the leaf litter and forest soil were identified by 16S rRNA gene sequence analysis, indicating that L layer leaf litter and F layer leaf litter were dominated by Firmicutes (48 %) and Proteobacteria (69 %) respectively, and 91 % of the isolates from the forest soil were Firmicutes. Using culture-independent methods, Actinobacteria appeared to be absent from the L and F layer leaf litter and forest soil samples. The results implied that either the nucleic acids of Actinobacteria were difficult to extract or Actinobacteria were over represented in the culture-dependent examinations. Phylum Acidobacteria appeared to be numerically dominant and active members in most soils. However, only one named species had been isolated from an acid mine drainage site and reported by Kishimoto and Tano (1987). Analysis by culture-dependent methods revealed a different bacterial diversity, compared to the bacterial diversity from the 16S rRNA gene clone sequences. The most significant result was the observation that, as revealed by both culture-dependent and culture-independent methods, the bacterial diversity presented in the leaf litter was greatly different from the community of the soil. During the culture-dependent bacterial diversity study, four novel strains were isolated from the forest soil and leaf litter samples and complete characterisations of these novel strains were carried out. Reports on the descriptions of Bacillus decisifrondis strain E5HC-32T from forest soil and Frondicola australicus strain E1HC-02T from L layer leaf litter have been published (appendix). The information provided by assessing the microbial communities in different fractions of leaf litter and forest soil improves our understanding of the phylogenetic relationship between soil and leaf litter. It is suggested, in this study, to perform both culture-dependent and culture-independent methods to characterise the bacterial structure and diversity in forest litter and soil samples, particularly in response to different forest management practices and global change. This study also provides the basis for further functional studies of the forest soil and leaf litter of exotic pine plantation in subtropical Australia.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Biomedical Sciences
Faculty of Science and Technology
Full Text

Style APA, Harvard, Vancouver, ISO itp.

32

Petersson-Wolfe, Christina Sonja. "A study of the occurrence, phenotypic and genotypic diversity and both in vitro and in vivo growth responses of Enterococcus spp. isolated from bovine origin". Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1153766262.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

33

Barcenilla, Adela. "Diversity of the butyrate-producing microflora of the human gut". Thesis, Robert Gordon University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310425.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

34

Thomson, Bruce Craig. "Plant Input Effects on the Diversity and Function of Grassland Bacterial Communities". Thesis, University of Newcastle upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485856.

Pełny tekst źródła

Streszczenie:

By decomposing organic matter, bacterial communities are essential for plant growth and ecosystem functioning. Conversely, aboveground plant communities are known to select for particular bacterial communities by depositing C resources of different palatability belowground. Aboveground communities are known drivers of bacterial community structure which in turn affects soil C cycling. However, the exact mechanisms and feedbacks of this intimate relationship remain unclear. This thesis examines the effects of vegetation on bacterial community structure and whether plant driven differences in bacterial community composition affect soil C cycling and substrate utilisation in a grassland soil at the NERC experimental field site, Sourhope, Scotland. Firstly, the effects of vegetation on bacterial community structure .and soil respiration were examined. Bacterial community structure and function were shown to differ depending on the presence or ab~nce of plants. Particularly, differences in the abundances of certain bacteria were observed and soil respiration rates were higher in vegetated soil 'compared to bare soil. These differences in soil CO2-C efflux were attributed to differences in the physiological traits of the dominant bacterial taxa. Next, an assessment of laboratory soil pre-treatments was carried out to establish a suitable microcosm design for analysing soil bacterial communities. The results from this study were then implemented in the design of subsequent experiments to investigate soil bacterial community structure and C functional responses to added substrates. Using soil microcosms it was then investigated whether plant-induced differences in bacterial community structure affected the decomposition of different substrate types and amounts. Also, whether the presence or absence of plants selected for different bacterial community members responsible for the decomposition of labile and recalcitrant substrates added at a high and low concentration. Functional responses were shown to differ depending on soil type, substrate complexity and loading rate. Respiration responses were thought to be due to differences in bacterial community structure between soil treatments. Taxonomic responses also differed depending on the presence or absence of plants, decomposability of substrate and concentration. However, there were no consistent patterns in community changes. Finally, 13C-Iabelled substrates were added to soil with or without vegetation to accurately measure substrate specific respiration and assess priming effects. Also rRNASIP was performed in an attempt to unambiguously identify bacteria responsible for the assimilation of labelled substrates. Following labelled-substrate additions, mineralisation of substrates differed between soil treatments and was dependent on substrate type. Priming effects were strongest in bare soil as in vegetated soil added substrate was preferentially mineralised over native SOM. Both substrate specific respiration and priming effects were thought to be linked to bacterial community composition. Whilst all substrates were rapidly mineralised and significant differences existed between vegetated and bare soils, 13C was not incorporated into RNA with similar efficiency. Using rRNASIP the entire bacterial community in vegetated and bare soils was shown to have utilised 13C-substrates as a general bacterial community shift into enriched gradient fractions was observed. However, similar to initial bacterial diversity, there were differences in the abundances of functionally active bacteria between vegetated and bare soils.

Style APA, Harvard, Vancouver, ISO itp.

35

Bellingham, Nessa Francis. "The use of the bacterial flagellin gene to study diversity amongst pseudomonads". Thesis, Coventry University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297502.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

36

Sengupta, Adti. "Studying Methanotrophic Bacterial Diversity in Ohio Soils Using High-Throughput Sequence Analysis". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1436956336.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

37

Larouche, Julia. "Environmental Influences on the Genetic Diversity of Bacterial Communities in Arctic Streams". ScholarWorks @ UVM, 2009. http://scholarworks.uvm.edu/graddis/131.

Pełny tekst źródła

Streszczenie:

The National Park Service (NPS) Inventory and Monitoring (I&M) Program is designed to collect baseline data on “vital sign” indicators across the entire NPS system. The project presented in this thesis was designed to supplement to efforts of the Artic Network (ARCN) to catalogue the physical, chemical and biological metrics associated with the Stream Communities and Ecosystems vital sign and to foster a better understanding of the basic structure and function of these remote systems. This data is essential to assess the impacts of current and future environmental change in the ARCN parks. The primary objective of this project was to quantify the genetic diversity of microbial communities of selected arctic stream ecosystems. Microbes are a fundamentally important but poorly understood component of arctic stream ecosystems. They are responsible for recycling organic matter and regenerating nutrients that are essential to the food webs of aquatic ecosystems. Recent research (Jorgenson et al. 2002) in the ARCN parks has shown that two fundamentally different lithologies – ultramafic and non-carbonate – influence terrestrial productivity and impart different geochemical characteristics to stream water. Microbes are found in different stream habitats – sediment (epipssamon) and rock (epilithon) biofilms. In this work we test the hypothesis that these differences in lithology and stream habitat influence the genetic diversity of bacterial biofilm communities in arctic streams and whether these patterns can be correlated to stream biogeochemistry. A microbial community fingerprinting method, T-RFLP, as well as 16S rRNA gene sequencing were used to explore the genetic diversity of microbial communities in sediment and epilithic biofilms in stream reaches that drain watersheds with contrasting lithologies in the Noatak National Preserve, Alaska. Differing patterns in bacterial community composition at both the large-scale (lithology) and small-scale (stream habitat) were observed. Non-metric multidimensional scaling (NMDS) ordination of T-RFLP peaks and Analysis of Similarity (ANOSIM) showed a high degree of separation (ANOSIM P < 0.001) between the non-carbonate and ultramafic lithologies, as well as the two habitats, sediment and epilithon. Significant (P < 0.005, Bonferroni corrected) positive correlations were detected between particular nutrients, base cations, and dissolved organic carbon and bacterial community structure unique to each lithology. Although clone libraries indicated high bacterial OTU diversity within and across stream sites, biogeographical patterns were observed depending on locality type. Rarefaction analyses indicated that streams arising from the non-carbonate lithology may be more diverse than streams arising from the ultramafic lithology. Analysis of MOlecular VAriance (AMOVA) indicated that sediment and epilithon samples had genetically different microbial communities (P = 0.01) and taxonomic identifications revealed markedly different bacterial residents between sediment and epilithon habitats. Our results show relationships at large- and small-scales at the landscape level and in ecological niches within a single stream.

Style APA, Harvard, Vancouver, ISO itp.

38

Lad, Ganesh Raoji. "Phenomic and genomic diversity of a bacterial species in a local population". Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/5643/.

Pełny tekst źródła

Streszczenie:

Biology aims to understand life and life processes. DNA is the blueprint of life and hence analysis of DNA sequences is expected to explain the way in which life manifests. The genomes of a large number of organisms have been sequenced and more are being sequenced every day. However, just knowing the DNA sequence does not tell us the manner in which it expresses itself to confer phenotypes on an organism. Hence, after the DNA sequence is obtained, it is important to identify the genes in the sequence, their organisation, their complex interactions and their function in the expression of different phenotypes. Bacteria belonging to the genus Rhizobium exhibit immense genotypic and phenotypic diversity. In this thesis, we look at the difference in the metabolic fingerprints of 72 isolates belonging to the genus Rhizobium isolated from leguminous plants near Wentworth College, University of York. Sequence data from the 72 isolates was used to correlate the phenotypic diversity to the sequence diversity in order to predict the role of genes involved in metabolism of the substrates investigated. Of the 95 substrates investigated, the ability of the strains to utilize only one substrate viz. g-hydroxybutyrate (GHB) showed a near absolute correlation to the presence of two genes in the genome data viz. pRL100135 and pRL100136. The mutation of pRL100135 showed a pronounced decrease in the ability of the test organism to use GHB. The mutation of pRL100136 decreased, but did not abolish, the ability to use GHB. Complementation of mutation by introduction of an intact copy cloned into a plasmid under the control of a strong promoter significantly restored the ability of the mutated test bacterium to utilize GHB to significant levels. The study shows that it is possible to predict the role of genes associated with a phenotype by looking at correlation between the variation in the phenotype in a population and the corresponding gene presence-absence data. However, this approach is both time-consuming and expensive. Of the 95 substrates investigated, only one showed a near-absolute correlation between the appearance of a phenotype and gene presence-absence data. Although an alternate approach to build mutant library and study the effect of mutation in every single gene on a larger array of substrates is possible, that too, would prove expensive. Hence, in conclusion, it can be said that the process of correlating genotype (or specific genes) to phenotypes will probably have to await development of new, cheap, quick and more efficient techniques.

Style APA, Harvard, Vancouver, ISO itp.

39

Stilwell, Peter Robert. "The ecology and evolution of diversity and cooperation in bacterial public-goods". Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/33191.

Pełny tekst źródła

Streszczenie:

Explaining why cooperation exists despite the persistent advantage of cheats has been the focus of much theoretical and empirical attention in biology. Using the bacterium Pseudomonas aeruginosa as a model system for the evolution of cooperation, I investigate two distinct phenomena which may develop our understanding of how cooperation is maintained; 1) tag-based cooperation and diversity; and 2) environmental heterogeneity. The first investigates how diversity in cooperative systems may be a response to the selective pressure exerted by cheating, and how cheats may then regulate communities to maintain diversity: I demonstrate that in competition, tag-based cooperation is able to evade parasitism, provided the public-good is only accessible to producer strains, i.e., the cheat possesses the “wrong” tag. I also demonstrate that cheats can have a marked influence on diversity: In a community of two producer strains with different tags, if a third cheater strain is introduced, it will drive both its own producer and itself extinct. I do not find that the presence of cheats maintains diversity in either structured or unstructured environments, and discuss the possible causes of this. In the second topic of this thesis, I investigate the effect of environmental heterogeneity in resource availability, through space and time, on the evolution of cooperation. Environmental heterogeneity is a ubiquitous feature of natural landscapes, yet its effect on the evolution of cooperation has not been extensively studied. I demonstrate that resource availability heterogeneity, in both time and space, acts to maintain cooperation at higher levels than homogeneous environments of the same total resource value. This effect is due to the covariance between productivity and the cost of cooperation: high resource availability periods and spaces are highly productive, and also incur a relatively lower cost of cooperation.

Style APA, Harvard, Vancouver, ISO itp.

40

Al-Murayati, Haider. "Diversity of the bacterial community and secondary sexual characters in the peacock". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS096/document.

Pełny tekst źródła

Streszczenie:

Les plumes d'oiseaux abritent de nombreux microorganismes qui pourraient être acquis dans l'environnement, ces microorganismes pouvant exercer une sélection intense sur leurs hôtes en réduisant leur fécondité et leur survie. Plusieurs taxons bactériens qui vivent sur des plumes ont la capacité de dégrader la kératine des plumes et causent des dommages à leur structure et peuvent modifier aussi leur coloration. Les oiseaux utilisent des signaux visuels tels que des couleurs vives ou des ornementations exagérées pour la communication socio-sexuelle ainsi que la reconnaissance des espèces. Seuls les individus en bonne santé sont capables de produire des caractères sexuels secondaires exagérés et restent résistants aux parasites débilitants. Le paon (Pavo cristatus) est une espèce polygame qui a plusieurs décorations exagérées, les caractères sexuels secondaires les plus remarquables du paon sont leur traîne décorée avec des ocelles magnifiques qui contiennent trois couleurs irisées différentes. Grâce à une technique basée sur la culture, j'ai isolé la communauté bactérienne des plumes de différentes parties colorées des ocelles de la traîne du paon. L'étude révèle qu'il y a eu une répartition hétérogène des bactéries parmi les différentes parties colorées des ocelles. L'abondance et la prévalence des taxa bactériens spécifiques étaient liées au degré de dégradation des plumes, à l'expression de différents caractères sexuels secondaires, à des changements dans la coloration des ocelles et à l'augmentation de la croissance quotidienne des plumes. En outre, nous avons constaté un petit effet de l'expression de caractères sexuels secondaires sur la proportion sexuelle des couvées avec un biais en faveur des individus masculins. Les travaux présentés dans cette thèse fournissent des preuves que les ocelles de plumes peuvent être considérés comme un signal fiable de la diversité et de l'abondance de bactéries chez le paon. En conséquence, ils représentent une indication pour la qualité individuelle, ce qui permet aux femelles de choisir des mâles avec une communauté bactérienne spécifique
Bird feathers harbour numerous microorganisms that could be acquired from the surrounding environment, these microorganisms may exert intense selection on their hosts by reducing fecundity and survivorship. Several bacterial taxa that live on feathers have the ability to degrade feather keratin and cause damage to feather structure and may alter the feather colouration. Birds use visual signals such as bright colours or exaggerated ornamentation for socio-sexual communication as well as species recognition. Only healthy individuals are able to produce exaggerated secondary sexual characters and still remain resistant to debilitating parasites. Peacocks (Pavo cristatus) is a polygamous species that have different exaggerated ornamentation, the most notable secondary sexual characters of the peacock are their long-decorated trains that comprise the magnificent ocelli which contain three different iridescent colours. Through a culture based technique we isolate feather bacterial community from differently coloured parts of the ocelli of the peacock’s train. The study reveals that there was a heterogeneous distribution of bacteria among the differently coloured parts of ocelli. The abundance and prevalence of specific bacterial taxa was related to the degree of feather degradation, expression of different secondary sexual character, changes in ocelli colouration and daily growth increment. Furthermore, we found a small effect of the expression of secondary sexual characters on biasing of brood sex ratio towards production of more sons than daughters. The work presented in this thesis provide evidence that feather ocelli may consider as a reliable signal of the diversity and the abundance of bacteria in peacock and in consequence indication for the individual quality and that allowing the choosy females to pick males with a specific bacterial community

Style APA, Harvard, Vancouver, ISO itp.

41

Berga, Quintana Mercè. "Assembly Mechanisms in Aquatic Bacterial Communities : The Role of Disturbances, Dispersal and History". Doctoral thesis, Uppsala universitet, Limnologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-207183.

Pełny tekst źródła

Streszczenie:

Environmental conditions, biotic interactions, dispersal and history have been suggested to be important processes influencing the spatial distribution of organisms and thus to affect community assembly. Understanding how these processes influence community assembly is important, particularly because community diversity and composition are suggested to be relevant for ecosystem functioning. Moreover, bacteria are strongly contributing to nutrient and carbon cycle. Bacteria are highly abundant and ubiquitous, and thus it is relevant to study how they are assembled. This thesis aims to gain insight on the role of these processes on aquatic bacterial community assembly, diversity and functioning. The studies included in this thesis involve transplant and microcosm experiments performed in the lab as well as manipulation experiments and field surveys in a natural rock pool systems. Bacterial community composition was addressed by analysis of 16S rRNA gene and community functioning by measuring bacterial production, community respiration and the ability to use different carbon substrates. This thesis highlights that species sorting is a very important assembly mechanism for bacterial communities, but also finds that other processes such as dispersal and history contribute to the patterns observed. Dispersal caused rescuing effects compensating for losses of diversity; at the same time it increased the similarity between communities. Moreover, bacteria have shown a high level of functional plasticity when colonizing a new locality. Interestingly, past environmental conditions explained the structure of bacterial communities better than present-day environmental conditions. Disturbances and biotic interactions are also important in the assembly of communities. Disturbance caused temporary shifts in bacterial function and changes in composition, the magnitude of which depended on the intensity and the frequency of the disturbance. However, natural aquatic bacterial communities showed quite high resilience capacities. Competition can shift the proportion of generalists and specialists species whereas predation or trophic interactions have been found to decrease diversity and to modify the importance of stochasticity. Both caused alterations of community functioning. Finally, this thesis shows that the diversity-functioning relationship is context dependent. Further research should be directed to understanding the intensity and direction of changes in composition and how this affects the functionality of bacterial communities

Style APA, Harvard, Vancouver, ISO itp.

42

Kanso, Sungwan, i n/a. "Molecular Studies of Bacterial Communities in the Great Artesian Basin Aquifers". Griffith University. School of Biomolecular and Biomedical Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040219.140509.

Pełny tekst źródła

Streszczenie:

16S rRNA gene analysis has shown that bacterial diversity in the GAB bores studied was limited to the genera Hydrogenobacter in the phylum Aquificae, Thermus in the phylum Deinococcus-Thermus, Desulfotomaculum in the phylum Firmicutes, the alpha-, beta- and gamma-classes of the phylum Proteobacteria and the phylum Nitrospirae. There was no clone closely related to members of the delta-proteobacteria and epsilon-proteobacteria classes detected. The number of bacterial strains directly isolated from the Fairlea and the Cooinda bores were far less than the numbers of distinctive phylotypes detected by the 16S rRNA gene characterisation. In addition none of the bacterial strains directly isolated from the water samples were represented in the 16S rRNA gene clone libraries. Similar discrepancies between the bacterial populations obtained from the 16S rRNA gene analysis and those obtained from direct isolation have been reported in the literature (Dunbar et al., 1999; Kampfer et al., 1996; Suzuki et al., 1997; Ward et al., 1998; Ward et al., 1997). However, in general, the phyla with which the isolates were affiliated were the same as those phyla to which the clones belonged. The environmental changes introduced (by bringing the artesian water up to the surface and exposing it to four types of metal coupons made of carbon steels identified by codes ASTM-A53B, ASTM-A53, AS-1074 and AS-1396 and commonly used in bore casings) led to changes in the bacterial community structures. In general, the species which proliferated in the communities before and after the changes were different. The diversity of the bacterial species in the community decreased following the environmental changes. Clones dominating the clone libraries constructed from newly established bacterial communities also differed from the clones dominating the libraries constructed from the bacterial communities which had existed naturally in the bores. These trends toward change in the bacterial communities were observed at both the Fairlea and the Cooinda bore sites. All four metal types incubated in the Fairlea bore water lost between 3.4 and 4.7% of their original weight. In contrast none of the metals incubated in Cooinda bore water lost weight. Clone library A1 showed that the natural population of the Fairlea bore was dominated by clone A1-3, which represented a novel species related to the isolate boom-7m-04. But after metal incubation (and recording of the metal weight loss), the bacterial community was dominated by clone PKA34B, which has a 95% similarity in its 16S rRNA gene sequence with Desulfotomaculum putei. Desulfotomaculum species are known to cause metal corrosion due to their byproduct H2S. But the low level of phylogenetic relatedness found does not provide enough information to speculate on whether the species represented by clone PKA34B is a member of the genus Desulfotomaculum or not. However, the fact that clone PKA34B dominated the PKA clone library by 50% makes the species it represents a suspected candidate likely to be involved with the metal weight loss at the Fairlea bore. In contrast, clone library 4381 showed that the natural population of the Cooinda bore was dominated by clone 4381-15 representing a species distantly related to a hydrogen oxidiser Hydrogenophaga flava (95% similarity). The dominating clone of the new community formed after metal incubation was clone COO25, which has 99% similarity with Thermus species that have not been reported to be involved with metal corrosion to my knowledge. In this project detection, identification and comparative quantification by 16S rRNA gene-targeted PCR probing with probes 23B and 34B were successfully developed for a Leptothrix-like species and for a Desulfotomaculum-like species represented by clones PKA23B and PKA34B respectively. This method of probing permits a fast, sensitive and reproducible detection, identification and at least a comparative quantification of the bacteria in the environment without the need for culturing. Therefore it is extremely suitable for use in bacterial population monitoring. PCR probing with the 34B probe has a potential commercial use as a means of screening for bores with a potential high risk of corrosion due to this Desulfotomaculum-like species. Direct isolation of bacteria from the GAB water has resulted in the isolation of seven strains from the Fairlea bore and eight from the Cooinda bore. Among these isolates, three novel strains were studied in detail. Reports on the characterisation of strain FaiI4T (T=Type strain) from the Fairlea bore (Kanso & Patel, 2003) and strain CooI3BT from the Cooinda bore have been published (Kanso et al., 2002). The data generated during this project add to our current information and extend our knowledge about the bacterial communities of the GAB's sub-surface environment. This information will provide a basis for further ecological studies of the GAB. Studies on involvement of certain groups of bacteria with the corrosion of metals used in bore casings could provide a foundation for further studies to develop maintenance and managing strategies for the GAB bores.

Style APA, Harvard, Vancouver, ISO itp.

43

Kanso, Sungwan. "Molecular Studies of Bacterial Communities in the Great Artesian Basin Aquifers". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/366613.

Pełny tekst źródła

Streszczenie:

16S rRNA gene analysis has shown that bacterial diversity in the GAB bores studied was limited to the genera Hydrogenobacter in the phylum Aquificae, Thermus in the phylum Deinococcus-Thermus, Desulfotomaculum in the phylum Firmicutes, the alpha-, beta- and gamma-classes of the phylum Proteobacteria and the phylum Nitrospirae. There was no clone closely related to members of the delta-proteobacteria and epsilon-proteobacteria classes detected. The number of bacterial strains directly isolated from the Fairlea and the Cooinda bores were far less than the numbers of distinctive phylotypes detected by the 16S rRNA gene characterisation. In addition none of the bacterial strains directly isolated from the water samples were represented in the 16S rRNA gene clone libraries. Similar discrepancies between the bacterial populations obtained from the 16S rRNA gene analysis and those obtained from direct isolation have been reported in the literature (Dunbar et al., 1999; Kampfer et al., 1996; Suzuki et al., 1997; Ward et al., 1998; Ward et al., 1997). However, in general, the phyla with which the isolates were affiliated were the same as those phyla to which the clones belonged. The environmental changes introduced (by bringing the artesian water up to the surface and exposing it to four types of metal coupons made of carbon steels identified by codes ASTM-A53B, ASTM-A53, AS-1074 and AS-1396 and commonly used in bore casings) led to changes in the bacterial community structures. In general, the species which proliferated in the communities before and after the changes were different. The diversity of the bacterial species in the community decreased following the environmental changes. Clones dominating the clone libraries constructed from newly established bacterial communities also differed from the clones dominating the libraries constructed from the bacterial communities which had existed naturally in the bores. These trends toward change in the bacterial communities were observed at both the Fairlea and the Cooinda bore sites. All four metal types incubated in the Fairlea bore water lost between 3.4 and 4.7% of their original weight. In contrast none of the metals incubated in Cooinda bore water lost weight. Clone library A1 showed that the natural population of the Fairlea bore was dominated by clone A1-3, which represented a novel species related to the isolate boom-7m-04. But after metal incubation (and recording of the metal weight loss), the bacterial community was dominated by clone PKA34B, which has a 95% similarity in its 16S rRNA gene sequence with Desulfotomaculum putei. Desulfotomaculum species are known to cause metal corrosion due to their byproduct H2S. But the low level of phylogenetic relatedness found does not provide enough information to speculate on whether the species represented by clone PKA34B is a member of the genus Desulfotomaculum or not. However, the fact that clone PKA34B dominated the PKA clone library by 50% makes the species it represents a suspected candidate likely to be involved with the metal weight loss at the Fairlea bore. In contrast, clone library 4381 showed that the natural population of the Cooinda bore was dominated by clone 4381-15 representing a species distantly related to a hydrogen oxidiser Hydrogenophaga flava (95% similarity). The dominating clone of the new community formed after metal incubation was clone COO25, which has 99% similarity with Thermus species that have not been reported to be involved with metal corrosion to my knowledge. In this project detection, identification and comparative quantification by 16S rRNA gene-targeted PCR probing with probes 23B and 34B were successfully developed for a Leptothrix-like species and for a Desulfotomaculum-like species represented by clones PKA23B and PKA34B respectively. This method of probing permits a fast, sensitive and reproducible detection, identification and at least a comparative quantification of the bacteria in the environment without the need for culturing. Therefore it is extremely suitable for use in bacterial population monitoring. PCR probing with the 34B probe has a potential commercial use as a means of screening for bores with a potential high risk of corrosion due to this Desulfotomaculum-like species. Direct isolation of bacteria from the GAB water has resulted in the isolation of seven strains from the Fairlea bore and eight from the Cooinda bore. Among these isolates, three novel strains were studied in detail. Reports on the characterisation of strain FaiI4T (T=Type strain) from the Fairlea bore (Kanso & Patel, 2003) and strain CooI3BT from the Cooinda bore have been published (Kanso et al., 2002). The data generated during this project add to our current information and extend our knowledge about the bacterial communities of the GAB's sub-surface environment. This information will provide a basis for further ecological studies of the GAB. Studies on involvement of certain groups of bacteria with the corrosion of metals used in bore casings could provide a foundation for further studies to develop maintenance and managing strategies for the GAB bores.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Biomedical Sciences
Full Text

Style APA, Harvard, Vancouver, ISO itp.

44

Shams, Malek. "Assessing the diversity of agrobacterial populations". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00984505.

Pełny tekst źródła

Streszczenie:

Agrobacterium are Alphaproteobacteria common in most soils that closely interact with plants in two respects. Firstly, they are rhizospheric bacteria saprophytically living in the rhizosphere of numerous plants and they are likely beneficial to plants. Secondly, when they harbor a dispensable Ti plasmid (i.e. tumor inducing plasmid), agrobacteria are plant pathogens able to cause the crown gall disease to most dicots and gymnosperms and some monocots. An epidemiological survey of crown gall thus also requires expert determination of the Agrobacterium taxonomy. In this thesis we evaluated the usefulness of MALDI-TOF MS technique as a high throughput tool to determine and classify agrobacteria. Then we set up a recA-based PCR method to accurately and exhaustively assess agrobacterial diversity either of isolated agrobacteria or directly in various biotopes. We applied standard biochemical, recA-based and Ti plasmid-based identification methods to study the prevalence of pathogenic and non-pathogenic agrobacteria at the country and local scales. Finally, we tested whether analyzing the internal composition of recA amplicons could be a way to directly assess the micro-diversity of agrobacterial populations using cloning sequencing or pyrosequencing approaches. The later methodology was applied to establish the actual field diversity of Agrobacterium and to evaluate whether plant genotypes differentially select agrobacteria in their root systems, providing first data upon biotic factors shaping the population structure of agrobacteria

Style APA, Harvard, Vancouver, ISO itp.

45

O'Neill, Andrew. "The microbial diversity of wetland sediments constructed to treat acid mine drainage as determined by molecular techniques /". St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16527.pdf.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

46

An, Shu. "Characterization of bacterial diversity in three oligotrophic environments using high-throughput sequencing technology". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00859417.

Pełny tekst źródła

Streszczenie:

Oligotrophic ecosystems can be loosely defined as environments that exhibit low ambient nutrient levels. During my thesis, I used 454 DNA pyrosequencing of partial 16S rDNA to explore the bacterial diversity in three different oligotrophic environments, including A. surface desert soil, B. Asian sandstorm dust and C. a section of the city of Paris's drinking water distribution system.A. Arid regions represent nearly 30% of the Earth's terrestrial surface. The living conditions at the surface of deserts are a challenge for microorganisms, as there is little available water and/or carbon, a very large range of temperatures and high exposure to UV irradiation from the Sun. In surface sand samples from two large Asian deserts, unexpectedly large bacterial diversity residing was revealed. Sequences belonging to the Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria phyla were the most abundant. An increase in phylotype numbers with increasing C/N ratio was noted, suggesting a possible role in the bacterial richness of these desert sand environments.B. Desert sandstorms are a meteorological phenomenon which have been postulated affect the Earth's climate and public health. We examined the particle-associated (dust and sand-associated) bacterial populations of atmospheric sand in the absence (as control) and presence of sandstorms in five Asian cities. Greater than 90% of the sequences can be classified as representing bacteria belonging to four phyla: Proteobacteria, Bacteriodetes, Actinobacteria and Firmicutes. Principal component analyses showed that the sandstorm-associated bacterial populations were clustered by sampling year, rather than location. Members belonging to nine bacterial genera (Massilia, Planococcus, Carnobacterium, Planomicrobium, Pontibacter, Pedobacter, Lysobacter, Sanguibacter, Ohtaekwangia) were observed to increase in sand-associated samples from sandstorms, versus the controls. C. We characterized the bacterial communities in three water and three biofilm samples from one part of the Parisian drinking water distribution system. A dramatic change in bacterial population in the water during flow through the distribution system from the water treatment plant to the exit from the reservoir was found. The richness of the bacterial population was reduced from the water treatment plant to the reservoir (from 336 to 165 OTUs for water samples leaving the reservoir and from 947 to 275 for biofilm samples in the network). Several OTUs belonging to pathogenic genera were detected in our samples, mostly in the biofilm samples, thus suggesting that the biofilms may be an important source of bacteria during water distribution to the consumers.

Style APA, Harvard, Vancouver, ISO itp.

47

Hussain, Malik Asif. "An investigation of the impact of bacterial diversity, pathogenic determinants and biofilms on chronic wounds". Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/110339/2/Malik_Asif_Hussain_Thesis.pdf.

Pełny tekst źródła

Streszczenie:

The researcher investigated the abundance and diversity of bacteria in chronic wounds. Chronic wounds are a significant public health burden and associated with complex polymicrobial communities. Bacterial colonization has been hypothesized to be one of the main underlying causes of chronic wounds and leads to detrimental effects on wound healing. Next-generation sequencing technologies were utilized to identify possible bacterial biomarkers to predict wound healing trajectory. Overall, bacterial bioburden and their molecular characteristics were found to be associated with and predictive of poor wound healing outcomes. This research has been presented at conferences and in publications.

Style APA, Harvard, Vancouver, ISO itp.

48

Horn, Matthias. "Molecular ecology of free-living amoebae and their bacterial endosymbionts diversity and interactions /". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963285157.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

49

Grove, Jason Andrew. "Assessment of the Potential Functional Diversity of the Bacterial Community in a Biofilter". Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/850.

Pełny tekst źródła

Streszczenie:

A biofilter removes biodegradable contaminants from air by passing it through a biologically-active packed bed. The microorganism community is of fundamental interest but has been the focus of few studies. This work is an investigation of the bacterial community based on the potential functional diversity of the community.

A number of experiments were performed in laboratory-scale biofilters using ethanol as a model contaminant. All biofilters were able to remove the ethanol with elimination capacities in the range 80 to 200gVOCm^-3h^-1; these values are comparable with published literature. Natural organic media (peat or compost) was used as packing.

The potential functional diversity of the community was assessed by Community-Level Physiological Profiling (CLPP) using sole-Carbon Source Utilisation Profile (CSUP). Community samples were used to inoculate Biolog EcoPlates^TM: microplates containing a selection of 31 different carbon-substrates and an indicator dye responding to bacterial growth. This technique was found to be sensitive to changes in the community structure over time and location.

Results showed that the community in samples taken close together (over a scale of a few centimetres) are similar and that relatively small media samples (0. 5 to 1 g) provide reproducible information. A study of a single biofilter indicated stratification of the community occurring with the community near the inlet diverging from that near the middle and outlet of the unit; this is attributed to the ethanol being degraded in the upper part of the column and the lower part of the column not being subjected to ethanol loading. In a study of two units at a higher loading rate, stratification was not observed over a period of weeks; it is suggested that the stratification may develop over this timescale as a result of the presence or absence of the Volatile Organic Compound (VOC) and not due to differences in concentration.

An acclimation period of 7 to 10 days was observed before near-complete removal of ethanol was attained. Monitoring of the community suggested a subsequent shift in diversity. It is suggested that the initial acclimation period is due to biofilm formation and the subsequent shift in community diversity is due to re-organisation of the community as species specialise. In a portion of the biofilter with minimal ethanol exposure, a sudden shift in community is observed after a period of some weeks. This may reflect changes as a result of starvation and indicates that periods of shut-down (when the biofilter is not loaded) may affect the community.

Two studies of biofilters operating in parallel were carried out. The first provided evidence of a divergence in the communities over a period of two weeks. In the second, communities in the two units underwent changes over time but observations from both units at any one time were similar. This demonstrates that biofilters set-up and operated in a similar manner may maintain similar communities but that this is not necessarily the case. This has implications for the reproducibility of laboratory experiments and for the variation of community structure with horizontal position in industrial units.

Style APA, Harvard, Vancouver, ISO itp.

50

Mahmoud, Huda Mahmoud Abdullah. "Structural and functional diversity of epilithic bacterial communities in streams : effects of pollution". Thesis, University of Hull, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271992.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

Rozprawy doktorskie na temat „Bacterial diversity”

Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych