1,720,969 research outputs found
The effect of ambient air pollution on bacterial and fungal communities in the phylloplane of Hedera helix and their implications in degradation of airborne pollutants
No full textAmbient air pollution is one of the serious problems our world is currently facing,
exerting wide-ranging and deleterious effects on the environment and on our
health. It is most pronounced in high-traffic environments such as urban areas
where substantial quantities of airborne pollutants, including particulate matter
(PM) and volatile organic compounds (VOCs), are generated. While technological
improvements and stricter emission regulations have contributed to a decrease in
traffic-related emissions of airborne pollutants, current emission abatement
strategies are not sufficient to cope with the global threat of air pollution and there
remains a strong demand for effective solutions to be developed. This doctoral
research contributes to meet this demand by exploring the use of plants and their
associated microorganisms to detoxify airborne pollutants. We provide an indepth analysis of the phylloplane microbiome associated with Hedera helix (ivy),
an evergreen plant known for its hardiness and climbing ability, including a
comprehensive study of the influence of ambient air pollution on the leaf
communities. We present a thorough taxonomic description of the microbial
communities living on H. helix leaves, which we show to be dominated by the
phyla Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Ascomycota, and
Basidiomycota, and the genera Hymenobacter, Sphingomonas, Pseudomonas,
Methylobacterium, Massilia, Pantoea, Cryptococcus, Davidiella, Mycosphaerella,
Sporobolomyces, Kabatiella, and Rhodotorula. We also evaluated the culturability
of this habitat using five different growth media, and present a collection of
microbial phylloplane isolates underrepresented in current databases, including
the characterization of PGP profiles, trace metal resistance, and pollutant
degradation potential. In a pilot phase, we started with investigating if ambient
air pollution has the potential to influence the structure and function of bacterial
communities in the phylloplane of H. helix. Our results indicated that ambient air pollution increases the metabolic versatility of microbial leaf communities and the
prevalence of bacterial functional traits affiliated to an increased fitness in a
polluted environment. Continuing on these results, we designed a field study with
a duration of two years where we sampled a total of 4,320 H. helix leaves at six
locations exposed to different ambient air pollution conditions. We performed
eight sampling events, one in every season, from autumn 2017 until summer
2019. Daily we monitored ambient black carbon (BC), PM2.5, PM10, nitrogen
dioxide, and ozone concentrations and found that ambient air pollution led to a 2-
to 7-fold increase of BC that was present on the sampled leaves, the phylloplane
BC load. Our results further indicated this phylloplane BC load strongly correlates
with the diversity of bacterial and fungal H. helix leaf communities, impacting this
diversity even more than seasonal effects and suggesting that ambient air
pollution significantly contributes to the shaping of bacterial and fungal ivy leaf
communities. Further, we focus on the phylloplane-associated Microbacteriaceae
genera Curtobacterium, Rathayibacter, Frigoribacterium, and Frondihabitans in a
genus-level pangenomic approach and propose updated phylogenies. We show
that phylloplane bacteria have primarily invested in genomic features related to
interactions with their environment, among which osmoregulation, ion transport,
uptake and metabolism of various nutrients, and signal transduction, reflecting
key adaptations to bacterial life in the harsh conditions of the phylloplane. Lastly,
we present six phylloplane microorganisms that were isolated from an air-polluted
environment and able to metabolize diesel fuel. Three of these isolates, Bacillus
licheniformis VSD4, Pseudomonas sp. VS38, and Rhodotorula sp. VS67, also
degraded the fossil fuel-related VOCs benzene, toluene, and/or xylene (BTX), and
constitute promising candidates as inoculants towards (phyllo)remediation
applications
The effect of ambient air pollution on bacterial and fungal communities in the phylloplane of Hedera helix and their implications in degradation of airborne pollutants
No full textAmbient air pollution is one of the serious problems our world is currently facing,
exerting wide-ranging and deleterious effects on the environment and on our
health. It is most pronounced in high-traffic environments such as urban areas
where substantial quantities of airborne pollutants, including particulate matter
(PM) and volatile organic compounds (VOCs), are generated. While technological
improvements and stricter emission regulations have contributed to a decrease in
traffic-related emissions of airborne pollutants, current emission abatement
strategies are not sufficient to cope with the global threat of air pollution and there
remains a strong demand for effective solutions to be developed. This doctoral
research contributes to meet this demand by exploring the use of plants and their
associated microorganisms to detoxify airborne pollutants. We provide an indepth analysis of the phylloplane microbiome associated with Hedera helix (ivy),
an evergreen plant known for its hardiness and climbing ability, including a
comprehensive study of the influence of ambient air pollution on the leaf
communities. We present a thorough taxonomic description of the microbial
communities living on H. helix leaves, which we show to be dominated by the
phyla Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Ascomycota, and
Basidiomycota, and the genera Hymenobacter, Sphingomonas, Pseudomonas,
Methylobacterium, Massilia, Pantoea, Cryptococcus, Davidiella, Mycosphaerella,
Sporobolomyces, Kabatiella, and Rhodotorula. We also evaluated the culturability
of this habitat using five different growth media, and present a collection of
microbial phylloplane isolates underrepresented in current databases, including
the characterization of PGP profiles, trace metal resistance, and pollutant
degradation potential. In a pilot phase, we started with investigating if ambient
air pollution has the potential to influence the structure and function of bacterial
communities in the phylloplane of H. helix. Our results indicated that ambient air pollution increases the metabolic versatility of microbial leaf communities and the
prevalence of bacterial functional traits affiliated to an increased fitness in a
polluted environment. Continuing on these results, we designed a field study with
a duration of two years where we sampled a total of 4,320 H. helix leaves at six
locations exposed to different ambient air pollution conditions. We performed
eight sampling events, one in every season, from autumn 2017 until summer
2019. Daily we monitored ambient black carbon (BC), PM2.5, PM10, nitrogen
dioxide, and ozone concentrations and found that ambient air pollution led to a 2-
to 7-fold increase of BC that was present on the sampled leaves, the phylloplane
BC load. Our results further indicated this phylloplane BC load strongly correlates
with the diversity of bacterial and fungal H. helix leaf communities, impacting this
diversity even more than seasonal effects and suggesting that ambient air
pollution significantly contributes to the shaping of bacterial and fungal ivy leaf
communities. Further, we focus on the phylloplane-associated Microbacteriaceae
genera Curtobacterium, Rathayibacter, Frigoribacterium, and Frondihabitans in a
genus-level pangenomic approach and propose updated phylogenies. We show
that phylloplane bacteria have primarily invested in genomic features related to
interactions with their environment, among which osmoregulation, ion transport,
uptake and metabolism of various nutrients, and signal transduction, reflecting
key adaptations to bacterial life in the harsh conditions of the phylloplane. Lastly,
we present six phylloplane microorganisms that were isolated from an air-polluted
environment and able to metabolize diesel fuel. Three of these isolates, Bacillus
licheniformis VSD4, Pseudomonas sp. VS38, and Rhodotorula sp. VS67, also
degraded the fossil fuel-related VOCs benzene, toluene, and/or xylene (BTX), and
constitute promising candidates as inoculants towards (phyllo)remediation
applications
Diversity and plant growth-promoting potential of (un)culturable bacteria in the Hedera helix phylloplane
No full textBackground: A diverse community of microbes naturally exists on the phylloplane, the surface of leaves. It is one of the most prevalent microbial habitats on earth and bacteria are the most abundant members, living in communities that are highly dynamic. Today, one of the key challenges for microbiologists is to develop strategies to culture the vast diversity of microorganisms that have been detected in metagenomic surveys.
Results: We isolated bacteria from the phylloplane of Hedera helix (common ivy), a widespread evergreen, using five growth media: Luria–Bertani (LB), LB01, yeast extract–mannitol (YMA), yeast extract–flour (YFlour), and YEx. We also included a comparison with the uncultured phylloplane, which we showed to be dominated by Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes. Inter-sample (beta) diversity shifted from LB and LB01 containing the highest amount of resources to YEx, YMA, and YFlour which are more selective. All growth media equally favoured Actinobacteria and Gammaproteobacteria, whereas Bacteroidetes could only be found on LB01, YEx, and YMA. LB and LB01 favoured Firmicutes and YFlour was most selective for Betaproteobacteria. At the genus level, LB favoured the growth of Bacillus and Stenotrophomonas, while YFlour was most selective for Burkholderia and Curtobacterium. The in vitro plant growth promotion (PGP) profile of 200 isolates obtained in this study indicates that previously uncultured bacteria from the phylloplane may have potential applications in phytoremediation and other plant-based biotechnologies.
Conclusions: This study gives first insights into the total bacterial community of the H. helix phylloplane, including an evaluation of its culturability using five different growth media. We further provide a collection of 200 bacterial isolates underrepresented in current databases, including the characterization of PGP profiles. Here we highlight the potential of simple strategies to obtain higher microbial diversity from environmental samples and the use of high-throughput sequencing to guide isolate selection from a variety of growth media.Funding
This work was supported by the Hasselt University Methusalem project 08M03VGRJ, by the project G0D0916N (“Plant–microbe associations to reduce particulate matter concentration and toxicity in urban areas: a multidisciplinary approach”) financed by the Research Foundation – Flanders (FWO) and by a personal grant of VS provided by the Research Foundation – Flanders (FWO). The funding bodies had no role in the design of the study and collection, analysis, interpretation of data, or manuscript preparation.
Acknowledgements
We thank Prof. Jonathan Van Hamme for proofreading the language in this manuscript. We thank the VSC (Flemish Supercomputer Center), funded by the Research Foundation – Flanders (FWO) and the Flemish Government – department EWI for providing the computational resources and services used in this work
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
