scholarly journals Effects of Systemic Pesticides Imidacloprid and Metalaxyl on the Phyllosphere of Pepper Plants

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Constantinos Moulas ◽  
Christos Petsoulas ◽  
Konstantina Rousidou ◽  
Chiara Perruchon ◽  
Panagiotis Karas ◽  
...  
Keyword(s):  
Microbial Community ◽  
Bacterial Community ◽  
Fungal Community ◽  
Bacterial Communities ◽  
Potential Role ◽  
Plant Foliage ◽  
The Impact ◽  
Impact Of Pesticides ◽  
Pepper Plants

Microbes inhabiting the phyllosphere of crops are exposed to pesticides applied either directly onto plant foliage or indirectly through soil. Although, phyllosphere microbiology has been rapidly evolving, little is still known regarding the impact of pesticides on the epiphytic microbial community and especially on fungi. We determined the impact of two systemic pesticides (metalaxyl and imidacloprid), applied either on foliage or through soil, on the epiphytic fungal and bacterial communities via DGGE and cloning. Both pesticides induced mild effects on the fungal and the bacterial communities. The only exception was the foliage application of imidacloprid which showed a more prominent effect on the fungal community. Cloning showed that the fungal community was dominated by putative plant pathogenic ascomycetes (Erysiphaceae andCladosporium), while a few basidiomycetes were also present. The former ribotypes were not affected by pesticides application, while selected yeasts (Cryptococcus) were stimulated by the application of imidacloprid suggesting a potential role in its degradation. A less diverse bacterial community was identified in pepper plants. Metalaxyl stimulated an Enterobacteriaceae clone which is an indication of the involvement of members of this family in fungicide degradation. Further studies will focus on the isolation of epiphytic microbes which appear to be stimulated by pesticides application.

scholarly journals Ecological networks reveal contrasting patterns of bacterial and fungal communities in glacier-fed streams in Central Asia

2019 ◽  
Author(s):  
Ze Ren ◽  
Hongkai Gao
Keyword(s):  
Bacterial Community ◽  
Microbial Communities ◽  
Central Asia ◽  
Fungal Community ◽  
Bacterial Communities ◽  
Beta Diversity ◽  
Hydrological Modeling ◽  
Alpha Diversity ◽  
Environmental Variation ◽  
Fungal Communities

Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especially considering both bacterial and fungal communities. A focus on beta diversity can provide insights into the mechanisms driving community changes associated to large environmental fluctuations and disturbances, such as in glacier-fed streams. Moreover, modularity of co-occurrence networks can reveal more ecological and evolutionary properties of microbial communities beyond taxonomic groups. Here, integrating beta diversity and co-occurrence approach, we explored the network topology and modularity of the bacterial and fungal communities with consideration of environmental variation in glacier-fed streams in Central Asia. Combining results from hydrological modeling and normalized difference of vegetation index, this study highlighted that hydrological variables and vegetation status are major variables determining the environmental heterogeneity of glacier-fed streams. Bacterial communities formed a more complex and connected network, while the fungal communities formed a more clustered network. Moreover, the strong interrelations among the taxonomic dissimilarities of bacterial community and modules suggest they had common processes in driving diversity and taxonomic compositions across the heterogeneous environment. In contrast, fungal community and modules generally showed distinct driving processes to each other. Moreover, bacterial and fungal communities also had different driving processes. Furthermore, the variation of bacterial community and modules were strongly correlated with hydrological properties and vegetation status but not with nutrients, while fungal community and modules (except one module) were not associated with environmental variation. Our results suggest that bacterial and fungal communities had distinct mechanisms in structuring microbial networks, and environmental variation had strong influences on bacterial communities but not on fungal communities. The fungal communities have unique assembly mechanisms and physiological properties which might lead to their insensitive responses to environmental variations compared to bacterial communities. Overall, beyond alpha diversity in previous studies, these results add our knowledge that bacterial and fungal communities have contrasting assembly mechanisms and respond differently to environmental variation in glacier-fed streams.

scholarly journals Ecological networks reveal contrasting patterns of bacterial and fungal communities in glacier-fed streams in Central Asia

2019 ◽  
Author(s):  
Ze Ren ◽  
Hongkai Gao
Keyword(s):  
Bacterial Community ◽  
Microbial Communities ◽  
Central Asia ◽  
Fungal Community ◽  
Bacterial Communities ◽  
Beta Diversity ◽  
Hydrological Modeling ◽  
Alpha Diversity ◽  
Environmental Variation ◽  
Fungal Communities

Bacterial and fungal communities in biofilms are important components in driving biogeochemical processes in stream ecosystems. Previous studies have well documented the patterns of bacterial alpha diversity in stream biofilms in glacier-fed streams, where, however, beta diversity of the microbial communities has received much less attention especially considering both bacterial and fungal communities. A focus on beta diversity can provide insights into the mechanisms driving community changes associated to large environmental fluctuations and disturbances, such as in glacier-fed streams. Moreover, modularity of co-occurrence networks can reveal more ecological and evolutionary properties of microbial communities beyond taxonomic groups. Here, integrating beta diversity and co-occurrence approach, we explored the network topology and modularity of the bacterial and fungal communities with consideration of environmental variation in glacier-fed streams in Central Asia. Combining results from hydrological modeling and normalized difference of vegetation index, this study highlighted that hydrological variables and vegetation status are major variables determining the environmental heterogeneity of glacier-fed streams. Bacterial communities formed a more complex and connected network, while the fungal communities formed a more clustered network. Moreover, the strong interrelations among the taxonomic dissimilarities of bacterial community and modules suggest they had common processes in driving diversity and taxonomic compositions across the heterogeneous environment. In contrast, fungal community and modules generally showed distinct driving processes to each other. Moreover, bacterial and fungal communities also had different driving processes. Furthermore, the variation of bacterial community and modules were strongly correlated with hydrological properties and vegetation status but not with nutrients, while fungal community and modules (except one module) were not associated with environmental variation. Our results suggest that bacterial and fungal communities had distinct mechanisms in structuring microbial networks, and environmental variation had strong influences on bacterial communities but not on fungal communities. The fungal communities have unique assembly mechanisms and physiological properties which might lead to their insensitive responses to environmental variations compared to bacterial communities. Overall, beyond alpha diversity in previous studies, these results add our knowledge that bacterial and fungal communities have contrasting assembly mechanisms and respond differently to environmental variation in glacier-fed streams.

Bacterial communities of the rhizosphere and endorhiza associated with field-grown cucumber plants inoculated with a plant growth-promoting rhizobacterium or its genetically modified derivative

1997 ◽  
Vol 43 (4) ◽  
pp. 344-353 ◽  
Author(s):  
W. F. Mahaffee ◽  
J. W. Kloepper
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Genetically Modified ◽  
Acid Methyl Ester ◽  
Wild Type ◽  
Natural Ecosystems ◽  
Genus Level ◽  
Plant Growth Promoting ◽  
The Impact

The future use of genetically modified microorganisms in the environment will be dependent on the ability to assess potential or theoretical risks associated with their introduction into natural ecosystems. To assess potential risks, several ecological parameters must be examined, including the impact of the introduced genetically modified organism on the microbial communities associated with the environment into which the introduction will occur. A 2-year field study was established to examine whether the indigenous bacterial communities of the rhizosphere and endorhiza (internal root tissues) were affected differently by the introduction of an unaltered wild type and its genetically modified derivative. Treatments consisted of the wild-type strain Pseudomonas fluorescens 89B-27 and a bioluminescent derivative GEM-8 (89B-27::Tn4431). Cucumber root or seed samples were taken 0, 7, 14, 21, 35, and 70 days after planting (DAP) in 1994 and 0, 7, 14, 28, 42, and 70 DAP in 1995. Samples were processed to examine the bacterial communities of both the rhizosphere and endorhiza. Over 7200 bacterial colonies were isolated from the rhizosphere and endorhiza and identified using the Sherlock System (Microbial ID, Inc.) for fatty acid methyl ester analysis. Community structure at the genus level was assessed using genera richness and Hill's diversity numbers, N1 and N2. The aerobic–heterotrophic bacterial community structure at the genus level did not significantly vary between treatments but did differ temporally. The data indicate that the introduction of the genetically modified derivative of 89B-27 did not pose a greater environmental risk than its unaltered wild type with respect to aerobic–heterotrophic bacterial community structure.Key words: diversity, ecology, PGPR, Pseudomonas, root colonizaton, GEM.

scholarly journals Increase in Bacterial Community Diversity in Subsurface Aquifers Receiving Livestock Wastewater Input

2000 ◽  
Vol 66 (3) ◽  
pp. 956-965 ◽  
Author(s):  
Jang-Cheon Cho ◽  
Sang-Jong Kim
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Community Diversity ◽  
Similarity Coefficients ◽  
Livestock Wastewater ◽  
Contaminated Aquifer ◽  
Bacterial Community Diversity ◽  
Rdna Sequences ◽  
Wastewater Samples ◽  
The Impact

ABSTRACT Despite intensive studies of microbial-community diversity, the questions of which kinds of microbial populations are associated with changes in community diversity have not yet been fully solved by molecular approaches. In this study, to investigate the impact of livestock wastewater on changes in the bacterial communities in groundwater, bacterial communities in subsurface aquifers were analyzed by characterizing their 16S rDNA sequences. The similarity coefficients of restriction fragment length polymorphism (RFLP) patterns of the cloned 16S ribosomal DNAs showed that the bacterial communities in livestock wastewater samples were more closely related to those in contaminated aquifer samples. In addition, calculations of community diversity clearly showed that bacterial communities in the livestock wastewater and the contaminated aquifer were much more diverse than those in the uncontaminated aquifer. Thus, the increase in bacterial-community diversity in the contaminated aquifer was assumed to be due to the infiltration of livestock wastewater, containing high concentrations of diverse microbial flora, into the aquifer. Phylogenetic analysis of the sequences from a subset of the RFLP patterns showed that the Cytophaga-Flexibacter-Bacteroidesand low-G+C gram-positive groups originating from livestock wastewater were responsible for the change in the bacterial community in groundwater. This was evidenced by the occurrence of rumen-related sequences not only in the livestock wastewater samples but also in the contaminated-groundwater samples. Rumen-related sequences, therefore, can be used as indicator sequences for fecal contamination of groundwater, particularly from livestock.

scholarly journals Effects of shade stress on morphophysiology and rhizosphere soil bacterial communities of two contrasting shade-tolerant turfgrasses

2019 ◽  
Author(s):  
Juanjuan Fu ◽  
Yilan Luo ◽  
Pengyue Sun ◽  
Jinzhu Gao ◽  
Donghao Zhao ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Plant Growth ◽  
Bacterial Communities ◽  
Shade Tolerance ◽  
Rhizosphere Soil ◽  
Photosynthetic Capacity ◽  
Bacterial Community Composition ◽  
Soil Microbial Communities ◽  
Soil Bacterial ◽  
The Impact

Abstract Background: Shade presents one of the major abiotic limitations for turfgrass growth. Shade influences plant growth and alters plant metabolism, yet little is known about how shade affects the structure of rhizosphere soil microbial communities and the role of soil microorganisms in plant shade responses. In this study, a glasshouse experiment was conducted to examine the impact of shade stress on the growth and photosynthetic capacity of two contrasting shade-tolerant turfgrasses, shade-tolerant dwarf lilyturf (Ophiopogon japonicus, OJ) and shade-intolerant perennial turf-type ryegrass (Lolium perenne, LP). We also examined soil-plant feedback effects on shade tolerance in the two turfgrass genotypes. Bacterial community composition was assayed using high-throughput sequencing. Results: Our physiochemical data showed that under shade stress, OJ maintained higher photosynthetic capacity and root growth, thus OJ was found to be more shade-tolerant than LP. Shade-intolerant LP responded better to both shade and soil microbes than shade-tolerant OJ. Shade and live soil decreased LP growth but increased biomass allocation to shoots in the live soil. The plant shade response index of LP is higher in the live soil than sterile soil, driven by weakened soil-plant feedback under shade stress. In contrast, there was no difference in these values for OJ under similar shade and soil treatments. Illumina sequencing data revealed that shade stress had little impact on the diversity of the OJ and LP’s bacterial communities, but instead impacted the composition of bacterial communities. The bacterial communities were mostly composed of Proteobacteria and Acidobacteria in OJ soil. Further pairwise fitting analysis showed that a positive correlation of shade-tolerance in two turfgrasses and their bacterial community compositions. Several soil properties (NO3--N, NH4+-N, AK) showed a tight coupling with several major bacterial communities under shade stress, indicating that they are important drivers determining bacterial community structures. Moreover, OJ shared core bacterial taxa known to promote plant growth and confer tolerance to shade stress, which suggests common principles underpinning OJ-microbe interactions. Conclusion: Plant shade tolerance is mediated by soil-plant feedback and shade-induced changes in rhizosphere soil bacterial community structure in OJ and LP plants.

scholarly journals 16S rRNA metagenomic analysis of the bacterial community associated with turf grass seeds from low moisture and high moisture climates

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8417 ◽  
Author(s):  
Qiang Chen ◽  
William A. Meyer ◽  
Qiuwei Zhang ◽  
James F. White
Keyword(s):  
Microbial Community ◽  
Seed Germination ◽  
Bacterial Community ◽  
16S Rrna ◽  
Seedling Growth ◽  
Bacterial Communities ◽  
Metagenomic Analysis ◽  
High Moisture ◽  
Core Microbiome ◽  
Dry Climates

Turfgrass investigators have observed that plantings of grass seeds produced in moist climates produce seedling stands that show greater stand evenness with reduced disease compared to those grown from seeds produced in dry climates. Grass seeds carry microbes on their surfaces that become endophytic in seedlings and promote seedling growth. We hypothesize that incomplete development of the microbiome associated with the surface of seeds produced in dry climates reduces the performance of seeds. Little is known about the influence of moisture on the structure of this microbial community. We conducted metagenomic analysis of the bacterial communities associated with seeds of three turf species (Festuca rubra, Lolium arundinacea, and Lolium perenne) from low moisture (LM) and high moisture (HM) climates. The bacterial communities were characterized by Illumina high-throughput sequencing of 16S rRNA V3–V4 regions. We performed seed germination tests and analyzed the correlations between the abundance of different bacterial groups and seed germination at different taxonomy ranks. Climate appeared to structure the bacterial communities associated with seeds. LM seeds vectored mainly Proteobacteria (89%). HM seeds vectored a denser and more diverse bacterial community that included Proteobacteria (50%) and Bacteroides (39%). At the genus level, Pedobacter (20%), Sphingomonas (13%), Massilia (12%), Pantoea (12%) and Pseudomonas (11%) were the major genera in the bacterial communities regardless of climate conditions. Massilia, Pantoea and Pseudomonas dominated LM seeds, while Pedobacter and Sphingomonas dominated HM seeds. The species of turf seeds did not appear to influence bacterial community composition. The seeds of the three turf species showed a core microbiome consisting of 27 genera from phyla Actinobacteria, Bacteroidetes, Patescibacteria and Proteobacteria. Differences in seed-vectored microbes, in terms of diversity and density between high and LM climates, may result from effects of moisture level on the colonization of microbes and the development of microbe community on seed surface tissues (adherent paleas and lemmas). The greater diversity and density of seed vectored microbes in HM climates may benefit seedlings by helping them tolerate stress and fight disease organisms, but this dense microbial community may also compete with seedlings for nutrients, slowing or modulating seed germination and seedling growth.

scholarly journals Metagenomics reveals diet-specific specialization of bacterial communities in fungus gardens of grass- and dicot-cutter ants

2018 ◽  
Author(s):  
Lily Khadempour ◽  
Huan Fan ◽  
Ken Keefover-Ring ◽  
Camila Carlos ◽  
Nilson S. Nagamoto ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Potential Role ◽  
Sequence Data ◽  
Bacterial Community Composition ◽  
Fungus Garden ◽  
Functional Profiles ◽  
Ant Fungus

AbstractLeaf-cutter ants in the genusAttaare dominant herbivores in the Neotropics. While most species ofAttacut dicots to incorporate into their fungus gardens, some species specialize on grasses. Here we examine the bacterial community associated with the fungus gardens of grass- and dicot-cutter ants to examine how changes in substrate input affect the bacterial community. We sequenced the metagenomes of 12Attafungus gardens, across four species of ants, with a total of 5.316 Gbp of sequence data. We show significant differences in the fungus garden bacterial community composition between dicot- and grass-cutter ants, with grass-cutter ants having lower diversity. Reflecting this difference in community composition, the bacterial functional profiles between the fungus gardens are significantly different. Specifically, grass-cutter ant fungus garden metagenomes are particularly enriched for genes responsible for amino acid, siderophore, and terpenoid biosynthesis while dicot-cutter ant fungus gardens metagenomes are enriched in genes involved in membrane transport. These differences in bacterial community composition and functional capacity show that different substrate inputs matter for fungus garden bacteria, and sheds light on the potential role of bacteria in mediating the ants’ transition to the use of a novel substrate.

scholarly journals Impact of long-term industrial contamination on the bacterial communities in urban river sediments

2020 ◽  
Author(s):  
Lei Zhang ◽  
Demei Tu ◽  
Xingchen Li ◽  
Wenxuan Lu ◽  
Jing Li
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Industrial Pollution ◽  
River Sediments ◽  
Urban River ◽  
Industrial Contamination ◽  
Different Types

Abstract Background: The contamination of the aquatic environment of urban rivers with industrial wastewater has affected the abiotic conditions and biological activities of the trophic levels of the ecosystem, particularly sediments. However, most current research about microorganism in urban aquatic environments has focused on indicator bacteria related to feces and organic pollution. Meanwhile, they ignored the interactions among microorganisms. To deeply understand the impact of industrial contamination on microbial community, we study the bacterial community structure and diversity in river sediments under the influence of different types of industrial pollution by Illumina MiSeq high-throughput sequencing technology and conduct a more detailed analysis of microbial community structure through co-occurrence networks.Results: The overall community composition and abundance of individual bacterial groups differed between samples. In addition, redundancy analysis indicated that the structure of the bacterial community in river sediments was influenced by a variety of environmental factors. TN, TP, TOC and metals (Cu, Zn and Cd) were the most important driving factors that determined the bacterial community in urban river sediments (P <0.01). According to PICRUSt analysis, the bacterial communities in different locations had similar overall functional profiles. It is worth noting that the 15 functional genes related to xenobiotics biodegradation and metabolism were the most abundant in the same location. The non-random assembly patterns of bacterial composition in different types of industrially polluted sediments were determined by a co-occurrence network. Environmental conditions resulting from different industrial pollutants may play an important role in determining their co-occurrence patterns of these bacterial taxa. Among them, the bacterial taxa involved in carbon and nitrogen cycles in module I were relatively abundant, and the bacterial taxa in module II were involved in the repair of metal pollution.Conclusions: Our data indicate that long-term potential interactions between different types of industrial pollution and taxa collectively affect the structure of the bacterial community in urban river sediments.

scholarly journals The leaf bacterial microbiota of female and male kiwifruit plants in distinct seasons: assessing the impact of Pseudomonas syringae pv. actinidiae

2021 ◽  
Author(s):  
Aitana Ares ◽  
Joana Pereira ◽  
Eva Garcia ◽  
Joana Costa ◽  
Igor Tiago
Keyword(s):  
Bacterial Community ◽  
Pseudomonas Syringae ◽  
Relative Abundance ◽  
Bacterial Communities ◽  
Defense Mechanisms ◽  
Abiotic Factors ◽  
Illumina Miseq ◽  
Rrna Gene ◽  
Sequencing Platform ◽  
The Impact

The pandemic Pseudomonas syringae pv. actinidiae (Psa) has been compromising the production of the kiwifruit industry in major producing countries. Abiotic factors and plant gender are known to influence the disease outcome. To better understand their impact, we have determined the diversity of the leafs bacterial communities using the V5-V6 region of the 16S rRNA gene amplicon on the Illumina MiSeq sequencing platform. Healthy and diseased female and male kiwifruit plants were analyzed in two consecutive seasons: spring and autumn. This work describes whether the season, plant gender and the presence of Psa can affect the leaves bacterial community. Fifty bacterial operational taxonomic units (OTUs) were identified and assigned to five phyla distributed by 14 different families and 23 genera. The leaves of healthy female and male kiwi plants share most of the identified bacterial populations, that undergoes major seasonal changes. In both cases a substantial increase of the relative abundance of genus Methylobacterium is observed in autumn. The presence of Psa induced profound changes on leaves bacterial communities structure translated into a reduction in the relative abundance of previously dominant genera that had been found in healthy plants, namely Hymenobacter, Sphingomonas and Massilia. The impact of Psa was less pronounced in the bacterial community structure of male plants in both seasons. Some of the naturally occurring genera have the potential to act as an antagonist or as enhancers of the defense mechanisms paving the way for environmentally friendly and sustainable disease control.

scholarly journals Bacteria as Emerging Indicators of Soil Condition

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Syrie M. Hermans ◽  
Hannah L. Buckley ◽  
Bradley S. Case ◽  
Fiona Curran-Cournane ◽  
Matthew Taylor ◽  
...  
Keyword(s):  
Land Use ◽  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Soil Condition ◽  
Soil Types ◽  
Anthropogenic Activity ◽  
Content Type ◽  
Soil Ecosystems ◽  
The Impact

ABSTRACT Bacterial communities are important for the health and productivity of soil ecosystems and have great potential as novel indicators of environmental perturbations. To assess how they are affected by anthropogenic activity and to determine their ability to provide alternative metrics of environmental health, we sought to define which soil variables bacteria respond to across multiple soil types and land uses. We determined, through 16S rRNA gene amplicon sequencing, the composition of bacterial communities in soil samples from 110 natural or human-impacted sites, located up to 300 km apart. Overall, soil bacterial communities varied more in response to changing soil environments than in response to changes in climate or increasing geographic distance. We identified strong correlations between the relative abundances of members of Pirellulaceae and soil pH, members of Gaiellaceae and carbon-to-nitrogen ratios, members of Bradyrhizobium and the levels of Olsen P (a measure of plant available phosphorus), and members of Chitinophagaceae and aluminum concentrations. These relationships between specific soil attributes and individual soil taxa not only highlight ecological characteristics of these organisms but also demonstrate the ability of key bacterial taxonomic groups to reflect the impact of specific anthropogenic activities, even in comparisons of samples across large geographic areas and diverse soil types. Overall, we provide strong evidence that there is scope to use relative taxon abundances as biological indicators of soil condition. IMPORTANCE The impact of land use change and management on soil microbial community composition remains poorly understood. Therefore, we explored the relationship between a wide range of soil factors and soil bacterial community composition. We included variables related to anthropogenic activity and collected samples across a large spatial scale to interrogate the complex relationships between various bacterial community attributes and soil condition. We provide evidence of strong relationships between individual taxa and specific soil attributes even across large spatial scales and soil and land use types. Collectively, we were able to demonstrate the largely untapped potential of microorganisms to indicate the condition of soil and thereby influence the way that we monitor the effects of anthropogenic activity on soil ecosystems into the future.

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