scholarly journals Characterising the benthic Phormidium autumnale-dominated biofilm community and anatoxin production throughout biofilm succession

2021 ◽  
Author(s):  
◽  
Katie Anne Brasell
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Molecular Techniques ◽  
Algal Community ◽  
Microbial Succession ◽  
Microbial Composition ◽  
Community Shifts ◽  
Biofilm Development ◽  
Biofilm Community ◽  
Over Time

<p>There has been an increase in the prevalence and intensity of Phormidium autumnale-dominated benthic blooms in New Zealand over the last decade. This species produces the potent neurotoxins Anatoxin-a, Homoanatoxin-a and their derivatives, and consumption of P. autumnale biofilms has led to over 70 dog deaths since 2005. The mechanisms regulating the dominance and toxicity of P. autumnale are still unclear, as these blooms can reach high biomass in low nutrient conditions. Benthic biofilms are composed of multiple taxa and usually harbor a complex community of bacteria and other microbes, which can change over time and interact to facilitate biofilm development and metabolic processing. Prior to this thesis, the microbial composition of P. autumnale-dominated biofilms was unknown. This study provides insights into the relationships of this neurotoxic cyanobacterium with microbial components of the biofilm community.  Benthic biofilms were sampled every two to four days for 32 days from three sites in the Hutt River (Wellington) following a high flow event. A combination of microscopy and molecular techniques (bacterial ARISA and Illumina™ sequencing) were used to identify the micro-algal and bacterial components of the biofilm throughout its development. Variation in total anatoxin production was measured using LC-MS and changes in toxic P. autumnale cell numbers were quantified using QPCR. A suite of environmental variables (point velocity, depth, flow, conductivity, temperature and nutrients) were also monitored throughout the study period.  Three distinct phases of microbial succession were identified (early, mid and late) using non-metric multidimensional cluster analyses. The micro-algal community composition (including P. autumnale) shifted from early to mid-phase ca. 16 days after the flushing flow and from mid to late phase at ca. day 30. The ARISA and Illumina™ sequencing showed the bacterial community shifts occurred ca. 4 and 9 days before the respective micro-algal community shifts. These analyses indicate a close coupling of the micro-algal and bacterial communities and may suggest bacterial driven succession. However, bacteria are likely to depend on micro-algal by-products for nutrition from the mid-phases onward and assessment of the metabolic processes occurring within the biofilms is needed to clarify this.  Phormidium autumnale was dominant in the biofilm from an early stage in development and grew exponentially despite an influx of diatoms at day 20. None of the environmental parameters measured could explain the temporal variation in micro-algal and bacterial communities, which suggested that intrinsic rather than extrinsic factors were more important in regulating succession. This further supports the hypothesis that biofilm microbes may facilitate P. autumnale dominance.  There was a significant variation in anatoxins per cell over time (p = 0.034). Production of anatoxins was greatest in the mid-phase of succession (208 fg cell⁻¹), coinciding with an increase in diatom biomass, which could implicate anatoxins as allelopathic chemicals that alleviate the effects of competition on P. autumnale. Changes in proportions of the different anatoxin variants produced over time also aligned with the three successional phases in both the micro-algal and bacterial communities, providing further evidence of a relationship between anatoxin production and microbial biofilm components.  Bacterial taxa of the Alphaproteobacteria were dominant within the early bacterial community, but were surpassed by the Betaproteobacteria and Flavobacteria in mid and late phases. Bacterial genera involved in exopolysaccharide production, alkaline phosphatase activity and biopolymer degradation were identified. These attributes are important in the formation, maintenance and break-down of biofilms and therefore strengthen the likelihood of linkages between the micro-algal and bacterial community. Further investigations into functional roles of the biofilm components are needed to infer relationships between P. autumnale and the bacterial community.  A clear pattern of microbial succession is described here and linkages between the micro-algal and bacterial communities are evident. Future work should focus on the functional attributes of microbes occurring at different stages of succession to further understand how P. autumnale dominates these benthic communities.</p>

scholarly journals Characterising the benthic Phormidium autumnale-dominated biofilm community and anatoxin production throughout biofilm succession

2021 ◽  
Author(s):  
◽  
Katie Anne Brasell
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Molecular Techniques ◽  
Algal Community ◽  
Microbial Succession ◽  
Microbial Composition ◽  
Community Shifts ◽  
Biofilm Development ◽  
Biofilm Community ◽  
Over Time

<p>There has been an increase in the prevalence and intensity of Phormidium autumnale-dominated benthic blooms in New Zealand over the last decade. This species produces the potent neurotoxins Anatoxin-a, Homoanatoxin-a and their derivatives, and consumption of P. autumnale biofilms has led to over 70 dog deaths since 2005. The mechanisms regulating the dominance and toxicity of P. autumnale are still unclear, as these blooms can reach high biomass in low nutrient conditions. Benthic biofilms are composed of multiple taxa and usually harbor a complex community of bacteria and other microbes, which can change over time and interact to facilitate biofilm development and metabolic processing. Prior to this thesis, the microbial composition of P. autumnale-dominated biofilms was unknown. This study provides insights into the relationships of this neurotoxic cyanobacterium with microbial components of the biofilm community.  Benthic biofilms were sampled every two to four days for 32 days from three sites in the Hutt River (Wellington) following a high flow event. A combination of microscopy and molecular techniques (bacterial ARISA and Illumina™ sequencing) were used to identify the micro-algal and bacterial components of the biofilm throughout its development. Variation in total anatoxin production was measured using LC-MS and changes in toxic P. autumnale cell numbers were quantified using QPCR. A suite of environmental variables (point velocity, depth, flow, conductivity, temperature and nutrients) were also monitored throughout the study period.  Three distinct phases of microbial succession were identified (early, mid and late) using non-metric multidimensional cluster analyses. The micro-algal community composition (including P. autumnale) shifted from early to mid-phase ca. 16 days after the flushing flow and from mid to late phase at ca. day 30. The ARISA and Illumina™ sequencing showed the bacterial community shifts occurred ca. 4 and 9 days before the respective micro-algal community shifts. These analyses indicate a close coupling of the micro-algal and bacterial communities and may suggest bacterial driven succession. However, bacteria are likely to depend on micro-algal by-products for nutrition from the mid-phases onward and assessment of the metabolic processes occurring within the biofilms is needed to clarify this.  Phormidium autumnale was dominant in the biofilm from an early stage in development and grew exponentially despite an influx of diatoms at day 20. None of the environmental parameters measured could explain the temporal variation in micro-algal and bacterial communities, which suggested that intrinsic rather than extrinsic factors were more important in regulating succession. This further supports the hypothesis that biofilm microbes may facilitate P. autumnale dominance.  There was a significant variation in anatoxins per cell over time (p = 0.034). Production of anatoxins was greatest in the mid-phase of succession (208 fg cell⁻¹), coinciding with an increase in diatom biomass, which could implicate anatoxins as allelopathic chemicals that alleviate the effects of competition on P. autumnale. Changes in proportions of the different anatoxin variants produced over time also aligned with the three successional phases in both the micro-algal and bacterial communities, providing further evidence of a relationship between anatoxin production and microbial biofilm components.  Bacterial taxa of the Alphaproteobacteria were dominant within the early bacterial community, but were surpassed by the Betaproteobacteria and Flavobacteria in mid and late phases. Bacterial genera involved in exopolysaccharide production, alkaline phosphatase activity and biopolymer degradation were identified. These attributes are important in the formation, maintenance and break-down of biofilms and therefore strengthen the likelihood of linkages between the micro-algal and bacterial community. Further investigations into functional roles of the biofilm components are needed to infer relationships between P. autumnale and the bacterial community.  A clear pattern of microbial succession is described here and linkages between the micro-algal and bacterial communities are evident. Future work should focus on the functional attributes of microbes occurring at different stages of succession to further understand how P. autumnale dominates these benthic communities.</p>

scholarly journals Respiratory Heterogeneity Shapes Biofilm Formation and Host Colonization in Uropathogenic Escherichia coli

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Connor J. Beebout ◽  
Allison R. Eberly ◽  
Sabrina H. Werby ◽  
Seth A. Reasoner ◽  
John R. Brannon ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Extracellular Matrix ◽  
Bacterial Communities ◽  
Spatial Organization ◽  
Bet Hedging ◽  
Content Type ◽  
Dna Organization ◽  
Quinol Oxidases ◽  
Biofilm Development ◽  
Biofilm Community

ABSTRACT Biofilms are multicellular bacterial communities encased in a self-secreted extracellular matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of these components lends spatial organization to the biofilm community such that biofilm residents can benefit from the production of common goods while being protected from exogenous insults. Spatial organization is driven by the presence of chemical gradients, such as oxygen. Here we show that two quinol oxidases found in Escherichia coli and other bacteria organize along the biofilm oxygen gradient and that this spatially coordinated expression controls architectural integrity. Cytochrome bd, a high-affinity quinol oxidase required for aerobic respiration under hypoxic conditions, is the most abundantly expressed respiratory complex in the biofilm community. Depletion of the cytochrome bd-expressing subpopulation compromises biofilm complexity by reducing the abundance of secreted extracellular matrix as well as increasing cellular sensitivity to exogenous stresses. Interrogation of the distribution of quinol oxidases in the planktonic state revealed that ∼15% of the population expresses cytochrome bd at atmospheric oxygen concentration, and this population dominates during acute urinary tract infection. These data point toward a bet-hedging mechanism in which heterogeneous expression of respiratory complexes ensures respiratory plasticity of E. coli across diverse host niches. IMPORTANCE Biofilms are multicellular bacterial communities encased in a self-secreted extracellular matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of these components lends spatial organization in the biofilm community. Here we demonstrate that oxygen gradients in uropathogenic Escherichia coli (UPEC) biofilms lead to spatially distinct expression programs for quinol oxidases—components of the terminal electron transport chain. Our studies reveal that the cytochrome bd-expressing subpopulation is critical for biofilm development and matrix production. In addition, we show that quinol oxidases are heterogeneously expressed in planktonic populations and that this respiratory heterogeneity provides a fitness advantage during infection. These studies define the contributions of quinol oxidases to biofilm physiology and suggest the presence of respiratory bet-hedging behavior in UPEC.

scholarly journals Ecological Succession of Bacterial Communities during Conventionalization of Germ-Free Mice

2012 ◽  
Vol 78 (7) ◽  
pp. 2359-2366 ◽  
Author(s):  
Merritt G. Gillilland ◽  
John R. Erb-Downward ◽  
Christine M. Bassis ◽  
Michael C. Shen ◽  
Galen B. Toews ◽  
...  
Keyword(s):  
Bacterial Community ◽  
16S Rrna ◽  
Bacterial Communities ◽  
Structural Heterogeneity ◽  
Ecological Succession ◽  
Rrna Gene ◽  
Gi Tract ◽  
Content Type ◽  
Germ Free ◽  
Over Time

ABSTRACTLittle is known about the dynamics of early ecological succession during experimental conventionalization of the gastrointestinal (GI) tract; thus, we measured changes in bacterial communities over time, at two different mucosal sites (cecum and jejunum), with germfree C57BL/6 mice as the recipients of cecal contents (input community) from a C57BL/6 donor mouse. Bacterial communities were monitored using pyrosequencing of 16S rRNA gene amplicon libraries from the cecum and jejunum and analyzed by a variety of ecological metrics. Bacterial communities, at day 1 postconventionalization, in the cecum and jejunum had lower diversity and were distinct from the input community (dominated by eitherEscherichiaorBacteroides). However, by days 7 and 21, the recipient communities had become significantly diverse and the cecal communities resembled those of the donor and donor littermates, confirming that transfer of cecal contents results in reassembly of the community in the cecum 7 to 21 days later. However, bacterial communities in the recipient jejunum displayed significant structural heterogeneity compared to each other or the donor inoculum or the donor littermates, suggesting that the bacterial community of the jejunum is more dynamic during the first 21 days of conventionalization. This report demonstrates that (i) mature input communities do not simply reassemble at mucosal sites during conventionalization (they first transform into a “pioneering” community and over time take on the appearance, in membership and structure, of the original input community) and (ii) the specific mucosal environment plays a role in shaping the community.

Nutrient availability and organic matter quality shape bacterial community structure in a lake biofilm

2020 ◽  
Vol 85 ◽  
pp. 1-18
Author(s):  
RC Seballos ◽  
KH Wyatt ◽  
RJ Bernot ◽  
SP Brown ◽  
S Chandra ◽  
...  
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Bacterial Community ◽  
Bacterial Community Structure ◽  
Heterotrophic Bacteria ◽  
Interspecific Interactions ◽  
Molecular Techniques ◽  
Nitrogen And Phosphorus ◽  
Microbial Composition ◽  
Organic Matter Quality

Heterotrophic bacteria play a key role in ecosystem processes, but little is known about the factors that shape bacterial community structure in aquatic biofilms, especially in lakes. We used molecular techniques (16S rRNA) to evaluate resource controls on biofilm bacterial community structure in an oligotrophic subalpine lake. We manipulated nutrients (nitrogen and phosphorus; NP) and glucose (G) on inorganic (rock) and organic (wood) substrates under light and dark conditions (i.e. with and without autotrophy, respectively) in a full factorial design using nutrient diffusing substrates in situ for 20 d. Distinct patterns of separation in community structure between treatments with nutrients (NP, NP+G) and without nutrients (control, G-only) indicated that community structure was more strongly influenced by nutrients than organic matter irrespective of substrate type or light availability. Further separation in community structure between treatments with nutrients only (NP) and nutrients with glucose (NP+G) on both organic and inorganic substrates indicated that once nutrient limitation was alleviated, organic matter quality played an important role in shaping community structure. Differences in the relative abundance of 6 phyla, 3 classes, and 19 genera among treatments revealed (1) contrasting taxa-specific resource requirements, (2) the influence of interspecific interactions on composition, and (3) the potential for individual taxa to participate in the decomposition of recalcitrant organic matter. Our findings provide insight into the role that nutrients and organic matter quality play in shaping bacterial community structure, which is a critical step in bridging the knowledge gap between microbial composition and ecosystem function within aquatic environments.

Comparative analysis of biofilm community on different coloured substrata in relation to mussel settlement

2016 ◽  
Vol 97 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Yi-Feng Li ◽  
Xing-Pan Guo ◽  
Yu-Ru Chen ◽  
De-Wen Ding ◽  
Jin-Long Yang
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
High Throughput Sequencing ◽  
Current Knowledge ◽  
Illumina Miseq ◽  
Miseq Sequencing ◽  
Significant Difference ◽  
The World ◽  
Community Variability ◽  
Biofilm Community

Mussels are typical macrofouling organisms in the world. In this study, the interaction between the settlement ofMytilus coruscusplantigrades and bacterial community on coloured substrata was determined. Bacterial communities in biofilms developed on seven coloured substrata were analysed by Illumina Miseq sequencing. The mussel settlement response to coloured substrata with no biofilms was also examined.Flavobacteria, AlphaproteobacteriaandGammaproteobacteriawere the first, second and third most dominant groups in seven biofilm samples. The results suggest that the inducing activities of these biofilms on plantigrade settlement varied with coloured substrata and the lowest percentage of settlement was observed on biofilms on the green substratum. High-throughput sequencing showed that bacterial community in biofilms also changed with the substratum colour. No significant difference in the inducing activity on plantigrade settlement was observed between the coloured substrata with no biofilms. Thus, difference in plantigrade settlement response may be correlated to the changes in bacterial community on coloured substrata. This finding extends current knowledge of interaction among mussel settlement and bacterial community variability.

scholarly journals Biodiversity of Soil Bacterial Communities from the Sasso Fratino Integral Nature Reserve

2021 ◽  
Vol 12 (4) ◽  
pp. 862-877
Author(s):  
Lara Mitia Castronovo ◽  
Sara Del Duca ◽  
Sofia Chioccioli ◽  
Alberto Vassallo ◽  
Donatella Fibbi ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Dna Analysis ◽  
Nature Reserve ◽  
Random Amplified Polymorphic Dna ◽  
Soil Samples ◽  
Microbial Composition ◽  
Rdna Sequencing ◽  
Soil Bacterial

The Sasso Fratino Integral Nature Reserve (Italy) aims to protect nature and territory. Since no anthropic activities are allowed, it represents a good model to study the bacterial community of a wild environment. The aim of this work was to characterise the cultivable and the total bacterial community of soil samples from the reserve in terms of taxonomy, composition, and structure. Seven soil samples were collected at different altitudes, and the chemical composition, the total and the cultivable microbiota, and the antibiotic resistance profiles of isolates were investigated. Total bacterial communities, studied through Next Generation Sequences analysis, included 390 genera. Samples differed in terms of microbial composition basing on the different altitude/vegetation of collection points. Random Amplified Polymorphic DNA Analysis (RAPD) allowed to identify 82 haplotypes out of 158 bacterial isolates. The taxonomic identification through 16S rDNA sequencing revealed that the strains were affiliated to 21 genera. Antibiotic resistance profiles of bacteria were also investigated, highlighting a high resistance against streptomycin and kanamycin. This work represents the first description of the soil bacterial community from the Natural Reserve of Sasso Fratino, and it is the first study considering the soil microbiota of an Italian integral nature reserve.

scholarly journals Colonization of Naive Roots from Populus tremula × alba Involves Successive Waves of Fungi and Bacteria with Different Trophic Abilities

2021 ◽  
Vol 87 (6) ◽  
Author(s):  
F. Fracchia ◽  
L. Mangeot-Peter ◽  
L. Jacquot ◽  
F. Martin ◽  
C. Veneault-Fourrey ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Microbial Communities ◽  
Bacterial Communities ◽  
Laser Scanning Microscopy ◽  
Fungal Communities ◽  
Bulk Soil ◽  
Confocal Laser ◽  
Community Members ◽  
Root Microbiome ◽  
Over Time

ABSTRACT Through their roots, trees interact with a highly complex community of microorganisms belonging to various trophic guilds and contributing to tree nutrition, development, and protection against stresses. Tree roots select for specific microbial species from the bulk soil communities. The root microbiome formation is a dynamic process, but little is known on how the different microorganisms colonize the roots and how the selection occurs. To decipher whether the final composition of the root microbiome is the product of several waves of colonization by different guilds of microorganisms, we planted sterile rooted cuttings of gray poplar obtained from plantlets propagated in axenic conditions in natural poplar stand soil. We analyzed the root microbiome at different time points between 2 and 50 days of culture by combining high-throughput Illumina MiSeq sequencing of the fungal ribosomal DNA internal transcribed spacer and bacterial 16S rRNA amplicons with confocal laser scanning microscopy observations. The microbial colonization of poplar roots took place in three stages, but bacteria and fungi had different dynamics. Root bacterial communities were clearly different from those in the soil after 2 days of culture. In contrast, if fungi were also already colonizing roots after 2 days, the initial communities were very close to that in the soil and were dominated by saprotrophs. They were slowly replaced by endophytes and ectomycorhizal fungi. The replacement of the most abundant fungal and bacterial community members observed in poplar roots over time suggest potential competition effect between microorganisms and/or a selection by the host. IMPORTANCE The tree root microbiome is composed of a very diverse set of bacterial and fungal communities. These microorganisms have a profound impact on tree growth, development, and protection against different types of stress. They mainly originate from the bulk soil and colonize the root system, which provides a unique nutrient-rich environment for a diverse assemblage of microbial communities. In order to better understand how the tree root microbiome is shaped over time, we observed the composition of root-associated microbial communities of naive plantlets of poplar transferred in natural soil. The composition of the final root microbiome relies on a series of colonization stages characterized by the dominance of different fungal guilds and bacterial community members over time. Our observations suggest an early stabilization of bacterial communities, whereas fungal communities are established following a more gradual pattern.

scholarly journals Effects of Neonicotinoid Seed Treatments on Phyllosphere and Soil Bacterial Communities Over Time

2020 ◽  
Author(s):  
Mona Parizadeh ◽  
Benjamin Mimee ◽  
Steven W. Kembel
Keyword(s):  
Bacterial Community ◽  
Plant Growth ◽  
Soil Fertility ◽  
Bacterial Communities ◽  
Agricultural Practices ◽  
Beneficial Bacteria ◽  
Pesticide Application ◽  
Soil Bacterial Communities ◽  
Over Time ◽  
Target Effects

Abstract BackgroundThe phyllosphere and soil are dynamic habitats for microbial communities. Non-pathogenic microbiota, including leaf and soil beneficial bacteria, plays a crucial role in plant growth and health, as well as in soil fertility and organic matter production. In sustainable agriculture, it is important to understand the composition of these bacterial communities, their changes in response to disturbances, and their resilience to agricultural practices. Widespread pesticide application may have had non-target impacts on these beneficial microorganisms. Neonicotinoids are a family of systemic insecticides being vastly used to control soil and foliar pests in recent decades. A few studies have demonstrated the long-term and non-target effects of neonicotinoids on agroecosystem microbiota, but the generality of these findings remains unclear. In this study, we used 16S rRNA gene amplicon sequencing to characterize the effects of neonicotinoid seed treatment on soil and phyllosphere bacterial community diversity, composition and temporal dynamics in a three-year soybean/corn rotation in Quebec, Canada. Results We found that habitat, host species and time are stronger drivers of variation in bacterial composition than neonicotinoid application. They respectively explained 37.3%, 3.2% and 2.9% of the community variation. However, neonicotinoids did have an impact on bacterial community structure, especially on the taxonomic composition of soil communities (2.6%) and over time (2.4%). They also caused a decrease in soil alpha diversity in the middle of the growing season. While the neonicotinoid treatment favored some bacterial genera known as neonicotinoid biodegraders, there was a decline in the relative abundance of some potentially beneficial soil bacteria, such as the plant growth-promoting rhizobacteria and the bacteria involved in the nitrogen cycle, in response to the pesticide application.ConclusionsOur results indicate that neonicotinoids have non-target effects on phyllosphere and soil bacterial communities in a soybean-corn agroecosystem, especially potentially beneficial bacteria that are vital for plant growth and improve soil fertility. Exploring the interactions among bacteria and other organisms, as well as the bacterial functional responses to the pesticide treatment, may enhance our understanding of these non-target effects and help us adapt agricultural practices to control these impacts.

scholarly journals Diverse bacterial communities exist on canine skin and are impacted by cohabitation and time

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3075 ◽  
Author(s):  
Sheila Torres ◽  
Jonathan B. Clayton ◽  
Jessica L. Danzeisen ◽  
Tonya Ward ◽  
Hu Huang ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Bacterial Community Structure ◽  
Skin Microbiome ◽  
Bacterial Populations ◽  
Operational Taxonomic Units ◽  
Hair Type ◽  
Different Seasons ◽  
Over Time

It has previously been shown that domestic dogs and their household owners share bacterial populations, and that sharing of bacteria between humans is facilitated through the presence of dogs in the household. However, less is known regarding the bacterial communities of dogs, how these communities vary by location and over time, and how cohabitation of dogs themselves influences their bacterial community. Furthermore, the effects of factors such as breed, hair coat length, sex, shedding, and age on the canine skin microbiome is unknown. This study sampled the skin bacterial communities of 40 dogs belonging to 20 households longitudinally across three seasons (spring, summer, and winter). Significant differences in bacterial community structure between samples were identified when stratified by season, but not by dog sex, age, breed, hair type, or skin site. Cohabitating dogs were more likely to share bacteria of the skin than non-cohabitating dogs. Similar to human bacterial microbiomes, dogs’ microbiomes were more similar to their own microbiomes over time than to microbiomes of other individuals. Dogs sampled during the same season were also more similar to each other than to dogs from different seasons, irrespective of household. However, there were very few core operational taxonomic units (OTUs) identified across all dogs sampled. Taxonomic classification revealedPropionibacterium acnesandHaemophilussp. as key members of the dog skin bacterial community, along withCorynebacteriumsp. andStaphylococcus epidermidis. This study shows that the skin bacterial community structure of dogs is highly individualized, but can be shared among dogs through cohabitation.

scholarly journals Links between Plant and Rhizoplane Bacterial Communities in Grassland Soils, Characterized Using Molecular Techniques

2005 ◽  
Vol 71 (11) ◽  
pp. 6784-6792 ◽  
Author(s):  
Naoise Nunan ◽  
Timothy J. Daniell ◽  
Brajesh K. Singh ◽  
Artemis Papert ◽  
James W. McNicol ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Plant Species ◽  
Bacterial Communities ◽  
Rhizosphere Soil ◽  
Bacterial Community Composition ◽  
Molecular Techniques ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Grassland Soils

ABSTRACT Molecular analysis of grassland rhizosphere soil has demonstrated complex and diverse bacterial communities, with resultant difficulties in detecting links between plant and bacterial communities. These studies have, however, analyzed “bulk” rhizosphere soil, rather than rhizoplane communities, which interact most closely with plants through utilization of root exudates. The aim of this study was to test the hypothesis that plant species was a major driver for bacterial rhizoplane community composition on individual plant roots. DNA extracted from individual roots was used to determine plant identity, by analysis of the plastid tRNA leucine (trnL) UAA gene intron, and plant-related bacterial communities. Bacterial communities were characterized by analysis of PCR-amplified 16S rRNA genes using two fingerprinting methods: terminal restriction fragment length polymorphisms (T-RFLP) and denaturing gradient gel electrophoresis (DGGE). Links between plant and bacterial rhizoplane communities could not be detected by visual examination of T-RFLP patterns or DGGE banding profiles. Statistical analysis of fingerprint patterns did not reveal a relationship between bacterial community composition and plant species but did demonstrate an influence of plant community composition. The data also indicated that topography and other, uncharacterized, environmental factors are important in driving bacterial community composition in grassland soils. T-RFLP had greater potential resolving power than DGGE, but findings from the two methods were not significantly different.

Sign in / Sign up

Export Citation Format

Share Document