Rhizosphere Bacteria and Phytostabilization Success: The Association Between Bacteria, Plant Establishment and Metal(loid) Immobilization in Metalliferous Mine Tailings

Persistent Link:
http://hdl.handle.net/10150/624161
Title:
Rhizosphere Bacteria and Phytostabilization Success: The Association Between Bacteria, Plant Establishment and Metal(loid) Immobilization in Metalliferous Mine Tailings
Author:
Honeker, Linnea Katherine
Issue Date:
2017
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release after 03-Apr-2019
Abstract:
Phytostabilization offers a less expensive alternative to traditional cap and plant methods for containing metalliferous mine tailings to prevent wind erosion and contamination of nearby communities and the environment. However, plant establishment during phytostabilization of pyritic legacy mine tailings in semiarid regions is challenging due to particularly extreme conditions including low pH, low organic carbon, low nutrients, and high toxic metal(loid) concentrations. Microorganisms drive major biogeochemical cycles in soils, however, the roles microorganisms play at the root – soil interface during phytostabilization, particularly in relation to plant health and metal immobilization, are not yet fully understood. The aims of this dissertation are to focus on bacterial communities associated with the roots of buffalo grass used in the phytostabilization of pyritic metalliferous mine tailings to: i) characterize bacterial diversity and communities of rhizosphere and bulk substrate, ii) delineate associations between rhizoplane bacterial colonization patterns and environmental and plant status parameters, and iii) develop an in situ method to visually assess associations between roots, bacteria, and metals. Key findings indicate that after addition of a compost amendment to alleviate the plant-growth inhibiting characteristics of mine tailings, rhizosphere and bulk substrate contain a diverse, plant-growth supporting bacterial community. As substrate re-acidifies due to compost erosion, an emergence of an iron (Fe)- and sulfur (S)-oxidizer and Fe-reducer dominated, less diverse community develops in the bulk and rhizosphere substrate, thus posing a threat to successful plant establishment. However, even at low pH, some plant-growth-promoting bacteria are still evident in the rhizosphere. On the rhizoplane (root surface), the relative abundance of metabolically active bacteria was positively correlated with plant health, verifying the strong association between plant health and bacteria. Furthermore, pH showed a strong association with the relative abundance of Alphaproteobacteria and Gammaproteobacteria on the rhizoplane. In relation to microbe-metal interactions on the root surface, results showed that Actinobacteria and Alphaproteobacteria colocalized with Fe-plaque and arsenic (As) contaminant on the root surface, indicating their potential role in adsorbing or cycling of these metal(loid)s. Developing a more thorough understanding of bacteria-root-metal interactions in relation to plant health and metal immobilization can help to improve phytostabilization efforts and success.
Type:
text; Electronic Dissertation
Keywords:
Metal(loid) contamination; Mine tailings; Phytostabilization; Plant roots; Rhizobacteria; Rhizosphere
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water & Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Maier, Raina M.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleRhizosphere Bacteria and Phytostabilization Success: The Association Between Bacteria, Plant Establishment and Metal(loid) Immobilization in Metalliferous Mine Tailingsen_US
dc.creatorHoneker, Linnea Katherineen
dc.contributor.authorHoneker, Linnea Katherineen
dc.date.issued2017-
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.releaseRelease after 03-Apr-2019en
dc.description.abstractPhytostabilization offers a less expensive alternative to traditional cap and plant methods for containing metalliferous mine tailings to prevent wind erosion and contamination of nearby communities and the environment. However, plant establishment during phytostabilization of pyritic legacy mine tailings in semiarid regions is challenging due to particularly extreme conditions including low pH, low organic carbon, low nutrients, and high toxic metal(loid) concentrations. Microorganisms drive major biogeochemical cycles in soils, however, the roles microorganisms play at the root – soil interface during phytostabilization, particularly in relation to plant health and metal immobilization, are not yet fully understood. The aims of this dissertation are to focus on bacterial communities associated with the roots of buffalo grass used in the phytostabilization of pyritic metalliferous mine tailings to: i) characterize bacterial diversity and communities of rhizosphere and bulk substrate, ii) delineate associations between rhizoplane bacterial colonization patterns and environmental and plant status parameters, and iii) develop an in situ method to visually assess associations between roots, bacteria, and metals. Key findings indicate that after addition of a compost amendment to alleviate the plant-growth inhibiting characteristics of mine tailings, rhizosphere and bulk substrate contain a diverse, plant-growth supporting bacterial community. As substrate re-acidifies due to compost erosion, an emergence of an iron (Fe)- and sulfur (S)-oxidizer and Fe-reducer dominated, less diverse community develops in the bulk and rhizosphere substrate, thus posing a threat to successful plant establishment. However, even at low pH, some plant-growth-promoting bacteria are still evident in the rhizosphere. On the rhizoplane (root surface), the relative abundance of metabolically active bacteria was positively correlated with plant health, verifying the strong association between plant health and bacteria. Furthermore, pH showed a strong association with the relative abundance of Alphaproteobacteria and Gammaproteobacteria on the rhizoplane. In relation to microbe-metal interactions on the root surface, results showed that Actinobacteria and Alphaproteobacteria colocalized with Fe-plaque and arsenic (As) contaminant on the root surface, indicating their potential role in adsorbing or cycling of these metal(loid)s. Developing a more thorough understanding of bacteria-root-metal interactions in relation to plant health and metal immobilization can help to improve phytostabilization efforts and success.en
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectMetal(loid) contaminationen
dc.subjectMine tailingsen
dc.subjectPhytostabilizationen
dc.subjectPlant rootsen
dc.subjectRhizobacteriaen
dc.subjectRhizosphereen
thesis.degree.namePh.D.en
thesis.degree.leveldoctoralen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineSoil, Water & Environmental Scienceen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorMaier, Raina M.en
dc.contributor.committeememberMaier, Raina M.en
dc.contributor.committeememberChorover, Jon D.en
dc.contributor.committeememberRich, Virginia I.en
dc.contributor.committeememberVercelli, Donataen
dc.contributor.committeememberVedantam, Gayatrien
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