ORCID Profile
0000-0003-4818-0824
Current Organisations
CSIRO Land and Water
,
University of Adelaide
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Publications
Terraced Iron Formations: Biogeochemical Processes Contributing to Microbial Biomineralization and Microfossil Preservation
Publisher: MDPI AG
Date: 13-12-2018
DOI: 10.3390/GEOSCIENCES8120480
Abstract: Terraced iron formations (TIFs) are laminated structures that cover square meter-size areas on the surface of weathered bench faces and tailings piles at the Mount Morgan mine, which is a non-operational open pit mine located in Queensland, Australia. S led TIFs were analyzed using molecular and microanalytical techniques to assess the bacterial communities that likely contributed to the development of these structures. The bacterial community from the TIFs was more erse compared to the tailings on which the TIFs had formed. The detection of both chemolithotrophic iron-oxidizing bacteria, i.e., Acidithiobacillus ferrooxidans and Mariprofundus ferrooxydans, and iron-reducing bacteria, i.e., Acidobacterium capsulatum, suggests that iron oxidation/reduction are continuous processes occurring within the TIFs. Acidophilic, iron-oxidizing bacteria were enriched from the TIFs. High-resolution electron microscopy was used to characterize iron biomineralization, i.e., the association of cells with iron oxyhydroxide mineral precipitates, which served as an analog for identifying the structural microfossils of in idual cells as well as biofilms within iron oxyhydroxide laminations—i.e., alternating layers containing schwertmannite (Fe16O16(OH)12(SO4)2) and goethite (FeO(OH)). Kinetic modeling estimated that it would take between 0.25–2.28 years to form approximately one gram of schwertmannite as a lamination over a one-m2 surface, thereby contributing to TIF development. This length of time could correspond with seasonable rainfall or greater than average annual rainfall. In either case, the presence of water is critical for sustaining microbial activity, and subsequently iron oxyhydroxide mineral precipitation. The TIFs from the Mount Morgan mine also contain laminations of gypsum (CaSO·2H2O) alternating with iron oxyhydroxide laminations. These gypsum laminations likely represented drier periods of the year, in which millimeter-size gypsum crystals presumably precipitated as water gradually evaporated. Interestingly, gypsum acted as a substrate for the attachment of cells and the growth of biofilms that eventually became mineralized within schwertmannite and goethite. The dissolution and reprecipitation of gypsum suggest that microenvironments with circumneutral pH conditions could exist within TIFs, thereby supporting iron oxidation under circumneutral pH conditions. In conclusion, this study highlights the relationship between microbes for the development of TIFs and also provides interpretations of biogeochemical processes contributing to the preservation of bacterial cells and entire biofilms under acidic conditions.
Bacterial biofilms on gold grains—implications for geomicrobial transformations of gold
Publisher: Oxford University Press (OUP)
Date: 19-04-2016
Abstract: The biogeochemical cycling of gold (Au), i.e. its solubilization, transport and re-precipitation, leading to the (trans)formation of Au grains and nuggets has been demonstrated under a range of environmental conditions. Biogenic (trans)formations of Au grains are driven by (geo)biochemical processes mediated by distinct biofilm consortia living on these grains. This review summarizes the current knowledge concerning the composition and functional capabilities of Au-grain communities, and identifies contributions of key-species involved in Au-cycling. To date, community data are available from grains collected at 10 sites in Australia, New Zealand and South America. The majority of detected operational taxonomic units detected belong to the α-, β- and γ-Proteobacteria and the Actinobacteria. A range of organisms appears to contribute predominantly to biofilm establishment and nutrient cycling, some affect the mobilization of Au via excretion of Au-complexing ligands, e.g. organic acids, thiosulfate and cyanide, while a range of resident Proteobacteria, especially Cupriavidus metallidurans and Delftia acidovorans, have developed Au-specific biochemical responses to deal with Au-toxicity and reductively precipitate mobile Au-complexes. This leads to the biomineralization of secondary Au and drives the environmental cycle of Au.
Comparative diversity and heavy metal biosorption of myxomycetes from forest patches on ultramafic and volcanic soils
Publisher: Informa UK Limited
Date: 17-11-2015
Diversity of plasmodial slime molds (myxomycetes) in coastal, mountain, and community forests of Puerto Galera, Oriental Mindoro, the Philippines
Publisher: Elsevier BV
Date: 12-2015
Biogeochemical cycling of gold: Transforming gold particles from arctic Finland
Publisher: Elsevier BV
Date: 04-2018
Rapid assessment of myxomycete diversity in the Bicol Peninsula, Philippines
Publisher: Schweizerbart
Date: 02-2017
Myxomycetes associated with grassland litter in the Philippines
Publisher: Mushroom Research Foundation
Date: 2017
DOI: 10.5943/CREAM/7/2/1
Radionuclides and stable elements in vegetation in Australian arid environments: Concentration ratios and seasonal variation
Publisher: Elsevier BV
Date: 08-2021
A comparative species listing of myxomycetes from tropical (Philippines) and temperate (United States) forests
Publisher: Mushroom Research Foundation
Date: 02-2014
Gold particles from Kamchatka: A brief look at gold biogeochemical cycling in a distinct environment
Publisher: Mineralogical Society
Date: 02-2021
DOI: 10.1180/MGM.2021.17
Abstract: Kamchatka is a peninsula located on the far eastern side of Russia and is a geologically active region within the Pacific Ring of Fire. Placer gold particles were obtained from a stream located in the Yelizovsky District and were compared to particles from regions at similar latitudes. Russian gold particle surface textures and morphologies were characterised optically and using electron microscopy, and bacteria occurring on the surface of particles were inferred from detected licon sequence variants (ASVs). The gold particles contained remarkably variable gold surface textures with an average 70% of surface area containing clay-filled concavities. Particle morphologies, interpreted from axis ratios, suggested that these particles were transported from primary sources. Proteobacteria constituted 60% of all the detected ASVs from the particles. Within this phylum, Gammaproteobacteria was the most dominant class. This study contributes to the understanding of gold biogeochemical cycling in a distinct bioclimatic environment.
Toxicity assessment of gold ions and gold nanoparticles to golden perch larvae (Macquaria ambigua)
Publisher: Mineralogical Society
Date: 02-2021
DOI: 10.1180/MGM.2021.14
Abstract: Golden perch ( Macquaria ambigua ) is a freshwater game-fish native to central and southeast Australia. Larvae of this fish species were used in two different types of experiments to evaluate the effects of short-term exposures (up to 6 days) to aqueous gold, 5 nm gold nanoparticles (AuNPs), or 50 nm AuNPs. Relative to the control, increased gold concentrations corresponded with yolk-sac edema (swelling). Larvae exposed to 50 μM of 5 nm AuNPs had yolk-sacs that were ~1.5 times larger resulting in the appearance of bent notochords. After two days of exposure, 100% mortality was observed. Total mortalities were % in the other larvae–gold systems, suggesting that these larvae can quickly adapt to the presence of gold. In terms of an oxidative stress response, the larvae from all systems did not express high enzymatic activity. The state of the gold determined how much could be taken up (or immobilised) by a larva. Aqueous gold and 5 nm AuNPs easily pass through cells therefore, larvae exposed to these forms of gold contained the highest concentrations. Scanning electron microscopy confirmed that cells comprising the epithelium and fins contained AuNPs. Aqueous gold was reduced to nanometre-scale particles within cells. Comparatively, 5 nm AuNPs appeared to be aggregated within cells forming clusters hundreds of nanometres in size. On the contrary, 50 nm AuNPs were not observed within cells but were detected within larvae by (single particle) inductively coupled plasma mass spectroscopy, suggesting that these AuNPs were probably taken up through the mouth or gills. The results of the present study demonstrate that exposure to AuNPs had adverse effects on developing golden perch larvae. Additionally, these effects were dependent on the size of the AuNPs.
Progressive biogeochemical transformation of placer gold particles drives compositional changes in associated biofilm communities
Publisher: Oxford University Press (OUP)
Date: 03-05-2018
Abstract: Biofilms on placer gold (Au)-particle surfaces drive Au solubilization and re-concentration thereby progressively transforming the particles. Gold solubilization induces Au-toxicity however, Au-detoxifying community members ameliorates Au-toxicity by precipitating soluble Au to metallic Au. We hypothesize that Au-dissolution and re-concentration (precipitation) place selective pressures on associated microbial communities, leading to compositional changes and subsequent Au-particle transformation. We analyzed Au-particles from eight United Kingdom sites using next generation sequencing, electron microscopy and micro-analyses. Gold particles contained biofilms composed of prokaryotic cells and extracellular polymeric substances intermixed with (bio)minerals. Across all sites communities were dominated by Proteobacteria (689, 97% Operational Taxonomic Units, 59.3% of total reads), with β-Proteobacteria being the most abundant. A wide range of Au-morphotypes including nanoparticles, micro-crystals, sheet-like Au and secondary rims, indicated that dissolution and re-precipitation occurred, and from this transformation indices were calculated. Multivariate statistical analyses showed a significant relationship between the extent of Au-particle transformation and biofilm community composition, with putative metal-resistant Au-cycling taxa linked to progressive Au transformation. These included the genera Pseudomonas, Leptothrix and Acinetobacter. Additionally, putative exoelectrogenic genera Rhodoferax and Geobacter were highly abundant. In conclusion, biogeochemical Au-cycling and Au-particle transformation occurred at all sites and exerted a strong influence on biofilm community composition.
Does the primary deposit affect the biogeochemical transformation of placer gold and associated biofilms?
Publisher: Elsevier BV
Date: 09-2019
Oxidative Dissolution of Sulfide Minerals in Single and Mixed Sulfide Systems under Simulated Acid and Metalliferous Drainage Conditions
Publisher: American Chemical Society (ACS)
Date: 28-01-2021
Biological and Geochemical Development of Placer Gold Deposits at Rich Hill, Arizona, USA
Publisher: MDPI AG
Date: 08-02-2018
DOI: 10.3390/MIN8020056
Plasmodial Slime Molds of a Tropical Karst Forest, Quezon National Park, the Philippines
Publisher: Pacific Science
Date: 07-2015
DOI: 10.2984/69.3.9
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Related Funding Activities
No related grants have been discovered for Maria Angelica Rea.