Fe(III) Reducing Microorganisms from Iron Ore Caves Demonstrate Fermentative Fe(III) Reduction and Promote Cave Formation

Parker, Ceth W.; Auler, Augusto S.; Barton, Michael D.; Sasowsky, Ira D.; Senko, John M.; Barton, Hazel A.

doi:10.1080/01490451.2017.1368741

Cited by 39 publications

(60 citation statements)

References 69 publications

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“…It is important to note that our results differ from recent findings in Brazil. Parker et al (34) linked microbial iron reduction in the highly weathered BIF systems in Brazil to cave formation, i.e. , the overall broad scale dissolution rather than net formation of iron oxides.…”

Section: Discussionmentioning

confidence: 99%

“…More specifically, the presence, diversity, and importance of microbial groups contributing to iron dissolution and precipitation processes in canga formation remain unknown. Parker et al (34) investigated biogeochemical processes in caves in the canga areas of Brazil and suggested that microbial processes contribute to overall iron oxide dissolution and cave formation. To date, no study has demonstrated how microbial processes contribute to iron oxide formation within canga ecosystems.…”

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confidence: 99%

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Microbial Diversity in Actively Forming Iron Oxides from Weathered Banded Iron Formation Systems

et al. 2018

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The surface crust that caps highly weathered banded iron formations (BIFs) supports a unique ecosystem that is a post-mining restoration priority in iron ore areas. Geochemical evidence indicates that biological processes drive the dissolution of iron oxide minerals and contribute to the ongoing evolution of this duricrust. However, limited information is available on present-day biogeochemical processes in these systems, particularly those that contribute to the precipitation of iron oxides and, thus, the cementation and stabilization of duricrusts. Freshly formed iron precipitates in water bodies perched on cangas in Karijini National Park, Western Australia, were sampled for microscopic and molecular analyses to understand currently active microbial contributions to iron precipitation in these areas. Microscopy revealed sheaths and stalks associated with iron-oxidizing bacteria. The iron-oxidizing lineages Sphaerotilus, Sideroxydans, and Pedomicrobium were identified in various samples and Leptothrix was common in four out of five samples. The iron-reducing bacteria Anaeromyxobacter dehalogens and Geobacter lovleyi were identified in the same four samples, with various heterotrophs and diverse cyanobacteria. Given this arid, deeply weathered environment, the driver of contemporary iron cycling in Karijini National Park appears to be iron-reducing bacteria, which may exist in anaerobic niches through associations with aerobic heterotrophs. Overall oxidizing conditions and Leptothrix iron-oxidizers contribute to net iron oxide precipitation in our sampes, rather than a closed biogeochemical cycle, which would result in net iron oxide dissolution as has been suggested for canga caves in Brazil. Enhancements in microbial iron oxide dissolution and subsequent reprecipitation have potential as a surface-crust-ecosystem remediation strategy at mine sites.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Microbial Diversity in Actively Forming Iron Oxides from Weathered Banded Iron Formation Systems

et al. 2018

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“…The average iron content of cave sediments has been estimated to range between 0.1-2.0% (Sasowsky & Mylroie, 2004;Sasowsky, pers. comm., 2020), and given that Fe(III) can be recycled to Fe(II) by microbial activity in cave sediments, this suggests that even trace iron in the environment is sufficient to catalyze the Fenton reaction (Schwertmann, 1991;Parker et al, 2018).…”

Section: Potentially Toxicmentioning

confidence: 99%

“…The reactive species are dangerous to biological systems, causing extensive DNA damage and mutagenesis, even at pmol concentrations (Winterbourn, 1995). This activity can be accentuated in cave environments by the microbially-enhanced dissolution of iron oxides, which is promoted under the mineral grain size and chemistry of iron-rich sediments similar to those in caves (Schwertmann, 1991;Parker et al, 2018). Indeed, in the past, researchers who have demonstrated the successful use of hydrogen peroxide to remove lampenflora, only did so when high concentration solutions (>15%) were used, which required the use of protective respirators and goggles given the poor ventilation in caves and noxious gases produced (Meyer et al, 2017).…”

Section: Special Consideration On the Use Of Hydrogen Peroxidementioning

confidence: 99%

Safe and effective disinfection of show cave infrastructure in a time of COVID-19

Barton¹

2020

IJS

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The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has been responsible for over 650,000 deaths worldwide. Transmission of SARS-CoV-2 occurs primarily through airborne transmission or direct human contact, demonstrating the importance of social distancing measures and the use of face masks to prevent infection. Nonetheless, the persistence of coronavirus on surfaces means that disinfection is important to limit the possibility of contact transmission. In this paper, the potential for various surfaces in show caves to serve as sources for SARS-CoV-2 infection is examined. Given the isoelectric potential (pI) of SARS and SARS-like coronaviruses, it is likely that they are adsorbed via electrochemical interactions to (limestone) rock surfaces, where the high humidity, pH and presence of biocarbonate ions will quickly lead to inactivation. Nonetheless, show caves contain infrastructure made of other non-porous surfaces that are more permissive for maintaining coronavirus viability. The 423 antiviral products approved by the US Environmental Protection Agency (EPA) were curated into 23 antiviral chemistries, which were further classified based on their potential to be hazardous, impact cave features or ecosystems, and those compounds likely to have the minimum impact on caves. The results suggest that alcohols (70% ethanol), organic acids (citric and lactic acid) and dilute hypochlorite represent the best disinfectants for in-cave use on non-porous surfaces. These disinfectants are able to inactivate coronaviruses inecosystems.

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“…They present a distinct mineralogical composition, associated with rocks [1,2,3] that provide an opportunity for colonization by different microbial communities. Recently, there was an increase in the number of studies conducted on microbial communities in tropical caves, especially those close to the Equator line (such as Brazilian caves) [4,5,6,7,8]. However, these caves represent only a small fraction of the many existing tropical caves, and most of these studies are based on cultured fungi and bacteria [5,7].…”

Section: Introductionmentioning

confidence: 99%

Purple Sulfur Bacteria Dominate Microbial Community in Brazilian Limestone Cave

et al. 2019

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The mineralogical composition of caves makes the environment ideal for inhabitation by microbes. However, the bacterial diversity in the cave ecosystem remains largely unexplored. In this paper, we described the bacterial community in an oxic chamber of the Sopradeira cave, an iron-rich limestone cave, in the semiarid region of Northeast Brazil. The microbial population in the cave samples was studied by 16S rDNA next-generation sequencing. A type of purple sulfur bacteria (PSB), Chromatiales, was found to be the most abundant in the sediment (57%), gravel-like (73%), and rock samples (96%). The predominant PSB detected were Ectothiorhodospiraceae, Chromatiaceae, and Woeseiaceae. We identified the PSB in a permanently aphotic zone, with no sulfur detected by energy-dispersive X-ray (EDX) spectroscopy. The absence of light prompted us to investigate for possible nitrogen fixing (nifH) and ammonia oxidizing (amoA) genes in the microbial samples. The nifH gene was found to be present in higher copy numbers than the bacterial-amoA and archaeal-amoA genes, and archaeal-amoA dominated the ammonia-oxidizing community. Although PSB dominated the bacterial community in the samples and may be related to both nitrogen-fixing and ammonia oxidizing bacteria, nitrogen-fixing associated gene was the most detected in those samples, especially in the rock. The present work demonstrates that this cave is an interesting hotspot for the study of ammonia-oxidizing archaea and aphotic PSB.

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Fe(III) Reducing Microorganisms from Iron Ore Caves Demonstrate Fermentative Fe(III) Reduction and Promote Cave Formation

Cited by 39 publications

References 69 publications

Microbial Diversity in Actively Forming Iron Oxides from Weathered Banded Iron Formation Systems

Microbial Diversity in Actively Forming Iron Oxides from Weathered Banded Iron Formation Systems

Safe and effective disinfection of show cave infrastructure in a time of COVID-19

Purple Sulfur Bacteria Dominate Microbial Community in Brazilian Limestone Cave

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