The agricultural sector in Canada is responsible for approximately 9% of greenhouse gas (GHG) emissions in Canada, accounting for 54 MT of carbon dioxide (CO 2 ), as well as 31% of methane (CH 4 ) and 75% of national nitrous oxide (N 2 O) emissions in 2021 (Environment and Climate Change Canada 2021). However, these estimates do not include the indirect GHG emissions that occur in agriculturally impacted waterways. Ontario is home to over 45 000 kilometers of agricultural drainage ditches, with tile drains directly connecting terrestrial and aquatic environments. Microbial biogeochemical cycles in the causeways experience fluxes of nutrients leading to hotspots for GHG at the sediment-water interfaces. Along with fluxes of nutrients, the causeways are regularly disturbed by anthropogenic effects (e.g., dredging, removal of vegetative buffers) and increasing frequency of storm events. Previous studies have used static chambers to evaluate GHG emissions from aquatic systems (Mu et al. 2022, Xiao et al. 2016). However, this approach can be time consuming and labour intensive and is impractical in aquatic systems due potential extensive underestimation of fluxes from diffusion. To resolve driving factors contributing to GHG in these systems a detailed study investigating the activity of the microbial community is warranted. In this study we hypothesize microbial activity within the sediment will correlate with N 2 O emissions. To test the response of the microbial community a combination of molecular approaches (i.e., qPCR and Ion torrent) targeting archaeal and bacterial nitrifiers and denitrifies was used. These functional responses were evaluated with respect to N 2 O emissions, which were measured in the field at the time of sampling using Unisense N 2 O probes. In this study, N 2 O sensor response was calibrated to a functional gene index for rapid risk assessment of GHG hotspots.
加拿大的农业部门约占加拿大温室气体(GHG)排放量的9%，占2021年二氧化碳(CO 2)的54公吨，以及31%的甲烷(CH 4)和75%的全国一氧化二氮(n2o)排放量(加拿大环境与气候变化2021年)。然而，这些估计不包括在受农业影响的水道中发生的间接温室气体排放。安大略省拥有超过45,000公里的农业排水沟，瓷砖排水沟直接连接陆地和水生环境。堤道中的微生物生物地球化学循环经历了养分的通量，导致沉积物-水界面的温室气体热点。随着营养物质的流动，堤道经常受到人为影响(如疏浚、移除植被缓冲)和风暴事件频率增加的干扰。以前的研究使用静态室来评估水生系统的温室气体排放(Mu et al. 2022, Xiao et al. 2016)。然而，这种方法可能是耗时和劳动密集型的，并且在水生系统中是不切实际的，因为可能广泛低估了扩散通量。为了解决这些系统中造成温室气体的驱动因素，有必要对微生物群落的活动进行详细的研究。在这项研究中，我们假设沉积物中的微生物活动与氮排放有关。为了测试微生物群落的反应，采用了针对古细菌和细菌硝化菌和反硝化菌的分子方法(即qPCR和离子流)的组合。这些功能响应是根据氮排放来评估的，氮排放是在采样时使用Unisense氮探针在现场测量的。本研究将氮氧传感器响应校准为一个功能基因指数，用于快速评估温室气体热点地区的风险。
{"title":"Investigating Microbial Triggers of Nitrous Oxide Emissions in Agriculturally Influenced Aquatic Ecosystems","authors":"C Crundwell, Lori Phillips, Chris Weisener","doi":"10.3897/aca.6.e107604","DOIUrl":"https://doi.org/10.3897/aca.6.e107604","url":null,"abstract":"The agricultural sector in Canada is responsible for approximately 9% of greenhouse gas (GHG) emissions in Canada, accounting for 54 MT of carbon dioxide (CO 2 ), as well as 31% of methane (CH 4 ) and 75% of national nitrous oxide (N 2 O) emissions in 2021 (Environment and Climate Change Canada 2021). However, these estimates do not include the indirect GHG emissions that occur in agriculturally impacted waterways. Ontario is home to over 45 000 kilometers of agricultural drainage ditches, with tile drains directly connecting terrestrial and aquatic environments. Microbial biogeochemical cycles in the causeways experience fluxes of nutrients leading to hotspots for GHG at the sediment-water interfaces. Along with fluxes of nutrients, the causeways are regularly disturbed by anthropogenic effects (e.g., dredging, removal of vegetative buffers) and increasing frequency of storm events. Previous studies have used static chambers to evaluate GHG emissions from aquatic systems (Mu et al. 2022, Xiao et al. 2016). However, this approach can be time consuming and labour intensive and is impractical in aquatic systems due potential extensive underestimation of fluxes from diffusion. To resolve driving factors contributing to GHG in these systems a detailed study investigating the activity of the microbial community is warranted. In this study we hypothesize microbial activity within the sediment will correlate with N 2 O emissions. To test the response of the microbial community a combination of molecular approaches (i.e., qPCR and Ion torrent) targeting archaeal and bacterial nitrifiers and denitrifies was used. These functional responses were evaluated with respect to N 2 O emissions, which were measured in the field at the time of sampling using Unisense N 2 O probes. In this study, N 2 O sensor response was calibrated to a functional gene index for rapid risk assessment of GHG hotspots.","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Teto Seitshiro, Naji Bassil, Oliver Moore, Jonathan Lloyd
Geogenic arsenic contamination of groundwater in South and South-East Asia poses a significant human health threat, causing a range of health conditions including but not limited to cardio-vascular disease, cancer and skin lesions (Argos et al. 2010, Pienkowska et al. 2021). Arsenic contamination also hosts a range of dire socioeconomic implications for the affected areas. A variety of mechanisms for arsenic release in anoxic aquifers have been proposed, however, the most widely accepted mechanism is the microbial reduction of As-bearing Fe(III) (oxyhydr)oxide minerals coupled with the oxidation of organic carbon (Glodowska et al. 2020, Gnanaprakasam et al. 2017). Recent research has implicated methane as a possible carbon source in the reduction of Fe(III) (oxyhydr)oxide minerals and the subsequent release of arsenic into the groundwater (Gnanaprakasam et al. 2017, Pienkowska et al. 2021). The research suggests that methanotrophs have the ability to drive anaerobic oxidation of methane, AOM, coupled to Fe(III) (oxyhydr)oxide reduction. In this study, we aim to provide unequivocal evidence for the occurrence of AOM coupled to Fe(III) (oxyhydr)oxide as well to further explore the exact mechanism(s) involved which is yet to be characterised. Here we present an overview of our work so far.
南亚和东南亚地下水的地质砷污染对人类健康构成重大威胁，造成一系列健康状况，包括但不限于心血管疾病、癌症和皮肤病变(Argos等人，2010年;Pienkowska等人，2021年)。砷污染还会给受影响地区带来一系列可怕的社会经济影响。人们提出了缺氧含水层中砷释放的多种机制，然而，最被广泛接受的机制是含砷铁(III)(氧)氧化物矿物的微生物还原以及有机碳的氧化(Glodowska et al. 2020, Gnanaprakasam et al. 2017)。最近的研究表明，甲烷可能是Fe(III)(氧合)氧化物矿物还原和随后将砷释放到地下水中的碳源(Gnanaprakasam等人，2017年，Pienkowska等人，2021年)。研究表明，甲烷氧化菌具有驱动甲烷厌氧氧化的能力，AOM，耦合Fe(III)(氧)氧化物还原。在这项研究中，我们的目标是为AOM与Fe(III)(氧合)氧化物耦合的发生提供明确的证据，并进一步探索尚未表征的确切机制。在这里，我们概述了迄今为止我们的工作。
{"title":"Application of geomicrobial techniques to constrain mechanisms of arsenic mobilisation in anoxic aquifers","authors":"Teto Seitshiro, Naji Bassil, Oliver Moore, Jonathan Lloyd","doi":"10.3897/aca.6.e107756","DOIUrl":"https://doi.org/10.3897/aca.6.e107756","url":null,"abstract":"Geogenic arsenic contamination of groundwater in South and South-East Asia poses a significant human health threat, causing a range of health conditions including but not limited to cardio-vascular disease, cancer and skin lesions (Argos et al. 2010, Pienkowska et al. 2021). Arsenic contamination also hosts a range of dire socioeconomic implications for the affected areas. A variety of mechanisms for arsenic release in anoxic aquifers have been proposed, however, the most widely accepted mechanism is the microbial reduction of As-bearing Fe(III) (oxyhydr)oxide minerals coupled with the oxidation of organic carbon (Glodowska et al. 2020, Gnanaprakasam et al. 2017). Recent research has implicated methane as a possible carbon source in the reduction of Fe(III) (oxyhydr)oxide minerals and the subsequent release of arsenic into the groundwater (Gnanaprakasam et al. 2017, Pienkowska et al. 2021). The research suggests that methanotrophs have the ability to drive anaerobic oxidation of methane, AOM, coupled to Fe(III) (oxyhydr)oxide reduction. In this study, we aim to provide unequivocal evidence for the occurrence of AOM coupled to Fe(III) (oxyhydr)oxide as well to further explore the exact mechanism(s) involved which is yet to be characterised. Here we present an overview of our work so far.","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A major question for the Alberta oilsands extraction industry is how to return tailings ponds to their original ecosystem functions at the end of their lifespan. This question is one of the most pressing in the oil industry, and while many potential solutions are being trialed, none are without issue. One solution is the creation of end pit lakes (EPLs), formed by filling a mine pit or tailings pond with fluid tailings and covering this with a freshwater cap. Over time, tailings settle to the bottom of the lake and become sequestered. As of 2018, there were 23 plans to pursue EPLs in Albertan oilsands mining operations (COSIA 2021), so research in oilsands reclamation via EPLs is essential. Alberta has only one full-scale EPL formed using tailings, Base Mine Lake (BML). It has been under reclamation since 2011. Although BML water quality is gradually improving over time, one persistent problem is the production of methane bubbles from the entrenched hydrocarbons. Ebullition of these bubbles carries contaminants into the water column. The potential to limit methane production biologically by stimulating methanotroph metabolism, is therefore of interest. Methanotrophs are microbes that consume methane. These methanotrophs can be aerobic, in the water column, or anaerobic below the sediment interface, where oxygen is depleted. Anaerobic oxidizers of methane, or AOM, are of particular interest due to methane only being produced in anaerobic conditions. However, AOM are not well-studied and there are many gaps in our knowledge about them. Base Mine Lake presents an important opportunity to document the presence of AOM in oilsands ecosystems, and identify if AOM can remove methane before it enters the water column. Methane is probably not the limiting factor for AOM in BML- instead, the electron acceptors used in the absence of oxygen are scarce. If microbiological methane removal were to increase after supplementing electron acceptors such as nitrate, sulfate, or iron, then this could be applied to the reclamation of artificial end pit lake systems. Our research aims to illustrate if AOM are present in BML, and if we can stimulate their metabolism via electron acceptor amendment. We performed amplicon and metagenomic sequencing across 5 sediment cores from BML. These cores penetrate over two meters below the water-sediment interface, up to 14 meters below the water’s surface. We designed anaerobic, 13 C-isotope-spiked incubations for this sediment to track if any CH 4 to CO 2 conversion was underway. By tagging methane molecules with 13 C, we are able to follow the biogeochemical transformations and demonstrate if any 13 CH 4 is converted to 13 CO 2 , which would indicate methanotrophic activity. Additionally, microbes who take up 13 C produce heavier DNA, possibly allowing us to identify the DNA of the players at work. Additionally, Illumina sequencing was done on all incubations to compare how electron acceptor addition prompted community shifts. In
{"title":"Electron Acceptor Addition to Stimulate Anaerobic Methanotrophy in Oil Sands End Pit Lakes ","authors":"Hanna Davidson, Peter Dunfield","doi":"10.3897/aca.6.e108078","DOIUrl":"https://doi.org/10.3897/aca.6.e108078","url":null,"abstract":"A major question for the Alberta oilsands extraction industry is how to return tailings ponds to their original ecosystem functions at the end of their lifespan. This question is one of the most pressing in the oil industry, and while many potential solutions are being trialed, none are without issue. One solution is the creation of end pit lakes (EPLs), formed by filling a mine pit or tailings pond with fluid tailings and covering this with a freshwater cap. Over time, tailings settle to the bottom of the lake and become sequestered. As of 2018, there were 23 plans to pursue EPLs in Albertan oilsands mining operations (COSIA 2021), so research in oilsands reclamation via EPLs is essential. Alberta has only one full-scale EPL formed using tailings, Base Mine Lake (BML). It has been under reclamation since 2011. Although BML water quality is gradually improving over time, one persistent problem is the production of methane bubbles from the entrenched hydrocarbons. Ebullition of these bubbles carries contaminants into the water column. The potential to limit methane production biologically by stimulating methanotroph metabolism, is therefore of interest. Methanotrophs are microbes that consume methane. These methanotrophs can be aerobic, in the water column, or anaerobic below the sediment interface, where oxygen is depleted. Anaerobic oxidizers of methane, or AOM, are of particular interest due to methane only being produced in anaerobic conditions. However, AOM are not well-studied and there are many gaps in our knowledge about them. Base Mine Lake presents an important opportunity to document the presence of AOM in oilsands ecosystems, and identify if AOM can remove methane before it enters the water column. Methane is probably not the limiting factor for AOM in BML- instead, the electron acceptors used in the absence of oxygen are scarce. If microbiological methane removal were to increase after supplementing electron acceptors such as nitrate, sulfate, or iron, then this could be applied to the reclamation of artificial end pit lake systems. Our research aims to illustrate if AOM are present in BML, and if we can stimulate their metabolism via electron acceptor amendment. We performed amplicon and metagenomic sequencing across 5 sediment cores from BML. These cores penetrate over two meters below the water-sediment interface, up to 14 meters below the water’s surface. We designed anaerobic, 13 C-isotope-spiked incubations for this sediment to track if any CH 4 to CO 2 conversion was underway. By tagging methane molecules with 13 C, we are able to follow the biogeochemical transformations and demonstrate if any 13 CH 4 is converted to 13 CO 2 , which would indicate methanotrophic activity. Additionally, microbes who take up 13 C produce heavier DNA, possibly allowing us to identify the DNA of the players at work. Additionally, Illumina sequencing was done on all incubations to compare how electron acceptor addition prompted community shifts. In","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maicon Araujo, Daniela Gutierrez Rueda, Yuhao Li, Janice Kenney, Daniel Alessi, Kurt Konhauser
Surfaces of prokaryotic cells play a significant role in the adsorption of metals from aqueous solution and the formation of authigenic minerals (Konhauser 2006). Although most studies focus on the cell wall, it is known that many bacteria synthesise an extracellular layer of polysaccharides and proteins, including what are known as sheaths. It has been shown that the cyanobacterium Calothrix sp. produces as sheath which is neutrally charged at circumneutral pH values, and it was hypothesized that such a sheath might allow the cyanobacterium to survive in geothermal settings with high silicification rates (Phoenix et al. 2002). Specifically, the dominance of hydroxyl sites on Calothrix ’s sheath surface facilitates hydrogen bonding with aqueous silica species, inducing the precipitation of amorphous silica on the sheath and thus protecting the underlying cell (Phoenix et al. 2002). Leptothrix cholodnii is a sheathed, iron and manganese-oxidizing bacterium that frequently inhabits minerals seeps, where Fe 2+ and Mn 2+ discharge into oxygenated surface waters (Spring et al. 1996). As a result, the sheath becomes encrusted with Fe(III) and Mn(IV) oxyhydroxides while the underlying cells are protected from mineralization (Emerson and Ghiorse 1992, Emerson et al. 2010). However, unlike Calothrix, Leptothrix’ s sheath composition suggests that it might behave differently at circumneutral pH (Emerson and Ghiorse 1993). To investigate the surface reactivity of Leptothrix 's sheath and cell wall we analyzed isolated sheaths, sheathless cells, and intact filaments of L. cholodnii SP-6. We studied these components using potentiometric titration, zeta-potential, Cd-adsorption, and Fourier transform infrared (FTIR) spectroscopy to elucidate changes in surface charge between the cell wall and sheath. For the isolated sheaths and intact filaments, titration data were fit using a two-site protonation model, resulting in the following pKa values: 6.05 (±0.29) and 9.34 (±0.11); and 7.77 (±0.17) and 10.50 (±0.20), respectively. For the sheathless cells, the best fit was obtained by using a three-site protonation model, resulting in the following pKa values: 5.40 (±0.59), 8.11 (±1.64) and 10.73 (±0.45). Total proton-active site concentrations were lower in isolated sheaths compared to intact filaments. Additionally, at circumneutral pH, net negative charge was lower for sheathless cells compared to intact filaments and isolated sheaths (Fig. 1). This information agrees with the Cd adsorption behaviour found for the three materials (Fig. 2). Thus, our preliminary results suggest that Leptothrix ’s sheath is less reactive than the intact filaments at circumneutral pH, leading us to hypothesize that the outermost layer would sequester relatively lower amounts of cations, including Mn 2+ , from solution and potentially would protect the underlaying cell from deleterious mineralization. In addition to that, the less reactive sheath’s surface would also contribute to cell
原核细胞的表面对水溶液中金属的吸附和自生矿物的形成起着重要的作用(Konhauser 2006)。尽管大多数研究集中在细胞壁上，但众所周知，许多细菌合成细胞外的多糖和蛋白质层，包括被称为鞘的物质。研究表明，蓝细菌Calothrix sp.产生的鞘在环中性pH值下具有中性电荷，并且假设这种鞘可能允许蓝细菌在高硅化率的地热环境中生存(Phoenix et al. 2002)。具体来说，钙思鞘表面羟基位点的优势促进了与水性二氧化硅的氢键，诱导了鞘上无定形二氧化硅的沉淀，从而保护了下面的细胞(Phoenix et al. 2002)。胆氏细螺旋体是一种被护套的铁和锰氧化细菌，经常栖息在矿物质渗漏中，其中铁2+和锰2+排放到含氧地表水中(Spring et al. 1996)。因此，鞘层被铁(III)和锰(IV)氢氧化物包裹，而下面的细胞受到保护，免受矿化(Emerson和Ghiorse 1992, Emerson et al. 2010)。然而，与钩丝虱不同的是，钩丝虱的鞘成分表明，它在环中性pH下的行为可能不同(Emerson和giorse 1993)。为了研究钩螺旋体鞘和细胞壁的表面反应性，我们分析了分离的L. cholodnii SP-6鞘、无鞘细胞和完整的细丝。我们使用电位滴定、ζ电位、cd吸附和傅里叶变换红外(FTIR)光谱来研究这些成分，以阐明细胞壁和鞘之间表面电荷的变化。对于分离的鞘和完整的细丝，采用两点质子化模型拟合滴定数据，得到的pKa值分别为6.05(±0.29)和9.34(±0.11);分别为7.77(±0.17)和10.50(±0.20)。对于无鞘细胞，采用三位点质子化模型拟合最佳，得到的pKa值分别为5.40(±0.59)、8.11(±1.64)和10.73(±0.45)。与完整的细丝相比，分离鞘中的总质子活性位点浓度较低。此外，在环中性的pH下，与完整的细丝和分离的鞘相比，无鞘细胞的净负电荷更低(图1)。这一信息与三种材料的Cd吸附行为一致(图2)。因此，我们的初步结果表明，细刺虫的鞘比完整的细丝在环中性的pH下反应性更低，这使我们假设最外层会隔离相对较少的阳离子，包括Mn 2+。从溶液中，可能会保护下层细胞免受有害的矿化。除此之外，反应性较低的鞘表面也有助于细胞附着，这对溪流中常见的物种很重要(Phoenix et al. 2002, Emerson et al. 2010)。
{"title":"Surface reactivity of the iron and manganese-oxidizing bacterium Leptothrix cholodnii SP-6","authors":"Maicon Araujo, Daniela Gutierrez Rueda, Yuhao Li, Janice Kenney, Daniel Alessi, Kurt Konhauser","doi":"10.3897/aca.6.e108135","DOIUrl":"https://doi.org/10.3897/aca.6.e108135","url":null,"abstract":"Surfaces of prokaryotic cells play a significant role in the adsorption of metals from aqueous solution and the formation of authigenic minerals (Konhauser 2006). Although most studies focus on the cell wall, it is known that many bacteria synthesise an extracellular layer of polysaccharides and proteins, including what are known as sheaths. It has been shown that the cyanobacterium Calothrix sp. produces as sheath which is neutrally charged at circumneutral pH values, and it was hypothesized that such a sheath might allow the cyanobacterium to survive in geothermal settings with high silicification rates (Phoenix et al. 2002). Specifically, the dominance of hydroxyl sites on Calothrix ’s sheath surface facilitates hydrogen bonding with aqueous silica species, inducing the precipitation of amorphous silica on the sheath and thus protecting the underlying cell (Phoenix et al. 2002). Leptothrix cholodnii is a sheathed, iron and manganese-oxidizing bacterium that frequently inhabits minerals seeps, where Fe 2+ and Mn 2+ discharge into oxygenated surface waters (Spring et al. 1996). As a result, the sheath becomes encrusted with Fe(III) and Mn(IV) oxyhydroxides while the underlying cells are protected from mineralization (Emerson and Ghiorse 1992, Emerson et al. 2010). However, unlike Calothrix, Leptothrix’ s sheath composition suggests that it might behave differently at circumneutral pH (Emerson and Ghiorse 1993). To investigate the surface reactivity of Leptothrix 's sheath and cell wall we analyzed isolated sheaths, sheathless cells, and intact filaments of L. cholodnii SP-6. We studied these components using potentiometric titration, zeta-potential, Cd-adsorption, and Fourier transform infrared (FTIR) spectroscopy to elucidate changes in surface charge between the cell wall and sheath. For the isolated sheaths and intact filaments, titration data were fit using a two-site protonation model, resulting in the following pKa values: 6.05 (±0.29) and 9.34 (±0.11); and 7.77 (±0.17) and 10.50 (±0.20), respectively. For the sheathless cells, the best fit was obtained by using a three-site protonation model, resulting in the following pKa values: 5.40 (±0.59), 8.11 (±1.64) and 10.73 (±0.45). Total proton-active site concentrations were lower in isolated sheaths compared to intact filaments. Additionally, at circumneutral pH, net negative charge was lower for sheathless cells compared to intact filaments and isolated sheaths (Fig. 1). This information agrees with the Cd adsorption behaviour found for the three materials (Fig. 2). Thus, our preliminary results suggest that Leptothrix ’s sheath is less reactive than the intact filaments at circumneutral pH, leading us to hypothesize that the outermost layer would sequester relatively lower amounts of cations, including Mn 2+ , from solution and potentially would protect the underlaying cell from deleterious mineralization. In addition to that, the less reactive sheath’s surface would also contribute to cell","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When an animal dies the decomposition of its carcass releases multiple compounds that become available to soil microbiota altering soil biogeochemistry. This zone of affected substrate is characterized by significant changes to numerous soil biogeochemical parameters including pH, conductivity, microbial respiration rates, dissolved organic carbon (DOC), C/N ratios, carbon and nitrogen stable isotopes (δ 13 C and δ 15 N), and major/trace elemental concentrations. Although the effects of animal decomposition on these parameters have been recorded for various organisms and in a variety of ecosystems several knowledge gaps remain, including: the effect of carcass size; and decomposition effects in prairie ecosystems (i.e., semi-arid climates). the effect of carcass size; and decomposition effects in prairie ecosystems (i.e., semi-arid climates). Here, we investigate how soil biogeochemical parameters are affected by the decomposition of a horse carcass (~660 kg) in a prairie ecosystem in comparison to beavers (~18 kg) in a temperate forest. Three parameters were identified as significantly influenced by carcass size: conductivity, DOC, and microbial respiration rate. Average soil conductivity underneath the horse carcass was three to fifteen times higher than control soils and reached a maximum at 1114 ADD, while maximum soil conductivity values were observed after 160 ADD in beaver-associated soils. Maximum DOC concentrations were observed after 160 ADD in beaver-associated soil (67 ± 40 mg C gdw -1 ) and after 1114 ADD in horse-associated soil (326 ± 115 mg C gdw -1 ). Microbial respirations rates were both greater in horse-associated soil and longer-lasting compared to beaver-associated soil. Respiration rates were greatest in two of the three horse-associated soils after 1114 ADD (~733 µg CO 2 -C gdw -1 day -1 ), which significantly differs compared to beaver-associated soils (300 ± 90 µg CO 2 -C gdw -1 day -1 at 160 ADD). Taken together, these results demonstrate that larger carcasses result in a greater release of decomposition products, including C, and greater stimulation of soil heterotrophic communities. Other measured biogeochemical indicators of decay suggest a mixed influence due to carcass size and climate, notably δ 15 N values of the soil, and major element concentrations. Climate was revealed to be more important in controlling changes to pH and gravimetric moisture than carcass size, with baseline soil conditions and type playing critical roles. Additionally, in semi-arid regions such as western South Dakota, the role of wet-dry cycles on carcasses undergoing decomposition may help to explain the pulses observed with C concentrations and C cycling. This study provides the first direct comparison of soil biogeochemistry associated with the decomposition of two different sized taxa decayed in two different climates. Attempting to normalize climate data using ADD was found to be an imperfect system that does not account for all climat
当动物死亡时，其尸体的分解释放出多种化合物，这些化合物可以被土壤微生物群利用，从而改变土壤的生物地球化学。受影响的底物区域的特征是大量土壤生物地球化学参数发生显著变化，包括pH、电导率、微生物呼吸速率、溶解有机碳(DOC)、C/N比、碳和氮稳定同位素(δ 13c和δ 15n)以及主要/痕量元素浓度。尽管动物分解对各种生物和各种生态系统中这些参数的影响已被记录，但仍存在一些知识空白，包括:胴体大小的影响;以及草原生态系统(即半干旱气候)的分解效应。胴体尺寸的影响;以及草原生态系统(即半干旱气候)的分解效应。在这里，我们研究了草原生态系统中马尸体(~660公斤)的分解对土壤生物地球化学参数的影响，并与温带森林中海狸尸体(~18公斤)的分解进行了比较。3个参数受胴体尺寸的显著影响:电导率、DOC和微生物呼吸速率。马胴体下土壤电导率是对照土壤的3 ~ 15倍，在ADD值为1114时达到最大值，而与海狸相关的土壤电导率在ADD值为160时达到最大值。在海狸伴生土壤中，添加160℃(67±40 mg C gdw -1)和在马伴生土壤中添加1114℃(326±115 mg C gdw -1)后，DOC浓度最高。与海狸相关的土壤相比，马相关土壤中的微生物呼吸率更高，持续时间更长。在1114 ADD(~733µg CO 2 -C gdw -1 day -1)后，三种马相关土壤中的两种土壤的呼吸速率最高，与海狸相关土壤(300±90µg CO 2 -C gdw -1 day -1 at 160 ADD)相比差异显著。综上所述，这些结果表明，更大的尸体导致更多的分解产物释放，包括C，和更大的刺激土壤异养群落。其他测量的腐烂生物地球化学指标表明，由于胴体尺寸和气候，特别是土壤的δ 15 N值和主要元素浓度的混合影响。气候对pH和重水分的影响比胴体尺寸的影响更大，其中基线土壤条件和土壤类型起关键作用。此外，在半干旱地区，如南达科他州西部，干湿循环对腐烂尸体的作用可能有助于解释用C浓度和C循环观察到的脉冲。本研究首次直接比较了两种不同气候条件下两种不同大小分类群腐烂的土壤生物地球化学特征。试图使用ADD规范气候数据被发现是一个不完善的系统，它没有考虑到影响分解的所有气候变量。解开分解模式可以更好地帮助约束现代和古代生态系统中的营养循环。
{"title":"Disentangling carcass size and climate effects on soil biogeochemistry during decomposition","authors":"Sarah Keenan, Colette McAndrew, Scott Beeler","doi":"10.3897/aca.6.e107627","DOIUrl":"https://doi.org/10.3897/aca.6.e107627","url":null,"abstract":"When an animal dies the decomposition of its carcass releases multiple compounds that become available to soil microbiota altering soil biogeochemistry. This zone of affected substrate is characterized by significant changes to numerous soil biogeochemical parameters including pH, conductivity, microbial respiration rates, dissolved organic carbon (DOC), C/N ratios, carbon and nitrogen stable isotopes (δ 13 C and δ 15 N), and major/trace elemental concentrations. Although the effects of animal decomposition on these parameters have been recorded for various organisms and in a variety of ecosystems several knowledge gaps remain, including: the effect of carcass size; and decomposition effects in prairie ecosystems (i.e., semi-arid climates). the effect of carcass size; and decomposition effects in prairie ecosystems (i.e., semi-arid climates). Here, we investigate how soil biogeochemical parameters are affected by the decomposition of a horse carcass (~660 kg) in a prairie ecosystem in comparison to beavers (~18 kg) in a temperate forest. Three parameters were identified as significantly influenced by carcass size: conductivity, DOC, and microbial respiration rate. Average soil conductivity underneath the horse carcass was three to fifteen times higher than control soils and reached a maximum at 1114 ADD, while maximum soil conductivity values were observed after 160 ADD in beaver-associated soils. Maximum DOC concentrations were observed after 160 ADD in beaver-associated soil (67 ± 40 mg C gdw -1 ) and after 1114 ADD in horse-associated soil (326 ± 115 mg C gdw -1 ). Microbial respirations rates were both greater in horse-associated soil and longer-lasting compared to beaver-associated soil. Respiration rates were greatest in two of the three horse-associated soils after 1114 ADD (~733 µg CO 2 -C gdw -1 day -1 ), which significantly differs compared to beaver-associated soils (300 ± 90 µg CO 2 -C gdw -1 day -1 at 160 ADD). Taken together, these results demonstrate that larger carcasses result in a greater release of decomposition products, including C, and greater stimulation of soil heterotrophic communities. Other measured biogeochemical indicators of decay suggest a mixed influence due to carcass size and climate, notably δ 15 N values of the soil, and major element concentrations. Climate was revealed to be more important in controlling changes to pH and gravimetric moisture than carcass size, with baseline soil conditions and type playing critical roles. Additionally, in semi-arid regions such as western South Dakota, the role of wet-dry cycles on carcasses undergoing decomposition may help to explain the pulses observed with C concentrations and C cycling. This study provides the first direct comparison of soil biogeochemistry associated with the decomposition of two different sized taxa decayed in two different climates. Attempting to normalize climate data using ADD was found to be an imperfect system that does not account for all climat","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This presentation reviews some recent and ongoing research on phosphorus (P) cycling in a variety of lake systems. Phosphorus is an essential nutrient element, and its anthropogenic enrichment is generally considered to be the main driver of cultural eutrophication of freshwater lakes, which, in the worst case, leads to the occurrence of harmful algal blooms, the intensification of hypoxia and the die-off of aquatic life. The research presented shows that excess external P loading causes the accumulation of reactive chemical P forms in the bottom sediments of lakes (Update #1). The slow release of this reactive legacy P back to the water column can significantly delay a lake’s recovery following the reduction of external P loading (Update #2). Land use changes accompanying agricultural intensification and urbanization generally increase P emissions, but the implementation of agricultural and stormwater best management practices can effectively mitigate external P loads to receiving lakes (Update #3). However, additional stressors, including climate change and salinization, magnify in-lake P mobilization pathways and, hence, increase the risks of lake (re-)eutrophication (Update #4).
{"title":"Phosphorus and Lake Eutrophication: Recent Findings and Emerging Challenges","authors":"Philippe Van Cappellen","doi":"10.3897/aca.6.e107183","DOIUrl":"https://doi.org/10.3897/aca.6.e107183","url":null,"abstract":"This presentation reviews some recent and ongoing research on phosphorus (P) cycling in a variety of lake systems. Phosphorus is an essential nutrient element, and its anthropogenic enrichment is generally considered to be the main driver of cultural eutrophication of freshwater lakes, which, in the worst case, leads to the occurrence of harmful algal blooms, the intensification of hypoxia and the die-off of aquatic life. The research presented shows that excess external P loading causes the accumulation of reactive chemical P forms in the bottom sediments of lakes (Update #1). The slow release of this reactive legacy P back to the water column can significantly delay a lake’s recovery following the reduction of external P loading (Update #2). Land use changes accompanying agricultural intensification and urbanization generally increase P emissions, but the implementation of agricultural and stormwater best management practices can effectively mitigate external P loads to receiving lakes (Update #3). However, additional stressors, including climate change and salinization, magnify in-lake P mobilization pathways and, hence, increase the risks of lake (re-)eutrophication (Update #4).","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jingzhi Liang, Hardiljeet Boparai, Line Lomheim, Ariel Nunez Garcia, Elizabeth Edwards, Denis O'Carroll, Brent Sleep
In situ chemical reduction of chlorinated volatile organic compounds (cVOCs) by nano zero-valent iron (nZVI) has been widely applied in the past 20 years, but with limited effectiveness for bare nZVI due to rapid particle settling, short lifespan, and low reactivity. Stabilization and sulfidation of nZVI have improved its mobility and longevity, increased reactivity towards cVOCs, and reduced toxicity to microbes (Nunez Garcia et al. 2021). In the first-ever CMC-S-nZVI field trial, nZVI sulfidated by dithionite (S-nZVI) and stabilized by carboxymethyl cellulose (CMC) was injected into the subsurface of a site contaminated with a wide range of cVOCs. Multi-level wells were installed to monitor the transport of the CMC-S-nZVI suspension and its remedial performance for two years. Short-term (0-17 days) monitoring demonstrated a good transport of the suspension in the down- and up-gradient wells, in terms of total iron, boron, and sulfides which were major constituents of CMC-S-nZVI. Changes in concentrations of parent compounds, intermediates, and ethene showed effective dechlorination of high-chlorinated VOCs such as tetrachloroethene (PCE) and carbon tetrachloride (Nunez Garcia et al. 2020a, Nunez Garcia et al. 2020b). Long-term (157-729 days) performance was evaluated through temporal analyses of microbial communities, total iron, boron, and cVOCs in groundwater samples. Microbial populations, including organohalide-respiring bacteria, increased by >1 order of magnitude; with Geobacter being the most abundant. This long-term enrichment can be attributed to the low toxicity of CMC-S-nZVI and biostimulation by CMC and perhaps Fe 3+ . Non-metric multidimensional scaling analysis was carried out on microbial data grouped by depth range and proximity to the injection well. At locations that clearly received CMC-S-nZVI, there was a significant shift in microbial communities that was sustained for the long term. Iron concentrations increased substantially in long-term samples while boron concentrations decreased, suggesting that this iron did not come from CMC-S-nZVI. Microbial dissolution of iron minerals might have contributed to the increased iron content (Jones et al. 2006). Excess dithionite in CMC-S-nZVI would also have reductively dissolved native iron from the soil, as successfully demonstrated in the in situ redox manipulation (ISRM) technology wherein subsurface Fe 3+ in soil was reduced to Fe 2+ for long-term remedial purposes (Vermeul et al. 2000). Long-term changes in concentrations of lesser-chlorinated VOCs and hydrocarbons suggest that PCE was degraded via both the microbially-mediated sequential hydrogenolysis as well as the abiotic β-elimination. The intermediate vinyl chloride (VC) surprisingly did not accumulate in the current study, in contrast to the significant VC accumulation in a previous un-sulfidated CMC-nZVI trial at the same location (Kocur et al. 2016). Excess dithionite injected in this study might have avoided VC
近20年来，纳米零价铁(nZVI)原位化学还原氯化挥发性有机化合物(cVOCs)的研究得到了广泛应用，但由于纳米零价铁颗粒沉降快、寿命短、反应活性低，其效果有限。nZVI的稳定和硫化改善了其流动性和寿命，增加了对cVOCs的反应性，降低了对微生物的毒性(Nunez Garcia et al. 2021)。在首次CMC-S-nZVI现场试验中，将经二亚硫土(S-nZVI)硫化并经羧甲基纤维素(CMC)稳定的nZVI注入被多种cVOCs污染的场地地下。为了监测CMC-S-nZVI悬浮液的输送及其补救效果，该公司安装了多井，持续了两年。短期(0-17天)监测显示，CMC-S-nZVI的主要成分——总铁、硼和硫化物在上下梯度井中运移良好。母体化合物、中间体和乙烯浓度的变化表明，四氯乙烯(PCE)和四氯化碳等高氯化挥发性有机化合物可有效脱氯(Nunez Garcia et al. 2020a, Nunez Garcia et al. 2020b)。通过对地下水样品中微生物群落、总铁、总硼和cVOCs的时间分析来评估长期(157-729天)的性能。微生物种群，包括有机盐呼吸细菌，增加了1个数量级;其中最丰富的是地杆菌。这种长期富集可归因于CMC- s - nzvi的低毒性和CMC和fe3 +的生物刺激。对微生物数据进行了非度量多维尺度分析，这些数据按深度范围和与注入井的距离分组。在明确接受CMC-S-nZVI的地点，微生物群落发生了长期持续的重大变化。铁浓度在长期样品中显著增加，而硼浓度下降，表明铁不是来自CMC-S-nZVI。微生物对铁矿物的溶解可能导致了铁含量的增加(Jones et al. 2006)。CMC-S-nZVI中过量的二亚硝酸盐也会从土壤中还原溶解天然铁，正如原位氧化还原操作(ISRM)技术成功证明的那样，该技术将土壤中的地下铁3+还原为铁2+，以达到长期补救目的(Vermeul等人，2000)。低氯化VOCs和碳氢化合物浓度的长期变化表明，PCE是通过微生物介导的顺序氢解和非生物β消除来降解的。令人惊讶的是，在目前的研究中，中间体氯乙烯(VC)没有积累，而之前在同一地点进行的未硫化CMC-nZVI试验中，VC积累显著(Kocur et al. 2016)。在本研究中注射过量的二亚硝酸盐可能避免了VC积累，正如先前报道的ISRM处理cvocs污染部位(Vermeul et al. 2000)。此外，已鉴定的细菌种群可能利用硫(来自二亚硫土分解)和铁形成硫化铁，这可以通过原位生物地球化学转化去除氯代挥发性有机化合物(Kennedy et al. 2006)。综上所述，本研究证明了CMC-S-nZVI在地下通过非生物、生物和生物刺激过程去除cVOCs的长期效率。
{"title":"Subsurface Transport of Sulfidated Nano Zero Valent Iron and In Situ Biogeochemical Transformation of Chlorinated Solvents: A Field Study","authors":"Jingzhi Liang, Hardiljeet Boparai, Line Lomheim, Ariel Nunez Garcia, Elizabeth Edwards, Denis O'Carroll, Brent Sleep","doi":"10.3897/aca.6.e107556","DOIUrl":"https://doi.org/10.3897/aca.6.e107556","url":null,"abstract":"In situ chemical reduction of chlorinated volatile organic compounds (cVOCs) by nano zero-valent iron (nZVI) has been widely applied in the past 20 years, but with limited effectiveness for bare nZVI due to rapid particle settling, short lifespan, and low reactivity. Stabilization and sulfidation of nZVI have improved its mobility and longevity, increased reactivity towards cVOCs, and reduced toxicity to microbes (Nunez Garcia et al. 2021). In the first-ever CMC-S-nZVI field trial, nZVI sulfidated by dithionite (S-nZVI) and stabilized by carboxymethyl cellulose (CMC) was injected into the subsurface of a site contaminated with a wide range of cVOCs. Multi-level wells were installed to monitor the transport of the CMC-S-nZVI suspension and its remedial performance for two years. Short-term (0-17 days) monitoring demonstrated a good transport of the suspension in the down- and up-gradient wells, in terms of total iron, boron, and sulfides which were major constituents of CMC-S-nZVI. Changes in concentrations of parent compounds, intermediates, and ethene showed effective dechlorination of high-chlorinated VOCs such as tetrachloroethene (PCE) and carbon tetrachloride (Nunez Garcia et al. 2020a, Nunez Garcia et al. 2020b). Long-term (157-729 days) performance was evaluated through temporal analyses of microbial communities, total iron, boron, and cVOCs in groundwater samples. Microbial populations, including organohalide-respiring bacteria, increased by >1 order of magnitude; with Geobacter being the most abundant. This long-term enrichment can be attributed to the low toxicity of CMC-S-nZVI and biostimulation by CMC and perhaps Fe 3+ . Non-metric multidimensional scaling analysis was carried out on microbial data grouped by depth range and proximity to the injection well. At locations that clearly received CMC-S-nZVI, there was a significant shift in microbial communities that was sustained for the long term. Iron concentrations increased substantially in long-term samples while boron concentrations decreased, suggesting that this iron did not come from CMC-S-nZVI. Microbial dissolution of iron minerals might have contributed to the increased iron content (Jones et al. 2006). Excess dithionite in CMC-S-nZVI would also have reductively dissolved native iron from the soil, as successfully demonstrated in the in situ redox manipulation (ISRM) technology wherein subsurface Fe 3+ in soil was reduced to Fe 2+ for long-term remedial purposes (Vermeul et al. 2000). Long-term changes in concentrations of lesser-chlorinated VOCs and hydrocarbons suggest that PCE was degraded via both the microbially-mediated sequential hydrogenolysis as well as the abiotic β-elimination. The intermediate vinyl chloride (VC) surprisingly did not accumulate in the current study, in contrast to the significant VC accumulation in a previous un-sulfidated CMC-nZVI trial at the same location (Kocur et al. 2016). Excess dithionite injected in this study might have avoided VC ","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"247 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maicon Araujo, Fernando Rossi, Amanda Bendia, Flavia Callefo, Evelyn Sanchez, Alessandra Vasconcelos, Douglas Galante, Fabio Rodrigues
Caves are among the most singular and understudied environments on Earth. Due to the harsh conditions observed in many caves, including scarcity of nutrients and low levels of light, these ecosystems are considered extreme environments (Gabriel and Northup 2012). Therefore, it may be worth paying special attention to the microbial communities existing in these unique systems. Previously, it has been suggested that the high levels of Manganese (Mn) and Iron (Fe) at Lechuguilla and Spider Caves in the United States may influence their microbial community structure in different ways (Northup et al. 2003, Carmichael and Bräuer 2015). In this context, caves are promising environments for investigating microbial functional capabilities in relation to these elements and the ecological interactions that allow these microbes to thrive. Monte Cristo cave (MCC) - in Diamantina, Brazil - was chosen for this study. The cave is located in a region known for historic mining activity and occurrences of Mn and Fe-rich rocks (Costa et al. 2003). With that in mind, our main goal is to investigate if within the microbial community of MCC there is evidence of taxa and genes associated with Fe and Mn metabolism. The samples were collected in 2018 from walls and saprolite deposits within MCC. Community DNA from three samples, P1b, P3 and P7, were independently sequenced using Illumina shotgun sequencing, and the data were analysed using conventional metagenomic pipelines and in-house python scripts. Taxonomic classification was assessed using Kraken2; Fe related genes with FeGenie; and Mn related genes were predicted using BlastP against a collection of manually curated Mn-oxidizing proteins. Environmental Mn and Fe concentrations were measured using ICP-OES. Our results suggest the presence of a microbial community potentially able to change Fe and Mn redox states. In sites P1b and P7, genes associated to Fe and Mn oxidation were identified, Fig. 1. Taxonomic evidence for these metabolisms includes the presence of the taxa Comamonadaceae and Hyphomicrobiaceae, both families that were previously reported to harbour species able to oxidize Mn and Fe (Spring and Kämpfer 2015, Carmichael and Bräuer 2015). Our analysis also assigned contigs to the archaeal phyla Crenarchaeota, Euryarchaeota and Thaumarchaeota, whose presence has been associated with oligotrophic caves where archaea play a role in primary production (Ortiz et al. 2013) (Fig. 2). Moreover, the phylum Euryarchaeota harbours members that use Fe or Mn as electron acceptors during methane oxidation (Ettwig et al. 2016). Our results therefore contribute to understanding how microbial communities of MCC may be playing a role in the biogeochemical cycles of Fe and Mn under the conditions imposed by the subterranean environment, which might reflect similar processes in other caves yet to be explored by a metagenomics approach.
洞穴是地球上最奇特、研究最不足的环境之一。由于在许多洞穴中观察到的恶劣条件，包括营养物质的缺乏和低水平的光照，这些生态系统被认为是极端环境(Gabriel和Northup 2012)。因此，可能值得特别关注这些独特系统中存在的微生物群落。此前，有人提出，美国的Lechuguilla和Spider Caves中锰(Mn)和铁(Fe)的高水平可能以不同的方式影响其微生物群落结构(Northup et al. 2003, Carmichael and Bräuer 2015)。在这种情况下，洞穴是研究微生物与这些元素相关的功能能力和允许这些微生物茁壮成长的生态相互作用的有希望的环境。这项研究选择了巴西迪亚曼蒂纳的基督山洞穴(MCC)。该洞穴位于一个以历史悠久的采矿活动和富锰和富铁岩石的出现而闻名的地区(Costa et al. 2003)。考虑到这一点，我们的主要目标是调查MCC的微生物群落中是否存在与铁和锰代谢相关的分类群和基因的证据。这些样本于2018年从MCC内部的岩壁和腐岩沉积物中采集。使用Illumina霰弹枪测序技术对P1b、P3和P7三个样本的群落DNA进行独立测序，并使用传统的宏基因组管道和内部python脚本对数据进行分析。采用Kraken2进行分类;含FeGenie的铁相关基因;利用BlastP对人工筛选的锰氧化蛋白进行预测。采用ICP-OES法测定环境锰、铁浓度。我们的研究结果表明，微生物群落的存在可能会改变铁和锰的氧化还原状态。在P1b和P7位点，鉴定出与Fe和Mn氧化相关的基因，见图1。这些代谢的分类学证据包括Comamonadaceae和Hyphomicrobiaceae分类群的存在，这两个科以前都报道过能够氧化Mn和Fe的物种(Spring和Kämpfer 2015, Carmichael和Bräuer 2015)。我们的分析还为古细菌门Crenarchaeota, Euryarchaeota和Thaumarchaeota进行了配置，它们的存在与古细菌在初级生产中发挥作用的寡营养洞穴有关(Ortiz等人，2013)(图2)。此外，Euryarchaeota门的成员在甲烷氧化过程中使用Fe或Mn作为电子受体(Ettwig等人，2016)。因此，我们的研究结果有助于了解MCC微生物群落在地下环境条件下如何在铁和锰的生物地球化学循环中发挥作用，这可能反映了其他尚未通过宏基因组学方法探索的洞穴中的类似过程。
{"title":"Shotgun metagenomics from Monte Cristo cave (Brazil) reveals microbial metabolic potential related to iron and manganese biogeochemical cycles ","authors":"Maicon Araujo, Fernando Rossi, Amanda Bendia, Flavia Callefo, Evelyn Sanchez, Alessandra Vasconcelos, Douglas Galante, Fabio Rodrigues","doi":"10.3897/aca.6.e108139","DOIUrl":"https://doi.org/10.3897/aca.6.e108139","url":null,"abstract":"Caves are among the most singular and understudied environments on Earth. Due to the harsh conditions observed in many caves, including scarcity of nutrients and low levels of light, these ecosystems are considered extreme environments (Gabriel and Northup 2012). Therefore, it may be worth paying special attention to the microbial communities existing in these unique systems. Previously, it has been suggested that the high levels of Manganese (Mn) and Iron (Fe) at Lechuguilla and Spider Caves in the United States may influence their microbial community structure in different ways (Northup et al. 2003, Carmichael and Bräuer 2015). In this context, caves are promising environments for investigating microbial functional capabilities in relation to these elements and the ecological interactions that allow these microbes to thrive. Monte Cristo cave (MCC) - in Diamantina, Brazil - was chosen for this study. The cave is located in a region known for historic mining activity and occurrences of Mn and Fe-rich rocks (Costa et al. 2003). With that in mind, our main goal is to investigate if within the microbial community of MCC there is evidence of taxa and genes associated with Fe and Mn metabolism. The samples were collected in 2018 from walls and saprolite deposits within MCC. Community DNA from three samples, P1b, P3 and P7, were independently sequenced using Illumina shotgun sequencing, and the data were analysed using conventional metagenomic pipelines and in-house python scripts. Taxonomic classification was assessed using Kraken2; Fe related genes with FeGenie; and Mn related genes were predicted using BlastP against a collection of manually curated Mn-oxidizing proteins. Environmental Mn and Fe concentrations were measured using ICP-OES. Our results suggest the presence of a microbial community potentially able to change Fe and Mn redox states. In sites P1b and P7, genes associated to Fe and Mn oxidation were identified, Fig. 1. Taxonomic evidence for these metabolisms includes the presence of the taxa Comamonadaceae and Hyphomicrobiaceae, both families that were previously reported to harbour species able to oxidize Mn and Fe (Spring and Kämpfer 2015, Carmichael and Bräuer 2015). Our analysis also assigned contigs to the archaeal phyla Crenarchaeota, Euryarchaeota and Thaumarchaeota, whose presence has been associated with oligotrophic caves where archaea play a role in primary production (Ortiz et al. 2013) (Fig. 2). Moreover, the phylum Euryarchaeota harbours members that use Fe or Mn as electron acceptors during methane oxidation (Ettwig et al. 2016). Our results therefore contribute to understanding how microbial communities of MCC may be playing a role in the biogeochemical cycles of Fe and Mn under the conditions imposed by the subterranean environment, which might reflect similar processes in other caves yet to be explored by a metagenomics approach.","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ernest Chi Fru, Jérémie Aubineau, Olabode Bankole, Mohamed Ghnahalla, Landry Soh Tamehe, Abderrazak El Albani
Recently, two independent studies suggest that the emergence of putative fossilized macro-eukaryotes in the Paleoproterozoic Francevillian Basin, ~2.1 billion years ago, may be related to a rise in seawater Zn bioavailability. This explanation is reliant on their extraordinary high Zn content and association with light Zn isotopes characteristic of eukaryotic enrichment. However, the trigger and origin of rising seawater Zn supply to the basin remains unknown. This study unravels a transient episode of intense submarine hydrothermal activity that triggered the weathering of a nutrient-rich oceanic crust reservoir, related to the collision of the Congo-São Francisco cratons during the Eburnean-Transamazonian orogeny, as the source of abundant seawater dissolved Zn, together with a suite of essential trace metals and phosphate to the continental margin waters. Surprisingly, the initiation of hydrothermal weathering coincided with the rapid onset of a rare Paleoproterozoic seawater eutrophication event. This transition is marked by basin-wide redox stratification, high sediment loading with organic carbon (C org ) and nitrogen, elevated C/N ratios, a steep negative C org and positive bulk N isotope excursion, positive Ce anomalies, and low Mn/Fe ratios. Importantly, the transient eutrophication event ended with a reversal to lower seawater phosphate levels that coincided with rapid seawater ventilation and the appearance of macrofossil bearing sediments in Franceville. We suggest that these unexpected, localized conditions, set the stage for the emergence of the Francevillian biota.
{"title":"Emergence of the 2.1 Ga Francevillian biota was preceded by unprecedented hydrothermally driven seawater eutrophication","authors":"Ernest Chi Fru, Jérémie Aubineau, Olabode Bankole, Mohamed Ghnahalla, Landry Soh Tamehe, Abderrazak El Albani","doi":"10.3897/aca.6.e108014","DOIUrl":"https://doi.org/10.3897/aca.6.e108014","url":null,"abstract":"Recently, two independent studies suggest that the emergence of putative fossilized macro-eukaryotes in the Paleoproterozoic Francevillian Basin, ~2.1 billion years ago, may be related to a rise in seawater Zn bioavailability. This explanation is reliant on their extraordinary high Zn content and association with light Zn isotopes characteristic of eukaryotic enrichment. However, the trigger and origin of rising seawater Zn supply to the basin remains unknown. This study unravels a transient episode of intense submarine hydrothermal activity that triggered the weathering of a nutrient-rich oceanic crust reservoir, related to the collision of the Congo-São Francisco cratons during the Eburnean-Transamazonian orogeny, as the source of abundant seawater dissolved Zn, together with a suite of essential trace metals and phosphate to the continental margin waters. Surprisingly, the initiation of hydrothermal weathering coincided with the rapid onset of a rare Paleoproterozoic seawater eutrophication event. This transition is marked by basin-wide redox stratification, high sediment loading with organic carbon (C org ) and nitrogen, elevated C/N ratios, a steep negative C org and positive bulk N isotope excursion, positive Ce anomalies, and low Mn/Fe ratios. Importantly, the transient eutrophication event ended with a reversal to lower seawater phosphate levels that coincided with rapid seawater ventilation and the appearance of macrofossil bearing sediments in Franceville. We suggest that these unexpected, localized conditions, set the stage for the emergence of the Francevillian biota.","PeriodicalId":101714,"journal":{"name":"ARPHA Conference Abstracts","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maryam Rezaei Somee, Carolina González-Rosales, Stephanie Turner, Stefan Bertilsson, Mark Dopson, Maliheh Mehrshad
Deep groundwaters are among the most energy and nutrient-limited ecosystems on the planet. The limited resources are mainly due to the absence of photosynthesis-driven primary production (Kadnikov et al. 2020). These ecosystems do however host phylogenetically diverse and metabolically active microorganisms from all domains of life plus viruses (Holmfeldt et al. 2021, Mehrshad et al. 2021). In this study, we used a large metagenomic dataset generated over the last eight years from the Äspö Hard Rock Laboratory (Äspö HRL) in Sweden and drill holes in Olkiluoto Island, Finland. This dataset, termed the “Fennoscandian Shield Genomic Dataset” (FSGD), contains metagenome-assembled genomes (MAGs) and single-cell amplified genomes (SAGs). Previous studies on this dataset have shown that reciprocal symbiotic partnerships and efficiency of energy metabolism define the core microbiome of these deep groundwaters (Mehrshad et al. 2021). Studies on different marine and freshwater ecosystems show that oligotrophic environments host streamlined genomes with lower GC content. However, it is not known how the low carbon and energy availability in deep groundwaters affect the microbial community regarding their genome size and GC content. To address this, we used the FSDG to study the distribution of genome size and GC content among bacterial and archaeal genomes in Fennoscandian Shield deep groundwaters. We further disentangled the prevalent metabolic strategies in these genomes that is being used to support their carbon and nitrogen demands for replication and survival. A total of 1990 MAGs/SAGs with a completeness of ≥50% and <5% contamination were recovered from 43 metagenomic datasets. The taxonomy of the MAGs/SAGs was assigned using the GTDB-tk (Chaumeil et al. 2022) and the GC content and genome size of MAGs/SAGs were calculated. MAGs/SAGs were also functionally annotated to investigate the genome-encoded functional potential. To survey the preference for different metabolic pathways and metabolic cross-feeding, the C-fixation pathways were subdivided into 82 routes that lead to the production of intermediate compounds (e.g., formate, pyruvate, oxaloacetate, etc.). A similar analysis for nitrogen acquisition pathways and CO2-capturing enzymes was performed and the presence/absence of these metabolic modules was investigated in representative MAGs/SAGs from various deep groundwater types to explore the microbial community’s metabolic interaction. The GC content and estimated genome size (EGS) of the recovered MAGs/SAGs were linearly correlated, suggesting that higher genome-level GC content is associated with larger genome size. The most common taxa among high GC (≥50%) content MAGs/SAGs were affiliated with the phyla Proteobacteria, Desulfobacterota, Actinobacteriota, Chloroflexota, and Patescibacteria. Analysis of metabolic modules in the environmental context revealed that high GC content MAGs constituted the main primary producers in all investigated g
深层地下水是地球上能量和营养最有限的生态系统之一。有限的资源主要是由于缺乏光合作用驱动的初级生产(Kadnikov et al. 2020)。然而，这些生态系统确实承载了来自所有生命领域的系统发育多样性和代谢活跃的微生物以及病毒(Holmfeldt et al. 2021, Mehrshad et al. 2021)。在这项研究中，我们使用了瑞典Äspö硬岩实验室(Äspö HRL)在过去八年中生成的大型宏基因组数据集和芬兰Olkiluoto岛的钻孔。该数据集被称为“Fennoscandian Shield基因组数据集”(FSGD)，包含宏基因组组装基因组(MAGs)和单细胞扩增基因组(sag)。先前对该数据集的研究表明，互惠共生伙伴关系和能量代谢效率决定了这些深层地下水的核心微生物组(Mehrshad et al. 2021)。对不同海洋和淡水生态系统的研究表明，低营养环境承载流线型基因组，GC含量较低。然而，深层地下水的低碳和低能量如何影响微生物群落的基因组大小和GC含量尚不清楚。为了解决这个问题，我们利用FSDG研究了芬诺斯坎地盾深层地下水中细菌和古细菌基因组大小和GC含量的分布。我们进一步解开了这些基因组中普遍存在的代谢策略，这些代谢策略被用来支持它们对复制和生存的碳和氮需求。从43个宏基因组数据集中共恢复了1990个完整性≥50%和污染<5%的MAGs/ sag。使用GTDB-tk (Chaumeil et al. 2022)对MAGs/ sag进行分类，并计算MAGs/ sag的GC含量和基因组大小。我们还对MAGs/ sag进行了功能注释，以研究基因组编码的功能潜力。为了调查不同代谢途径和代谢交叉取食的偏好，将c固定途径细分为产生中间化合物(如甲酸酯、丙酮酸酯、草酰乙酸酯等)的82条途径。对氮获取途径和CO 2捕获酶进行了类似的分析，并在不同深层地下水类型的代表性MAGs/ sag中研究了这些代谢模块的存在/缺失，以探索微生物群落的代谢相互作用。GC含量与估算基因组大小(EGS)呈线性相关，表明GC含量越高，基因组大小越大。高GC(≥50%)含量的MAGs/ sag最常见的类群是Proteobacteria、Desulfobacterota、Actinobacteriota、Chloroflexota和Patescibacteria。环境代谢模块分析表明，在所有调查的地下水中，高GC含量的mag是主要的初级生产者。在研究的7条c固定途径中，导致还原性三羧酸(rTCA)中间体产生的途径在高gc含量基因组中显著富集。在GC含量高的mag中，羧基化/还原第一co2捕获酶均显著富集。在各种固碳策略中，rGly和rTCA是最节能的，分别消耗1个和3个ATP分子(Bar-Even et al. 2011)，这与rTCA在贫营养深层地下水中的高发生率相匹配。高GC含量的基因组具有代谢途径，可以生成合成嘌呤/嘧啶和氨基酸的关键前体。由于GC碱基对比AT碱基对多需要1个氮，因此GC含量高的原核生物按比例需要更多的氮来进行基因组复制。与此一致，来自FSGD的高GC含量的mag / sag具有额外的氮吸收系统，包括氨渗透酶和固氮基因。高GC含量的mag / sag似乎具有代谢多样性，能够通过不同的碳和氮固定途径获取营养，并通过各种清除c的策略来吸收底物，以获取能量并在少营养条件下生存。虽然它们更大的基因组大小和更高的GC含量需要更高的复制和维护费用，但它们在深部地下水群落中的存在得到了“黑皇后理论”的支持。根据这一理论，含有昂贵代谢途径的细胞在群落中得以维持，因为它提供了其他成员无法提供的服务。
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