| 项目编号: | 1349366
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| 项目名称: | Ecology and biogeochemical cycling of photosynthetic arsenite-oxidizing bacteria |
| 作者: | Chad Saltikov
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| 承担单位: | University of California-Santa Cruz
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| 批准年: | 2013
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| 开始日期: | 2014-04-15
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| 结束日期: | 2018-03-31
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| 资助金额: | USD299824
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | photosynthetic bacterium
; arsenite
; bacterium
; arsenic
; photosynthetic purple sulfur bacterium
; microbial ecology
; arsenic rich environment
; microbial ecology study
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| 英文摘要: | This project will investigate a new branching point within the complex arsenic biogeochemical cycle referred to as anoxygenic photosynthetic arsenite oxidation. During this process, bacteria catalyze light-dependent oxidation of arsenite to arsenate. Little is known about the biological basis and environmental significance of arsenite-fueled photosynthesis. There are numerous environments where this process may be occurring such as in terrestrial hot springs, shallow water thermal vents, lake and stream euphotic zones, and crop soils irrigated with arsenite rich ground water, for example in Bangladesh. Because arsenite is considered a more toxic and hydrologically mobile form of arsenic, the oxidation of arsenite by photosynthetic bacteria could provide an important means for natural attenuation of arsenic toxicity within surface waters impacted by arsenic. The project aims are to determine the abundance, diversity, and activity of arsenite oxidizing anoxygenic photosynthetic bacteria in arsenic rich environments. The central hypothesis is that arsenic-dependent photosynthetic bacteria utilize a 'novel' arsenite oxidase enzyme called ArxA that can also be used to indicate their presence and arsenic-transforming activity in arsenic rich environments. The hypothesis will be tested by: (i) isolating and characterizing new photosynthetic arsenite oxidizers from arsenic rich environments in various hydro/geothermal features around the Mono Lake, CA area, (ii) measuring photosynthetic arsenite oxidation rates in Big Soda Lake, an arsenic rich lake in Nevada that has a seasonal bloom of photosynthetic purple sulfur bacteria, and (iii) conducting microbial ecology studies in Big Soda Lake aimed at quantifying arsenite oxidase gene (arxA) abundance vs. depth and correlating this data to the arsenic biogeochemistry. Results from this project will lead to the isolation of new photosynthetic arsenite oxidizing organisms, new methods for quantifying light-dependent arsenite oxidation in environmental samples, and the development of molecular-based tools that target the key genes associated with light-driven arsenite-oxidation.
Arsenic is mostly a naturally-occurring water pollutant affecting the health of millions of people worldwide. Increasing our understanding of how arsenic changes and moves in the environment from which humans obtain important resources like water and food has potential implications for the mitigation of risk from this toxic element. Microbes can play a key role in changing the chemistry of arsenic, which in turn strongly affects arsenic's mobility and toxicity. This study focuses upon a recently-discovered form of microbial arsenic metabolism, specifically examining photosynthetic bacteria that change arsenite (more toxic form) to arsenate (less toxic form) in anoxic (oxygen-depleted) environments. Microbial ecology and environmental chemistry studies will be conducted to determine the activities of these photosynthetic arsenic oxidizing bacteria. The results will provide important insight regarding how these newly identified microbes may impact the complex arsenic biogeochemical cycle. In addition, understanding arsenite-based anoxygenic photosynthesis (doesn't generate oxygen like standard photosynthesis) may provide insight regarding the evolution of early forms of photosynthesis. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/97092
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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| Recommended Citation: | |
Chad Saltikov. Ecology and biogeochemical cycling of photosynthetic arsenite-oxidizing bacteria. 2013-01-01.
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