Accumulation and Transformation of Arsenic in the Blue-Green Alga Synechocysis sp. PCC6803

Yin, Xixiang; Wang, L. H.; Bai, Ren; Huang, Hai; Sun, Guoxin

doi:10.1007/s11270-011-0936-0

Cited by 94 publications

(60 citation statements)

References 25 publications

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“…Our results indicated that As(III) oxidation was mediated by fresh cyanobacterial cells, because neither dead cells ( Figure S1) nor cyanobacterial excretion had any effect on it, 5 and Figure 3. Arsenic species (▲, As(III); ■ , As(V); ○, sum of different As species) in medium with Synechocystis sp.…”

Section: ■ Discussionmentioning

confidence: 71%

Cyanobacteria-Mediated Arsenic Redox Dynamics Is Regulated by Phosphate in Aquatic Environments

Zhang

Rensing

Zhu

2013

Environ. Sci. Technol.

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Studies of cyanobacteria in environments where arsenic (As) and phosphate (P) both occur in significant concentrations have so far only focused on the effect of P on As(V) toxicity and bioaccumulation, with little attention to the influence of P on As redox transformations. Our study revealed that As(III) oxidation by Synechocystis appeared to be more effective with increased P levels. We demonstrated that the higher As(III) percentage in the medium under P-limited conditions was due to enhanced As(V) uptake and the subsequent efflux of intracellularly reduced As(III) which in turn contributed to higher As(III) concentrations in the medium. Arsenic redox changes by Synechocystis under P-limited conditions is a dynamic cyclic process that includes the following: surface As(III) oxidation (either in the periplasm or near the outer membrane), As(V) uptake, intracellular As(V) reduction, and As(III) efflux. These observations not only expand our understanding of how P influences microbial As redox metabolisms but also provide insights into the biogeochemical coupling between As and P in As contaminated eutrophic aquatic environments and artificial wetland-paddy fields. ■ INTRODUCTIONArsenic (As) is a ubiquitous toxic substance broadly distributed in the environment. 1 The transport and transformation of As in environment are governed by geochemical and biological processes, generating an As biogeochemical cycle. 2 Microbially mediated biotransformations may play an important role in determining As biogeochemistry and toxicity in various natural ecosystems, especially As redox processes which influence the two most abundant inorganic As forms (arsenite As(III) and arsenate As(V)) in the environment. 3 Thus it is essential to understand microbial As redox metabolisms to make further advances in As bioremediation.Microalgae are desirable organisms for As remediation in contaminated water because of their high surface area to volume ratios. 4 Studies have shown that microalgae can tolerate high levels of As and biotransform it in several ways to detoxify it. 5−9 Considering the complex living environments of microalgae, many factors could affect As biotransformations by microalgae. Phosphate (P) is one of the most significant determinants of microalgal growth. Due to its structural similarity with As(V), 10 the influence of P on microbial As metabolisms has been extensively studied and primarily focused on As(V) accumulation and toxicity. 11,12 Besides affecting As(V) uptake, P can further influence the subsequent As detoxification process, i.e. As(V) reduction. 13,14 In the bacteria Agrobacterium tumefaciens str. 5B, it has been reported that As(V) reduction was completely suppressed at elevated levels of P (500 and 1000 μM), but the expression of the As(V) reductase gene (arsC) was not inhibited by high P concentrations. 15 As(III) oxidation and the Phosphorus (Pi) concentration were reported to be tightly and intimately coregulated in the soil bacterium Agrobacterium tumefaciens. 16 However, when analyzing ...

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Section: ■ Discussionmentioning

confidence: 71%

Cyanobacteria-Mediated Arsenic Redox Dynamics Is Regulated by Phosphate in Aquatic Environments

Zhang

Rensing

Zhu

2013

Environ. Sci. Technol.

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“…This is similar to the response of other cyanobacteria, such as Synechocystis sp. PCC6803 (Yin et al, 2011), which oxidizes As(III) to As(V) for detoxification. Moreover, S. platensis showed the ability of As(III) methylation after a long-time As(III) exposure.…”

Section: Discussionmentioning

confidence: 99%

“…CK treatments (1 μmol/L As(III) without bacteria) were placed under the same conditions. Trimethylarsenite (TMA(III)) released from cyanobacteria was collected as reported previously (Yin et al, 2011). As species was determined to investigate biotransformation of As, and the extraction method of cellular As was performed as described before (Yan et al, 2015).…”

Section: Organisms and Cultivationsmentioning

confidence: 99%

Arsenic methylation by an arsenite S-adenosylmethionine methyltransferase from Spirulina platensis

Guo

Xue

Yan

et al. 2016

Journal of Environmental Sciences

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Arsenic-contaminated water is a serious hazard for human health. Plankton plays a critical role in the fate and toxicity of arsenic in water by accumulation and biotransformation.Spirulina platensis (S. platensis), a typical plankton, is often used as a supplement or feed for pharmacy and aquiculture, and may introduce arsenic into the food chain, resulting in a risk to human health. However, there are few studies about how S. platensis biotransforms arsenic. In this study, we investigated arsenic biotransformation by S. platensis. When exposed to arsenite (As(III)), S. platensis accumulated arsenic up to 4.1 mg/kg dry weight.After exposure to As(III), arsenate (As(V)) was the predominant species making up 64% to 86% of the total arsenic. Monomethylarsenate (MMA(V)) and dimethylarsenate (DMA(V)) were also detected. An arsenite S-adenosylmethionine methyltransferase from S. platensis (SpArsM) was identified and characterized. SpArsM showed low identity with other reported ArsM enzymes. The Escherichia coli AW3110 bearing SparsM gene resulted in As(III) methylation and conferring resistance to As(III). The in vitro assay showed that SpArsM exhibited As(III) methylation activity. DMA(V) and a small amount of MMA(V) were detected in the reaction system within 0.5 hr. A truncated SpArsM derivative lacking the last 34 residues still had the ability to methylate As(III). The three single mutants of SpArsM (C59S, C186S, and C238S) abolished the capability of As(III) methylation, suggesting the three cysteine residues are involved in catalysis. We propose that SpArsM is responsible for As methylation and detoxification of As(III) and may contribute to As biogeochemistry.

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“…High level of arsenic in water poses a great risk to animals, plants and human health Yin et al 2012). The flooded paddy fields create a reducing environment or oxidative stress and accumulate high levels of As III (Meharg et al 2009).…”

Section: Heavy Metals Toxicity On Biological Systemsmentioning

confidence: 99%

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

Mani

Kumar

2013

Int. J. Environ. Sci. Technol.

514

137

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The ability of heavy metals bioaccumulation to cause toxicity in biological systems-human, animals, microorganisms and plants-is an important issue for environmental health and safety. Recent biotechnological approaches for bioremediation include biomineralization (mineral synthesis by living organisms or biomaterials), biosorption (dead microbial and renewable agricultural biomass), phytostabilization (immobilization in plant roots), hyperaccumulation (exceptional metal concentration in plant shoots), dendroremediation (growing trees in polluted soils), biostimulation (stimulating living microbial population), rhizoremediation (plant and microbe), mycoremediation (stimulating living fungi/mycelial ultrafiltration), cyanoremediation (stimulating algal mass for remediation) and genoremediation (stimulating gene for remediation process). The adequate restoration of the environment requires cooperation, integration and assimilation of such biotechnological advances along with traditional and ethical wisdom to unravel the mystery of nature in the emerging field of bioremediation. This review highlights better understanding of the problems associated with the toxicity of heavy metals to the contaminated ecosystems and their viable, sustainable and eco-friendly bioremediation technologies, especially the mechanisms of phytoremediation of heavy metals along with some case studies in India and abroad. However, the challenges (biosafety assessment and genetic pollution) involved in adopting the new initiatives for cleaning-up the heavy metals-contaminated ecosystems from both ecological and greener point of view must not be ignored.

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Accumulation and Transformation of Arsenic in the Blue-Green Alga Synechocysis sp. PCC6803

Cited by 94 publications

References 25 publications

Cyanobacteria-Mediated Arsenic Redox Dynamics Is Regulated by Phosphate in Aquatic Environments

Cyanobacteria-Mediated Arsenic Redox Dynamics Is Regulated by Phosphate in Aquatic Environments

Arsenic methylation by an arsenite S-adenosylmethionine methyltransferase from Spirulina platensis

Biotechnological advances in bioremediation of heavy metals contaminated ecosystems: an overview with special reference to phytoremediation

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