Polyphosphate produced in recombinant<i>Escherichia coli</i>confers mercury resistance

Pan-Hou, Hidemitsu; Kiyono, Masako; Omura, H.; Omura, Tomoko; Endo, Ginro

doi:10.1111/j.1574-6968.2002.tb11045.x

Cited by 47 publications

(22 citation statements)

References 30 publications

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“…These results support that polyP is capable of reducing the accumulated mercury probably via chelation formation mechanism. 9,10) In a preliminary experiment, we found mercury remained in the soils after 1 week culture of transgenic tobacco was reduced to about 40% of the added mercury (data not shown). This observation, together with the fact that the concentration of heavy metals in plant roots is at least 10-times greater than those in shoots 18) suggest that overexpression of ppk-specified polyP in transgenic plants may provide an ecologically compatible approach for phytoremediation of mercury pollution.…”

Section: Discussionmentioning

confidence: 99%

“…2). 9,10) Due to chelation formation with polyP, the transported Hg 2ϩ was never free in the plant tissues, and the transgenic tobacco, therefore, expressed a resistant phenotype to Hg 2ϩ . The Hg 2ϩ resistant phenotype shown by transgenic tobacco may make it feasible to extract and accumulate mercury form mercurial-polluted sites.…”

Section: Discussionmentioning

confidence: 99%

“…6,7) In a previous paper, we demonstrated for the first time that ppk-specified polyP is able to reduce the cytotoxicity of Hg 2ϩ probably via chelation formation between polyP and Hg 2ϩ , and confers bacterial accumulation of mercury without largely taxing the cells. 9,10) Recently, we reported that expression of bacterial PolyP in genetically engineered tobacco also confers tobacco more resistant to mercury. 12) This trait noted for the engineered tobacco seems able to work as valuable tool for environmental phytoremediation of mercury.…”

Section: Discussionmentioning

confidence: 99%

“…9,10) From these results we communicated that expression of ppk-specific polyP in transgenic tobacco may provide an ecologically compatible approach for environmental phytoremediation of mercury pollution in soils. However, the feasibility of ppk-specific polyP for phytoremediation of mercury had not uncovered.…”

mentioning

confidence: 93%

“…[9][10][11] In theory, plants engineering expression of polyP would also reduce mercury toxicity and accumulate more mercury from the polluted sites. As expected, we found that tobacco plant genetically engineered to express bacterial polyP was more resistant to Hg 2ϩ than its wild-type progenitors.…”

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confidence: 99%

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Accumulation of Mercury in Transgenic Tobacco Expressing Bacterial Polyphosphate

Nagata

Ishikawa

Kiyono

et al. 2006

Biological & Pharmaceutical Bulletin

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Mercury pollution is a worldwide problem in environments, resulting primarily from its industrial use in bleaching operations, as a catalyst, as a pigment in paints, and in the mining of gold. The effects of this heavy metal on the ecosystem and human health are growing concerns. Decontamination of mercury in the sediment and soil around industrial plants has been a challenge for a long time. Unfortunately, numerous sites contaminated with mercurials have not been remediated because of the high costs of dredging and landfilling.2) Phytoremediation, using plants to extract and/or sequester mercurials, is often regarded as a relatively inexpensive and efficient way of cleaning up the mercury-contaminated sites.Recently, with advances in biotechnology, phytoremediation utilizing specific plants to remove mercurials from contaminated sites has become one of the most rapidly developing fields for environmental restoration. Several studies have successfully integrated bacterial mer-genes into plant genome to create superior plants for phytoremediation of mercurial contaminated sites, based on the merA-mediated mercury reduction and volatilization mechanism.3-8) However, phytovolatilization of mercurials mediated by bacterial merA gene from the polluted sites would still cause public anxiety because of the release of mercury vapor into the ambient air that will redistribute in the ecosphere and be recycled to environment. To help solve this environmental problem, a new mercury-scavenging mechanism that can be expressed in plant cells and accumulate mercury from contaminated sites without releasing mercury vapor into the ambient air is required in place of the merA-mediated mercury reduction mechanism.In the previous papers, we reported that expression of ppkspecified polyphosphate (polyP) in a genetically engineered Escherichia coli strain resulted in significantly increased the bioaccumulation of Hg 2ϩ from simulated and actual wastewaters, and protected the bacterial cells from the toxic accumulated Hg 2ϩ . [9][10][11] In theory, plants engineering expression of polyP would also reduce mercury toxicity and accumulate more mercury from the polluted sites. As expected, we found that tobacco plant genetically engineered to express bacterial polyP was more resistant to Hg 2ϩ than its wild-type progenitors.12) The transported Hg 2ϩ seemed to be converted to a less toxic molecule, probably via chelation formation with ppk-specific polyP in the tobacco tissues just as the fact previously described in a bacterial system. 9,10) From these results we communicated that expression of ppk-specific polyP in transgenic tobacco may provide an ecologically compatible approach for environmental phytoremediation of mercury pollution in soils. However, the feasibility of ppk-specific polyP for phytoremediation of mercury had not uncovered. In this study, the ability of ppk-transgenic tobacco to accumulate mercury from the contaminated sites was investigated and the feasibility of this engineered tobacco for environmental remediation of ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%