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A rhizosphere-associated symbiont, Photobacterium spp. strain MELD1, and its targeted synergistic activity for phytoprotection against mercury.

Mathew DC, Ho YN, Gicana RG, Mathew GM, Chien MC, Huang CC - PLoS ONE (2015)

Bottom Line: While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer.The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots.The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R. O. C.

ABSTRACT
Though heavy metal such as mercury is toxic to plants and microorganisms, the synergistic activity between them may offer benefit for surviving. In this study, a mercury-reducing bacterium, Photobacterium spp. strain MELD1, with an MIC of 33 mg x kg(-1) mercury was isolated from a severely mercury and dioxin contaminated rhizosphere soil of reed (Phragmites australis). While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer. The efficiency of MELD1 to vaporize mercury (25 mg x kg(-1), 24 h) and its tolerance to toxic metals and xenobiotics such as lead, cadmium, pentachlorophenol, pentachloroethylene, 3-chlorobenzoic acid, 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin is promising. Combination of a long yard bean (Vigna unguiculata ssp. Sesquipedalis) and strain MELD1 proved beneficial in the phytoprotection of mercury in vivo. The effect of mercury (Hg) on growth, distribution and tolerance was examined in root, shoot, leaves and pod of yard long bean with and without the inoculation of strain MELD1. The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots. Biolog plate assay were used to assess the sole-carbon source utilization pattern of the isolate and Indole-3-acetic acid (IAA) productivity was analyzed to examine if the strain could contribute to plant growth. The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.

No MeSH data available.


Related in: MedlinePlus

MELDI, MELD2 and MELD3 were grown in LB medium having a known concentration of 25 mg. kg-1 HgCl2.Mercury/MA- 2000 (AAS) was used to detect the mercury reductase activity of the strains. Bars plot mean ± SD of three replicate experiments.
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pone.0121178.g003: MELDI, MELD2 and MELD3 were grown in LB medium having a known concentration of 25 mg. kg-1 HgCl2.Mercury/MA- 2000 (AAS) was used to detect the mercury reductase activity of the strains. Bars plot mean ± SD of three replicate experiments.

Mentions: The three Photobacterium strains were able to volatilize elevated levels of mercuric chloride from a high concentration of HgCl2. The mercury reductase activity of MELD1, MELD2 and MELD3 were noted for a period of 24 h with concentration of 25 mg. kg-1respectively. This concentration was used as a standard concentration, as it was determined all the 3 strains could grow at this concentration. The strain MELD1 was able to reduce 96% of Hg to a residual concentration of 0.90 mg. kg-1. This result suggested that although all the three strains could reduce the Hg2+ to Hg0, MELD1 significantly enhanced the reduction of Hg2+ in a controlled environment (Fig. 3).


A rhizosphere-associated symbiont, Photobacterium spp. strain MELD1, and its targeted synergistic activity for phytoprotection against mercury.

Mathew DC, Ho YN, Gicana RG, Mathew GM, Chien MC, Huang CC - PLoS ONE (2015)

MELDI, MELD2 and MELD3 were grown in LB medium having a known concentration of 25 mg. kg-1 HgCl2.Mercury/MA- 2000 (AAS) was used to detect the mercury reductase activity of the strains. Bars plot mean ± SD of three replicate experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376707&req=5

pone.0121178.g003: MELDI, MELD2 and MELD3 were grown in LB medium having a known concentration of 25 mg. kg-1 HgCl2.Mercury/MA- 2000 (AAS) was used to detect the mercury reductase activity of the strains. Bars plot mean ± SD of three replicate experiments.
Mentions: The three Photobacterium strains were able to volatilize elevated levels of mercuric chloride from a high concentration of HgCl2. The mercury reductase activity of MELD1, MELD2 and MELD3 were noted for a period of 24 h with concentration of 25 mg. kg-1respectively. This concentration was used as a standard concentration, as it was determined all the 3 strains could grow at this concentration. The strain MELD1 was able to reduce 96% of Hg to a residual concentration of 0.90 mg. kg-1. This result suggested that although all the three strains could reduce the Hg2+ to Hg0, MELD1 significantly enhanced the reduction of Hg2+ in a controlled environment (Fig. 3).

Bottom Line: While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer.The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots.The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R. O. C.

ABSTRACT
Though heavy metal such as mercury is toxic to plants and microorganisms, the synergistic activity between them may offer benefit for surviving. In this study, a mercury-reducing bacterium, Photobacterium spp. strain MELD1, with an MIC of 33 mg x kg(-1) mercury was isolated from a severely mercury and dioxin contaminated rhizosphere soil of reed (Phragmites australis). While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer. The efficiency of MELD1 to vaporize mercury (25 mg x kg(-1), 24 h) and its tolerance to toxic metals and xenobiotics such as lead, cadmium, pentachlorophenol, pentachloroethylene, 3-chlorobenzoic acid, 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin is promising. Combination of a long yard bean (Vigna unguiculata ssp. Sesquipedalis) and strain MELD1 proved beneficial in the phytoprotection of mercury in vivo. The effect of mercury (Hg) on growth, distribution and tolerance was examined in root, shoot, leaves and pod of yard long bean with and without the inoculation of strain MELD1. The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots. Biolog plate assay were used to assess the sole-carbon source utilization pattern of the isolate and Indole-3-acetic acid (IAA) productivity was analyzed to examine if the strain could contribute to plant growth. The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.

No MeSH data available.


Related in: MedlinePlus