Expression of mercuric reductase from Bacillus megaterium MB1 in eukaryotic microalga Chlorella sp. DT: an approach for mercury phytoremediation.
A eukaryotic microalga, Chlorella sp. DT, was transformed with the Bacillus megaterium strain MB1 merA gene, encoding mercuric reductase (MerA), which mediates the reduction of Hg2+ to volatile elemental Hg0. The transformed Chlorella cells were selected first by hygromycin B and then by HgCl2. The existence of merA gene in the genomic DNA of transgenic strains was shown by polymerase chain reaction amplification, while the stable integration of merA into genomic DNA of transgenic strains was confirmed by Southern blot analysis. The ability to remove Hg2+ in merA transgenic strains was higher than that in the wild type. The merA transgenic strains showed higher growth rate and photosynthetic activity than the wild type did in the presence of a toxic concentration of Hg2+. Cultured with Hg2+, the expression level of superoxide dismutase in transgenic strains was lower than that in the wild type, suggesting that the transgenic strains faced a lower level of oxidative stress. All the results indicated that merA gene was successfully integrated into the genome of transgenic strains and functionally expressed to promote the removal of Hg2+.
Huang
Chieh-Chen
CC
Department of Life Sciences, National Chung-Hsing University, Tai-Chung 40227, Taiwan.
Chen
Meng-Wei
MW
Department of Life Sciences, National Chung-Hsing University, Tai-Chung 40227, Taiwan.
Hsieh
Ju-Liang
JL
Department of Life Sciences, National Chung-Hsing University, Tai-Chung 40227, Taiwan.
Lin
Wen-Hao
WH
Department of Life Sciences, National Chung-Hsing University, Tai-Chung 40227, Taiwan.
Chen
Pei-Chung
PC
Department of Life Sciences, National Chung-Hsing University, Tai-Chung 40227, Taiwan.
Chien
Lee-Feng
LF
Department of Life Sciences, National Chung-Hsing University, Tai-Chung 40227, Taiwan. lfchien@dragon.nchu.edu.tw.
D001410:Bacillus megaterium / Q000201:enzymology*; D001673:Biodegradation, Environmental; D015139:Blotting, Southern; D002708:Chlorella / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000032:analysis; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D015870:Gene Expression; D017669:Mercury Compounds / Q000378:metabolism* / Q000633:toxicity; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000378:metabolism; D010088:Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013482:Superoxide Dismutase / Q000032:analysis
D004269:DNA, Bacterial; D017669:Mercury Compounds; D011994:Recombinant Proteins; D002734:Chlorophyll; D010088:Oxidoreductases; D013482:Superoxide Dismutase; C021551:mercuric reductase