Membrane-associated hexavalent chromium reductase of Bacillus megaterium TKW3 with induced expression

TY - JOUR

T1 - Membrane-associated hexavalent chromium reductase of Bacillus megaterium TKW3 with induced expression

AU - Cheung, K. H.

AU - Lai, H. Y.

AU - Gu, Ji Dong

PY - 2006/6

Y1 - 2006/6

N2 - Hexavalent chromium (Cr6+) is a highly harmful pollutant, which can be detoxified and precipitated through reduction to Cr3+. Bacillus megaterium TKW3 previously isolated from chromium-contaminated marine sediments was capable of reducing Cr6+ in concomitance with metalloids (Se4+, Se6+, and As5+). Notwithstanding approximately 50% inhibition, it was the first report of simultaneous bacterial reduction of Cr6+ and Se4+ (to elemental Se). No significant difference was observed among electron donors (glucose, maltose, and mannitol) on Cr6+ reduction by B. megaterium TKW3. The reduction was constitutive and determined to be non-plasmid mediated. Peptide mass fingerprints (PMF) revealed a novel aerobic membrane-associated reductase with Cr6+-induced expression and specific reductive activity (in nmol Cr6+/mg protein/min) of 0.220 as compared with 0.087 of the soluble protein fraction. Respiratory inhibitor NaN3 did not interfere with the reductase activity. Transmission electron microscopy with energy dispersive X-ray (TEM-EDX) analysis confirmed the aggregation of reduced chromium along the intracellular membrane region. Future identification of the N-terminal amino acid sequence of this reductase will facilitate purification and understanding of its enzymatic action.

AB - Hexavalent chromium (Cr6+) is a highly harmful pollutant, which can be detoxified and precipitated through reduction to Cr3+. Bacillus megaterium TKW3 previously isolated from chromium-contaminated marine sediments was capable of reducing Cr6+ in concomitance with metalloids (Se4+, Se6+, and As5+). Notwithstanding approximately 50% inhibition, it was the first report of simultaneous bacterial reduction of Cr6+ and Se4+ (to elemental Se). No significant difference was observed among electron donors (glucose, maltose, and mannitol) on Cr6+ reduction by B. megaterium TKW3. The reduction was constitutive and determined to be non-plasmid mediated. Peptide mass fingerprints (PMF) revealed a novel aerobic membrane-associated reductase with Cr6+-induced expression and specific reductive activity (in nmol Cr6+/mg protein/min) of 0.220 as compared with 0.087 of the soluble protein fraction. Respiratory inhibitor NaN3 did not interfere with the reductase activity. Transmission electron microscopy with energy dispersive X-ray (TEM-EDX) analysis confirmed the aggregation of reduced chromium along the intracellular membrane region. Future identification of the N-terminal amino acid sequence of this reductase will facilitate purification and understanding of its enzymatic action.

KW - Bacillus megaterium

KW - Bioremediation

KW - Chromate reductase

KW - Metalloid

KW - Proteomics

KW - Selenium

UR - http://www.scopus.com/inward/record.url?scp=33745617675&partnerID=8YFLogxK

M3 - 文章

AN - SCOPUS:33745617675

SN - 1017-7825

VL - 16

SP - 855

EP - 862

JO - Journal of Microbiology and Biotechnology

JF - Journal of Microbiology and Biotechnology

IS - 6

ER -