|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1999 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1998 : ¥2,400,000 (Direct Cost : ¥2,400,000)
Mercury released in the environment is of increasing concern. Input of mercury to the environment can be prevented by treating industrial and anthropogenic wastes before discharge. Several chemical systems have been utilized to remove mercury from waste water. The present study aims to develop a new biocatalysts for mercury remediaation.
The nature, organization, DNA sequence and physiological function of the mercury resistant operon (mer operon) on the Pseudomonas K-62 plasmid pMR26 were first investigated. We found that the pMR26 carries two mer operons. One of them has been shown to consist of a merR followed by an o/p and then by merT, merP, merA, merG, and merB. The second operon consists of a merR followed by an o/p and then by merB and merD. We also showed that the new gene merG is involved in the phenylmercury resistance, presumably by reducing in cell permeability to phenylmercury. The merT and merP of pMR26 were found to be involved in the transport of not only HgィイD12+ィエD1 but also CィイD26ィエD2HィイD25ィエD2HgィイD1+ィエD1 into the cells.
Based on the results obtained, a fusion plasmid pMK27 which contained merR-o/p-merT-merP and ppk (polyphosphate kinase gene) was constructed for removal of mercury in the environment. We found the fusion genes are inducibly expressed when the cells were induced by mercurials. In addition, the cells with pMK27 tookup more mercury the cells without the plasmid. These results suggest that the transported mercury by merT-merP may be chelated by ppk-specified polyphosphate. The application of pMK27 in the remediation of mercury in the polluted environment is now imminent.
以上の研究成果はJ. Bacteriol., 181, 726-730 (1999)、Biol. Pharm. Bull., 22, 910-914 (1999)、Biol. Pharm. Bull., 23, 279-282 (2000)およびJ. Health Sci., 46, In press (2000)に公表した。