| Budget Amount *help |
¥11,060,000 (Direct Cost: ¥10,400,000、Indirect Cost: ¥660,000)
Fiscal Year 2007: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2005: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Research Abstract |
Currently, research on the biodegradation of recalcitrant chemicals is mainly concentrated on microorganisms isolated from soils and activated sludge. Studies on marine bacterial genes and enzymes involved in biodegradation of xenobiotics such as carbazole and dioxins are very rare. However, accidents caused by damage to tankers, or the inflow of recalcitrant molecules from rivers, have created pollution in seas that requires environmental remediation.
The concentration of bacteria in the sea is very low, and it is very difficult to culture these bacteria because quantities of trace elements present in the seawater affect the growth of marine bacteria. To overcome of these problems, it is necessary to concentrate the seawater to enable bacterial screening. By manipulating the composition of the isolation medium, we succeeded in isolating organisms from seawater that can degrade carbazole and dibenzofuran. We isolated new bacterial carbazole degraders, classified as Lysobacter sp. strain
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s OC6 and OC7, which show very low homology to reported bacteria and probably belong to a new order.
To obtain genes from these marine bacteria that may be involved in the degradation of carbazole, genes from soil bacterial enzymes participating in the degradation of carbazole were used as a probe for Southern hybridization, but no hybridization was achieved. Using the shotgun cloning method, we successfully obtained the genes from marine bacteria that are involved in the degradation of recalcitrant compounds.
The meta-cleavage enzyme involved in the degradation of carbazole and dibenzofuran consists of two subunits, but the three-dimensional (3D) structure of the enzyme is not yet established. However, this information is required to elucidate the 3D structure of the enzymes in order to construct new enzymes that have new substrate specificities and high activity. The meta-cleavage enzyme from Pseudomonas resinovorans CA10, which has two subunits, was purified and crystallized, and the 3D structure was established by the SIRS method. Elucidation of the 3D meta-cleavage enzyme structure of marine bacterial strains is now in progress. These results will be used to construct enzymes with new substrate specificities and activities by comparing the enzymes of terrestrial and marine bacteria. Less
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