| Research Abstract |
A P (3HB)-degrading bacterium Marinobacter sp. was isolated from deep sea. A P (3HB) depolymerase produced by the isolate was purified from the culture supernatant and characterized in detail. Further, a gene encoding the enzyme was cloned in E. coli. Genetic analysis revealed that the enzyme is composed of three functional domains, that is, catalytic, linker, and substrate-binding domains. Fungal P (3HB) depolymerase was purified from the supernatant of Penicillium funiculosom. A cDNA encoding the enzyme was cloned. Genetic analysis revealed that the enzyme lacks the substrate-binding domain (SBD) in contrast to bacterial enzymes. Due to the deletion, the fungal enzyme had less binding ability than those of bacterial enzymes. Homology search of the depolymerase genes showed that fungal enzyme gene may be incorporated from the degrading bacterial strain by the horizontal gene transfer. Mesophilic poly (ethylene succinate) (PESu)-degrading strains were isolated from natural environments, and identified. It was found that the degrading species belong to Gram-positive bacterium and fungus.
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