| Summary: | 碩士 === 文化大學 === 生物科技研究所 === 83 === Pseudomonas sp. are aggressive colnizers of the rhizophere of
various crops and some of them have a broad spectrum of
antagonistic activity against plant pathogens.Then production
of antifungal compounds has been regarded of the main
mechanisms involved in antagonism. One of the antifungal
compounds, named pyrrolnitrin, has been proved to be the key
antibiotic in controlling fungal pathogens in vitro and in soil
environments. Pyrrolnitrin is a phenylpyrrole antibiotic with a
wide range of antifungal activity. It causes mycelial
deformities and inhibition of conidiation in phytopathogenic
fungi. However it is readily decomposed by the U.V. irradiation
because of the existence of such a chemically unstable moiety
as pyrrol ring in its molecule. Based on the reasons mentioned
above, we consider it is necessary to protect pyrrolnitrin from
U.V. damage in developing a longer-lasting Pseudomonas-type
biofungicide. Firstly, the coding sequence of mel gene was
successfully subcloned to an Escherchia coli plasmid, pGEM-3Z,
and the mel gene could express well by using the SP6 promoter
of pGEM-3Z. When harboring the plasmid pYHL-694 bearing mel
gene, E.coli JM109 can produce melanin pigment after 24 hours
incoubated at 37℃ on TYT medium. Finally, we have successfully
transferred the mel gene to the pseudomonads by using the brosd-
host-range plasmid,RSF1010; however, the expression of mel gene
in the microorganism did not observed yet.
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