Cheok Heng Pang

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The Tn3-like Streptomyces transposon Tn4560 was used to mutagenize Streptomyces avermitilis, the producer of anthelmintic avermectins and the cell growth inhibitor oligomycin. Tn4560 transposed in this strain from a temperature-sensitive plasmid to the chromosome and from the chromosome to a plasmid with an apparent frequency of about 10(-4) to 10(-3) at(More)
Streptomyces avermitilis produces the anthelmintic and insecticidal secondary metabolite avermectins. Following mutagenesis of a recombinant strain, S. avermitilis K2038 (aveD X) with N-methyl-N'-nitro-N-nitrosoguanidine, a derivative strain K2057 (aveD aveE X), was isolated, which produced seven avermectin-related compounds different from the eight(More)
Most microbial secondary metabolites are producec as complexes of closely related compoundsby theii producing organisms. The avermectins1*, milbemycins2 and nemadectins3~5) are typical examples produced ii such a manner. The milbemyciif complex is known t( consist of more than twenty components6 ~ 8), however only a few are commercial products. A rationale(More)
6,8a-deoxy derivatives of avermectins produced by a mutant strain of Streptomyces avermitilis K20571} derived by mutation from strain K2038 producing avermectins B l a and B2a selectively2). The parent strain K2038 carries two types of mutations, C-5 0-methylation (aveD) and the selective incorporation of branched-chain fatty acid into the avermectin(More)
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