• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.846-852
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• 2003

rpoB DNAs (279 bp) from 34 species of 5 actinomycete genera were sequenced and a phylogenetic tree was constructed based on the sequences obtained. The genera were clearly differentiated in the rpoB tree, forming clades specific to their respective genus. In addition, 2 signature amino acid residues specific to Streptomyces were found in a multiple alignment of the deduced amino acid sequences. To empirically confirm that this rpoB gene analysis system could be used to differentiate actinomycete isolates, the proposed system was used to identify 16 actinomycete isolates from Jeju Island. All isolates were successfully differentiated into the genera Streptomyces and Micromonospora. Accordingly, this is the first report that an rpoB sequence analysis has been effectively used to differentiate actinomycete strains at the genus level.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1741-1746
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• 2008

This study was conducted to select endophytic actinomycetes as biocontrol agents against Chinese cabbage clubroot caused by Plasmodiophora brassicae. A total of 81 endophytic actinomycetes were isolated from surface-sterilized roots of Chinese cabbage that was grown on paddy field and upland soils collected from various locations in Korea. By using 16S ribosomal DNA (rDNA) gene sequencing, they were classified to 8 actinobacterial genera. The genus Microbispora (67%) was most frequently isolated, followed by Streptomyces (12%) and Micromonospora (11%). Three of the 81 isolates, when inoculated in germinated Chinese cabbage seeds and then transplanted to pots, effectively suppressed the occurrence of a post-inoculated strain of P. brassicae in the pots. They showed control values of 58% for strain A004, 33% for strain A011, and 42% for strain A018. Based on cell wall components, morphological characteristics, and phylogenetic analyses, the three antagonistic isolates were identified as Microbispora rosea subsp. rosea (A004 and A011) and Streptomyces olivochromogenes (A018). Further researches on the field efficacy and action modes of the three actinomycetes are in progress.