• The Plant Pathology Journal
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• v.20 no.2
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• pp.110-114
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• 2004

Through in vitro screening for biocontrol agents (BCAs) against Streptomyces scabiei causing potato (Solanum tuberosum) common scab, 19 streptomycete and 17 fungal isolates with antagonistic activity were selected as BCA candidates. For the selection of BCA candidates which are highly resistant to 10 kinds of antibiotics or pesticides, chemical susceptibility testing was initially performed in vitro. A remarkable degree of variation in susceptibility to antibiotics or pesticides was observed among the isolates tested. Streptomycete A020645 isolate was highly resistant to all the tested chemicals except neomycin up to 5,000 ppm. On the other hand, out of 36 antagonistic microbes subjected to in vivo pot tests using cultivar Daejima, four streptomycete isolates namely, A020645, A010321, A010564, and A020973, showed high antagonistic activity with >60% and 55% control value, respectively, and high chemical resistance to 10 kinds of chemicals. Therefore, these isolates were selected as potential BCAs for the control of potato common scab.

• Journal of Microbiology
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• v.40 no.2
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• pp.178-181
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• 2002

Streptomycete isolator strain M0137 showed cytotoxic effect on THP-1 cells. One of the purified substances produced from the strain was identified as nonadecanoic acid. Morphological and physiological properties, phylogenetic analysis, and genomic fingerprinting of strain M0137 were determined. Strain M0137 showed a high similarity with Streptomyces scabiei, phenotypically and phylogenetically. In contrast, genomic fingerprinting and G+C content analysis revealed that strain M0137 could be distinguished from S. scabiei ATCC49173$\^$T/. We propose to name strain M0137 as Streptomyces scabiei Subsp.

• Korean Journal of Microbiology
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• v.27 no.1
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• pp.56-62
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• 1989

Antagonistic effects of Streptomyces species aganinst Fusarium solani causing ginseng root rot were investigated in terms of chitinase activity and growth inhibition in vitro. Among 131 isolates of streptomycetes obtained from ginseng cultivating soil, 9 isolates producing large clear zone around the colony on a chitin agar medium were selected for further study. All 9 isolates produced chitinase in a range from 0.10 to 0.38 U lysing cells of F. solani and inhibited germination of the conidia. In the ten-fold condentrated culture filtrate of S. alboniger ST59 and S. roseolilacinus ST129, the number of conidia of F. solane was reduced to about 20% of original count within 14 days. When S. alboniger ST59 and F. solani were grown simultaneously in the mineral saly medium, chitinase activity increased with incubation period, whereas mycelial volume of F. solani decreased. In a chitin added mineral salt medium, chitinase activity increased during the first four days and maintained steady level until the 8th day, and increased thereafter. S. alboniger ST59 lysed mycelia, conidia and even chlamydospores of F. solani. It is probable that the antagonistic activity of this streptomycete against F. solani is the lysis of fungal cell wall by streptomycete producing chitinase affected by antifungal substances.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.59.2-59
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• 1999

No Abstract, See Full Text

• YAKHAK HOEJI
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• v.28 no.2
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• pp.89-95
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• 1984

Microorganisms having beta-latamase inhibitory activity were selected from soil samples collected from 63 spots throughout the country. Screening procedures consist of two steps. Those are growth inhibition test of penicillinase-producing Staphylococcus aureus by double-layered agar plate containing penicillin G as a substrate, and that of penicillin sensitive Staphylococcus aureus ATCC 6538 in the similiar condition including penicillinase. Finally, a strain was selected from a soil sample of Pa-ju, Kyeong-gi Do. This strain was classified as a Streptomyces sp. by ISP(International Streptomycete Project) and Bergey's manual.

• Microbiology and Biotechnology Letters
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• v.13 no.1
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• pp.93-101
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• 1985

Much of the progress in genetic engineering has been accomplished by employing Escherichia coli as the host organism. For many reasons, however, some other organisms have greater potential as alternatives to E. coli. In particular, streptomycetes are attractive organisms as hosts especially for the producation of various secondary metabolites such as antibiotics. In this article, therefore, we reviewed the techniques for development of vector system and expression of genes for antibiotic biosynthesis in streptomycete hosts.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.534-539
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• 1996

Total 276 soil actinomycete strains were isolated from 46 soil samples collected at domestic natural caves; the Kosu, Chundong, and Nodong caves at Chungbook province, the Kossi cave at Kangwon province, the Sungruye cave at Kyungbook province, the Hyupjae, Ssangyong, and Manjang caves at Cheju province. All of these isolates were identified to the genus level based on morphological and physiological characteristics. As the result, 52.5% of those isolates were Streptomyces, 16.3% were Micromonospora, 22.8% were Nocardioform group, 1.1% were Actinomadura, 0.3% were Nocardiopsis, 0.3% were Streptosporangium, 0.3% were Nocardioides, 1.4% were Kineosporia, 4.7% were the others. Streptomycete strains were the most abundant, but were relatively less comparing to general distribution pattern. Nocardioform and Micromonospora strains were quite abundant, and other rare actinomycete groups were somewhat abundant comparing to general distribution pattern previously reported. Especially Nocardioform strains were highly abundant at almost of the natural caves.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.149-153
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• 1998

From soils seasonally collected at two depths (0~2 cm, $50{\pm}1cm$) of forest, field, grass land, or paddy field, distinct strains of actinomycetes were isolated and identified to the genus level. The genus-diversity of soil actinomycetes was revealed to be considerably different by seasonal change. It was also affected by soil depths, soil types, or actinomycete groups. At the soil depth of 0~2 cm, the seasonal distribution fluctuation (%) of streptomycete strains was higher in grass land (41%), field (39%) soil than paddy field (18%), or forest (18%), whereas that of streptomycete strains at the soil depth of $50{\pm}1cm$ was high in order of paddy field (36%), field (28%), grass land (26%), and forest (16%). On the other hand, the seasonal distribution fluctuation ratio of rare actinomycete strains at the soil depth of 0~2 cm was above 45% except for paddy field (26%). At the soil depth of $50{\pm}1cm$, the seasonal distribution of rare actinomycete strains exhibited high fluctuation (%) in order of forest (79%), paddy field (36%), field (24%), and grass land (10%).

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1787-1795
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• 2015

The transition from primary to secondary metabolism in antibiotic-producing Streptomyces correlates with expression of genes involved in stress responses. Consequently, regulatory pathways that regulate specific stress responses are potential targets to manipulate to increase antibiotic titers. In this study, genes encoding key proteins involved in regulation of the osmotic stress response in Streptomyces avermitilis, the industrial producer of avermectins, are investigated as targets. Disruption of either osaB_Sa, encoding a response regulator protein, or osaC_Sa, encoding a multidomain regulator of the alternative sigma factor SigB, led to increased production of both oligomycin, by up to 200%, and avermectin, by up to 37%. The mutations also conditionally affected morphological development; under osmotic stress, the mutants were unable to erect an aerial mycelium. In addition, we demonstrate the delivery of DNA into a streptomycete using biolistics. The data reveal that information on stress regulatory responses can be integrated in rational strain improvement to improve yields of bioactive secondary metabolites.

• Journal of Microbiology
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• v.45 no.1
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• pp.6-10
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• 2007

Culture broth of a streptomycete isolate, Streptomyces sp. CS684 showed antibacterial activity on methicilin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE). Among purified substances from the organism, CSU-1, which is active against MRSA and VRE, is a $C_{37}H_{62}O_{12}Na\;(M^+,721.3875)$, and identified as laidlomycin. The anti-MRSA and anti-VRE activity of CSU-1 was stronger than oxacillin and vancomycin. Phylogenetic analysis showed that strain CS684 is very similar to Streptomyces ardus NRRL $2817^T$, whereas the ability of Streptomyces sp. CS684 to produce laidlomycin was shown to be unique.