• Microbiology and Biotechnology Letters
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• v.24 no.3
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• pp.327-330
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• 1996

An amino acid antimetabolite named YS-460 was isolated from the culture filtrate of a newly isolated Actinomycetes identified as Streptomyces sp. Fermentation was carried out in the synthetic medium at 30$\circ$C for 5 days. Purification was done by ion exchange resin, active carbon, silica gel column chromatography and obtained 38 mg of pure active substance per liter of the broth. YS-460, an amino acid like substance, has the molecular formula of C$_{7}$H$_{11}$NO$_{3}$- Its structure determined to be furanomycin by spectral analysis. It is active against some bacteria on a chemically defined medium and reversed competitively by L-isoleucine and non-competitively by L-leucine and L-valine.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.242-248
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• 2011

Several soil bacteria were found to degrade N-Acylhomoserine lactones (NAHLs), thereby interfering with the bacterial quorum sensing system. In this research, fifteen strains of NAHL degrading rhizobacteria were isolated from potato rhizosphere. Based on phenotypic characteristics and 16S rDNA sequence analyses, the strains were identified as members of genera Bacillus, Streptomyces, Arthrobacter, Pseudomonas and Mesorhizobium. All tested isolates were capable to degrade both synthetic and natural NAHL produced by Pectobacterium carotovorum subsp. carotovorum (Pcc) strain EMPCC. In quorum quenching experiments selected isolates, especially Mesorhizobium sp., were markedly reduced the pathogenicity of Pcc strain EMPCC in potato tubers and totally suppressed tissue maceration on potato tubers. These led to consider the latter as a useful biocontrol agent against Pectobacterium spp.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.158-162
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• 2006

Cyclic dipeptides isolated from Streptomyces sp. have been shown to have antimicrobial activity as well as other potentially useful biological activities. The purpose of this study was to compare the in vitro activity of two cyclic dipeptides combined against anaerobic bacteria with the activity of other antimicrobial agents. Specifically, the in vitro activity of the combination of two cyclic dipeptides was investigated against 140 clinical isolates of anaerobic bacteria by the agar dilution method and was compared with that of erythromycin, cefoxitin, imipenem, clindamycin, and metronidazole. The cyclic dipeptide combination and imipenem were the most active antimicrobial agents tested. In addition, the cyclic dipeptide combination had a radioprotective effect on five normal human lung fibroblast cells, showing survival rates higher $(>90\%)$ than either of the two cyclic dipeptides alone $(<80\%)$.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.11-20
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• 2020

Quercetin and its derivatives are important metabolites that belong to the flavonol class of flavonoids. Quercetin and some of the conjugates have been approved by the FDA for human use. They are widely distributed among plants and have various biological activities, such as being anticancer, antiviral, and antioxidant. Hence, the biosynthesis of novel derivatives is an important field of research. Glycosylation and methylation are two important modification strategies that have long been used and have resulted in many novel metabolites that are not present in natural sources. A strategy for modifying quercetin in E. coli by means of glycosylation, for example, involves overexpressing respective glycosyltransferases (GTs) in the host and metabolic engineering for increasing nucleoside diphosphate sugar (NDP-sugar). Still others have used microorganisms other than E. coli, such as Streptomyces sp., for the biotransformation process. The overall study of the structural activity relationship has revealed that modification of some residues in quercetin decreased one activity but increased others. This review summarizes all of the information mentioned above.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.105-110
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• 2002

The sequence of 3,221 nucleotides immediately adjacent to rpsA gene encoding 30S ribosomal protein S1 of Brevibacterium ammoniagenes was determined. A putative open reading frame (ORF) of 2,670 nucleotides for a polypeptide of 889 amino acid residues and a TAG stop codon was found, which is located at a distance of 723 nucleotides upstream from rpsA gene with same translational direction. The deduced amino acid sequence of the ORF was found to be highly homologous to the DNA polymerase I of Streptomyces griseus (75.48％), Rhodococcus sp. ATCC 15963 (56.69％), Mycobacterium tuberculosis (55.46％) and Mycobacterium leprae (53.99％). It was suggested that the predicted product of the ORF is a DNA polymerase I with three functional domains. Two domains of 5 → 3 exonuclease and DNA polymerase are highly conserved with other DNA polymerase I, but 3 → 5 exonuclease domain is less conserved.

• Korean Journal of Microbiology
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• v.18 no.2
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• pp.59-66
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• 1980

Two strains S-P and S-P-2, both Streptomyces sp., have been isolated and were found to have relatively high specific enzyme activity compared to other organisms reported. The specific activity of the enzyme produced from these two strains were 0.25 and 0.2 international units respectively. The productivity of the enzyme achieved was about 50 IU/l/hr. Glucose isomerase form these strains was found to be stable under the temperature of heat treatment (at $65^{\circ}C$) for fixation of enzyme inside the dell. This organism has an advantage in that it did not require toxic metalic ion for enzyme activity and could utilize xylan in leu of xylose as an inducer. The optimal temperature and pH of enzymatic reaction purpose of using these data for the optimal operation and designing of enzyme reactor system. The reaction mechanism was found to follow the single substrate reversible reaction kinetics. The kinetic constants determined experimentally are : $K_{mf}=0.33M,\;K_{mb}=1.0M,\;V_{mf}=0.88{\mu}mole\;per\;min.,\;V_{mb}= 2.96{\mu}mole\;per\;min.\;and\;K_{eq}=0.74.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.297-303
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• 1995

Antitumor antibiotic material was produced by Streptomyces sp. YBE-316 which was isolated from soil, and the optimal culture conditions for the antitumor antibiotic material production were as follows; 2.0% (w/v) sucrose, 0.8% (w/v) polypeptone, 0.4% (w/v) yeast extract, 0.2% (w/v) K$_{2}$HPO$_{4}$, pH 7.0, at 30$\circ$C, 150 rpm and for 100 hours culture. The antitumor antibiotic material had strong antitumor antibiotic activities against most testing tumor cell lines, gram positive and negative bacteria, yeasts, and, especially, Penicillium chrysogenum in fungi.

• Journal of Microbiology and Biotechnology
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• v.3 no.1
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• pp.51-56
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• 1993

The structure of herbicidal compound, 3D5, isolated from the culture broth of Streptomyces sp. 3D5, was elucidated as a 16-membered diene macrolide by the spectroscopic method. It was identical with bafilomycin D which has been known to be an insecticidal compound and an inhibitor of $K^{+}-dependent$ ATPase. However, this is the first report which shows that bafilomycin D has a herbicidal activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.35-40
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• 2000

The effect of levanheptaose produced by levanase from Streptomyces sp. 366L on principle intestinal microflora was investigated. The reaction product, levanheptaose, was used as a carbon source for various intestinal microflora. As a results, Bifidobacterium adolescentis, Lactobacillus acidophilus, and Eubacterium limosum grew effectively in the in vitro experiment, whereas Clostridium perfringens, E. coli, and Staphylococcus aureus did not. Therefore levanheptaose seems to promote selectively the growth of B. adolescentis and L. acidophilus. In the in vivo experiment, the effect of levanheptaose on the growth of intestinal microflora, $\beta$-fructosidase activity, pH, and butyrate concentration were examined in rats. Apparently, the number of fecal Bifidobacteria, the amount of butyrate, and $\beta$-fructosidase activity were increased, whereas total aerobes and pH were reduced in rats fed by levanheptaose diets, compared with those of control diets. We concluded that those effects may be beneficial in improving gastrointestinal health.

• YAKHAK HOEJI
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• v.35 no.3
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• pp.245-251
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• 1991

Selective culture of actinomycetes from soil microbes and their antibiotic producing characters by agar-disk method were examined. Some of the organisms which produced antibiotics on agar disk did not produce antibiotics in liquid culture. Further examination indicated that production of antibiotic was dependent on the composition of medium. Many streptomycestes produced antibacterial substances in tryptic soy broth but others produced antifungal antibiotics in V-8 broth. Production of antibacterial substances by Streptomyces sp. was also dependent on the medium composition.