• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1862-1867
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• 2008

Streptochlorin is a small molecule isolated from marine Streptomyces sp. that is known to have antiangiogenic and anticancer properties. In this study, we examined the effects of this compound on reactive oxygen species (ROS) production and the association of these effects with apoptotic tumor cell death, using a human hepatocarcinoma Hep3B cell line. The results of this study demonstrated that streptochlorin mediates ROS production, and that this mediation is followed by a decrease in the mitochondrial membrane potential (MMP, ${\Delta}{\Psi}_m$), activation of caspase-3, and downregulation of antiapoptotic Bcl-2 protein. The quenching of ROS generation by N-acetyl-L-cysteine administration, a scavenger of ROS, reversed the streptochlorin-induced apoptosis effects via inhibition of ROS production, MMP collapse, and the subsequent activation of caspase-3. These observations clearly indicate that ROS are involved in the early molecular events in the streptochlorin-induced apoptotic pathway. Taken together, our data imply that streptochlorin-induced ROS is a key mediator of MMP collapse, which leads to the caspase-3 activation, culminating in apoptosis.

• KSBB Journal
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• v.15 no.6
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• pp.600-604
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• 2000

Low density polyethylene(LDPE) film was fabricated with the addition of synthetic ceramic which contained a natural antimicrobial agents. The antimicrobial agents used were isolated from culture broths of methylotropic actinomycetes strains MO-16 and MO-17, and Streptomyces sp. No. 31, which was newly isolated from soils as an antifungal agent. Four-day old culture broth of Streptomyces sp. No. 31 showed strong antifungal activity against Aspergilus niger, a test strain, and retained antimicrobial activity after heat treatment at $121^{\circ}C$ for 15 min. The ceramic LDPE film reduced the growth of total aerobic bacteria in packaged minced pork compared with commercial film. The film revealed a 40 to 50% growth inhibition of E. coli on a contained agar plate. In the storage testing of various packaged foods at room temperature for 30 days, the ceramic LDPE film showed excellent preservation compared with commercial film.

• Journal of Microbiology and Biotechnology
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• v.33 no.11
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• pp.1437-1447
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• 2023

A recently bioinformatic analysis of genomic sequences of fungi indicated that fungi are able to produce more secondary metabolites than expected. Despite their potency, many biosynthetic pathways are silent in the absence of specific culture conditions or chemical cues. To access cryptic metabolism, 108 fungal strains isolated from various sites were cultured with or without Streptomyces sp. 13F051 which mainly produces trichostatin analogues, followed by comparison of metabolic profiles using LC-MS. Among the 108 fungal strains, 14 produced secondary metabolites that were not recognized or were scarcely produced in mono-cultivation. Of these two fungal strains, Myrmecridium schulzeri 15F098 and Scleroconidioma sphagnicola 15S058 produced four new compounds (1-4) along with a known compound (5), demonstrating that all four compounds were produced by physical interaction with Streptomyces sp. 13F051. Bioactivity evaluation indicated that compounds 3-5 impede migration of MDA-MB-231 breast cancer cells.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.96.2-97
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• 2003

More than 1200 microorganisms were isolated from soil samples collected from various sources and localities. Among the isolates, 2 actinomyces (TH-04 and BA313) and 1 Bacillus sp. (CJ3) were selected as antagonists to pepper anthracnose fungus Colletotrichum gloeosporioides. These 3 isolates inhibitied mycelial growth of C gloeosporioides and the inhibition rates were over 70％ on PDA. When the isolates were co-cultured with conidia of C. gloeosporioides in potato dextrose broth, conidial germination was severely inhibited and the inhibition rates of TH-04, BA313, and CJ3 at 24 hours were 75％, 72％, and 68％, respectively. The inhibition rates at n hours incubation were not much different from the rates at 24 hours. To check the activity on the plant, each isolate was mixed with equal volume of conidial suspension of C. gloeosporioides and wound-inoculated on green pepper fruit. After 6 days, the anthracnose lesions on the fruits inoculated with the mixture were much smaller than the lesions caused by the C. gloeosporioides itself. The lesion areas of TH-04 or BA313 treated pepper were less than 30％ of the check. TH-04 and BA313 also showed antagonistic activity to Phytophthora spp. and Botrytis cinerea. By scanning electron microscopy and fatty acid analyses (MIDI), TH-04 and BA313 were identified to Streptomyces halstedii and S. violaceusniger, repectively.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.316-321
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• 1993

MCH-201 was isolated from the mycelium of Streptomyces sp. Ba16 as a potent effector on proliferation and morphology of human breast tumor cell line, MCF-7. Morphological change could be observed at concentration between 2.5${\mu}$g/ml and 250pg/ml and showed cytotoxic effect at the concentration of more than 5${\mu}$g/ml. This compound also showed inhibitory effect on DNA synthesis of hepatoma cells, Hepa 1c1c7, and strong cytotoxic effect on proliferation of human tumor cell lines, A549 and XF498.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.129-137
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• 2007

During the screening of material which has the antimicrobial activity against aminoglycoside-resistant bacteria, A new material ${\varepsilon}-(L-{\beta}-lysine)$ polypeptide from a culture medium of Streptomyces sp.(DWGS2) was isolated, and the structure and the physicochemical properties of the new material were elucidated. The new material was separated by column chromatography of the culture medium using Dowex $1{\times}2$, Silica gel, and Sephadex LH20 etc. The structure and molecular weight were determined with the data of NMR, MALDI mass, and ESI mass experiments. And the monomer obtained by hydrolysis of the new material with 6N-HCI was identified as a $L-{\beta}-lysine(T_2)$, which is a tail of bleomycin. As tail-region analogy, $T_2({\beta}-lysine$ derivatives from streptomyces) interactions with a self-complementary oligonucleotides, $d(CGCTTCGAAGCG)_2$, was investigated by NMR.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2006.04a
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• pp.77-90
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• 2006

Beta-amyloid peptide (A$\beta$) is a major component of senile plaques and its aggregation is considered to play a critical role in pathogenesis of Alzheimer's disease (AD). Aggregation of A$\beta$ could result from both increased synthesis and decreased degradation of A$\beta$. Our laboratory is interested in understanding the mechanism of A$\beta$ degradation in brain. Recently our laboratory identified a bacterial gene (SKAP) from Streptomyces sp KK565 whose protein product has an activity to cleave A$\beta$ and thus reduce the A$\beta$-induced neurotoxicity. The sequence analysis showed that this gene was closely related to aminopeptidase. Maldi-Tof analysis showed that the recombinant SKAP protein expressed in E. coli cleaves both A$\beta$ 40 and A$\beta$ 42 at the N-terminal of A$\beta$ while an aminopeptidase from Streptomyces griseus (SGAP) cleaves at the C-terminal. We also identified a mammalian homolog of SKAP and the recombinant mammalian protein expressed in Sf-9 insect cells showed a similar proteolytic activity to SGAP, cutting A$\beta$ at the C-terminus. I well discuss the detailed mechanism of the enzyme action and its functional implication in AD.

• Molecules and Cells
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• v.22 no.2
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• pp.154-162
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• 2006

The entire gene cluster involved in the biosynthesis of angucyclines Sch 47554 and Sch 47555 was cloned, sequenced, and characterized. Analysis of the nucleotide sequence of genomic DNA spanning 77.5-kb revealed a total of 55 open reading frames, and the deduced products exhibited strong sequence similarities to type II polyketide synthases, deoxysugar biosynthetic enzymes, and a variety of accessory enzymes. The involvement of this gene cluster in the pathway of Sch 47554 and Sch 47555 was confirmed by genetic inactivation of the aromatase, including a portion of the ketoreductase, which was disrupted by inserting the thiostrepton gene.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1076-1080
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• 2008

Glucagon, a peptide hormone produced by alpha-cells of Langerhans islets, is a physiological antagonist of insulin and stimulator of its secretion. In order to improve its bioactivity, we modified its structure at the C-terminus by amidation catalyzed by a recombinant amidase in bacterial cells. The human gene coding for glucagon-gly was PCR amplified using three overlapping primers and cloned together with a rat ${\alpha}$-amidase gene in plasmid pMGA. Both genes were expressed under control of the strong constitutive promoter of aph and secretion signal melC1 in Streptomyces lividans. With Phenyl-Sepharose 6 FF, Q-Sepharose FF, SP-Sepharose FF chromatographies and HPLC, the peptide was purified to about 93.4% purity. The molecular mass of the peptide is 3.494 kDa as analyzed by MALDI TOF, which agrees with the theoretical mass value of the C-terminal amidated glucagon. The N-terminal sequence of the peptide was also determined, confirming its identity with human glucagon at the N-terminal part. ELISA showed that the purified peptide amide is bioactive in reacting with glucagon antibodies.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.303-309
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• 2012

Keratinases are of particular interest because of their action on insoluble keratins and generally on a broad range of protein substrates. Alkalophilic and neutrophilic actinomycete strains isolated from different soil samples, rich in keratinaceous substances were screened for keratinolytic activity. An alkalophilic isolate, TBG-S13A5, was found to possess good keratinolytic activity and was able to utilize feather as the sole carbon and nitrogen source. TBG-S13A5 exhibited an off-white aerial mass color with a rectus-flexibilis type of spore chain. The morphological, microscopical and biochemical characters were comparable with that of Streptomyces albidoflavus. Fatty acid methyl ester profiling (FAME) and 16S rDNA sequence analysis confirmed its identity as a strain of S. albidoflavus. Under submerged fermentation conditions, maximum protease production was recorded on the $5^{th}$ day of incubation at $30^{\circ}C$, using basal broth of pH 9.0 with 0.25% (w/v) white chicken feather. This strain could affect feather degradation when the initial pH was 8 and above and maximum protease production was recorded when the initial pH was around 10.5. The effectiveness of the crude enzyme in destaining and leather dehairing were also demonstrated.