• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.984-988
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• 2003

The actinomycete strain KH-6l4 possessed strong antifungal activity, especially antagonistic to the rice blast fungus, Pyricularia oryzae. Diaminopimelic acid (DAP) type and morphological and physiological characteristics, examined by scanning electron microscopy (SEM), indicated that KH-614 belonged to the genus Streptomyces. Antifungal agent produced by this strain was found to be most active, when the strain was cultured in the presence of glucose, polypeptone, and yeast extract (PY) medium for 6 days at $27^{\circ}C$. Based on the spectral report data, MS and NMR, the antifungal agent was identified as cyclo(L-leucyl-L-prolyl). According to the antimicrobial activity test measured by minimal inhibitory concentration (MIC), the cyclo(1eu-pro) exhibited the activity against Candida albicans IAM 4905, Mucor ramannianus IAM6218, Rhizoctonia solani IFO 6218, Aspergilus fumigatus ATCC 42202, Glomerella cingulata IFO 9767, Trichophton mentagrophytes ATCC 18749, and Trichophyton rubrum ATCC 44766, the order of MIC values were 50, 12.5, 5, 50, 25, 5, $5\;\mu\textrm{g}/ml$, respectively. Specifically, cyclo(1eu-pro) was one of the most effective elements against Pyricularia oryzae IFO 5994 with the MIC value of $2.5\;\mu\textrm{g}/ml$, thus indicating that cyclo(leu-pro) is a potential antifungal agent.

• Microbiology and Biotechnology Letters
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• v.10 no.4
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• pp.283-288
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• 1982

Trypsin inhibitor produced by Streptomyces sp. was investigated its reactive characteristics against trypsin. The mode of inhibition against trypsin was mixed type of non-competitive and competitive with casein, and enzyme-inhibitor complex was formed rapidly. The inhibitory activity was increased by the addition of isoleucine and depressed by silver, mercuric or cupric ion. And when egg albumin or hemoglobin was used as substrate for trypsin, the inhibition ratio was changed. The inhibitor inhibited coagulation of blood of bovine.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.764-770
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• 2006

Dihydrochalcomycin (GERI-155), produced by Streptomyces sp. KCTC-0041BP isolated from Korean soil, is a 16-membered macrolide antibiotic consisting of two deoxysugar moieties at C-5 and C-20 positions of a branched lactone ring. The cloning and sequencing of a gene cluster for dihydrochalcomycin biosynthesis revealed a 63-kb nucleotide region containing 25 open reading frames (ORFs). The products of all of these 25 ORFs playa role in dihydrochalcomycin biosynthesis and self-resistance against the compounds synthesized. At the core of this cluster lies a 39.6-kb polyketide synthase (PKS) region encoding eight modules in five giant multifunctional protein-coding genes (gerSI-SV). The genes responsible for the biosynthesis of deoxysugar moieties, D-chalcose and D-mycinose, and their modification and attachment were found on either side of this PKS region. The involvement of this gene cluster in dihydrochalcomycin biosynthesis was confirmed by disruption of the dehydratase (DH) domain in module 3 of the PKS gene and by metabolite analysis.

• Archives of Pharmacal Research
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• v.20 no.4
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• pp.372-374
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• 1997

In order to develop new anti-inflammatory agents having different action mechanisms compared with nonsteroidal and steroidal anti-inflammatory drugs, the culture broths of various actinomycetes isolated from soil were screened using an in vivo mouse ear edma assay and one strain (Streptomyces sp. MT 2705-4: KCTC 8651 P) was selected. Activity-guided purification led to the isolation of a polyether compound, dianemycin. Topically, dianemycin showed a potent anti-inflammatory activity in mouse ear edema induced by croton-oil or arachidonic acid.$ED_{50}$value of dianemycin was found to be 0.8 mg,/ear compared to 0.4 mg/ear of prednisolone in croton-oil ear edema. However, dianemycin did not show the inhibitory activity in UV-erythema and delayed hypersensitivity reaction. These results indicate that dianemycin is a potential topical anti-inflammatory agent.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.447-452
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• 1994

The strain SL-387 which produces new inhibitors of aminopeptidase M, MR-387A and B, was isolated from a soil sample. The strain has branched substrate mycelia, from which aerial hyphae develop in the form of open spirals. Spore surface is smooth. Melanoid and soluble pigme- nts were observed. The isolate contains LL-diaminopimelic acid in its cell wall hydrolysate, and has no pectinolytic activity. The strain SL-387 is closely related to Streptomyces griseoruber and S. naganishii, but is different from these strains in some cultural and physiological characteristics. This strain was, therefore, designated as Streptomyces sp. SL-387. The effects of several carbon and nitrogen sources on the production of the inhibitor were examined. Among them, glucose, galactose, mannose, and xylose were effective as a carbon source and soybean meal, soytone, fish meal, and gluten meal were effective as a nitrogen source. The maximum peak of the inhibitor production in jar fermentor was obtained on the fifth day of culture.

• Mycobiology
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• v.37 no.3
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• pp.211-214
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• 2009

An actinomycete strain was isolated from northern part of Bangladesh and identified as a new Streptomyces species on the basis of its morphological, biochemical, cultural characteristics and 16S rRNA data. Attempts were made to optimize the culture conditions for the production of antimicrobial metabolites by this strain. Antimicrobial metabolites production was started after 7 days of incubation of culture broth and reached its maximum levels after 10 days and thereafter gradually decreased. The maximum production of antimicrobial metabolites was obtained when the culture medium pH was adjusted to 8. The optimum temperature for antimicrobial metabolites production was $39^{\circ}C$, indicated the new strain as mesophilic organism. Basel medium supplemented with glucose and yeast extract as carbon and nitrogen sources, respectively, was proved to be the best for the production of bioactive metabolites. Maximum production of bioactive metabolites was when NaCl concentration was 1% and among different minerals tested, $K_2HPO_4$ and NaCl showed positive influence on antibiotic production by the strain.

• Journal of Microbiology and Biotechnology
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• v.7 no.6
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• pp.402-408
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• 1997

The antibiotic-producing strain HW-003 was screened from soil and found to be effective against the multidrug-resistant Staphylococcus aureus. The spore chain of HW-003 was retinaculiaperti, and the spore surface was spiny. Strain HW-003 has a LL-diaminopimelic acid isoform in the cell wall. The aerial mass color of the strain was gray, and the reverse side was yellow-brown. The strain produced melanin, but did not produce soluble pigments. According to the Taxon program, HW-003 showed best match with Streptomyces cyaneus. Antibiotic production reached a maximum after 72-h cultivation. The antibiotic was purified with silica gel column chromatography, octadecylsilyl column chromatography, and HPLC. The purified antibiotic, AMRSA1, showed strong inhibitory activity against multidrug-resistant Staphylococcus aureus and gram-positive bacteria. The molecular weight of AMRSA1 was about 1, 100. AMRSA1 was a peptide antibiotic containing alanine and serine.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1299-1306
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• 2022

Six ansamycin derivatives were isolated from the culture broth of Streptomyces sp. KCB17JA11, including four new hygrolansamycins A-D (1-4) and known congeners divergolide O (5) and hygrocin C (6). Compounds 1-5 featured an unusual six-membered O-heterocyclic moiety. The isolation workflow was guided by a Molecular Networking-based dereplication strategy. The structures of 1-4 were elucidated using NMR and HRESIMS experiments, and the absolute configuration was established by the Mosher's method. Compound 2 exhibited mild cytotoxicity against five cancer cell lines with IC₅₀ values ranging from 24.60 ± 3.37 µM to 49.93 ± 4.52 µM.

• Microbiology and Biotechnology Letters
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• v.4 no.4
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• pp.145-151
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• 1976

Cultural characteristics of a strain of Streptomyces sp. K-14 (KFCC 35051) producing glucose isomerase were demonstrated. The glucose isomerase was produced when the strain was grown in the medium containing pure xylan or xylan.containing materials such as wheat bran or com cob. The optimum condition was attained in a culture medium composed of 3 % wheat bran or com cob, 2 % com steep liquor, 0.1% $MgSO_4$$7H_2O$ and 0.012 % $CoSO_4$$7H_2O$ for the production of the glucose isomera,e. The production of the enzyme reached to a maximum level when the strain was cultured for 40 hrs $30^{\circ}C$ and pH 7.0.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.101-110
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• 2021

Interactions between microalgae and heterotrophic bacteria are common in natural environments. This study investigated the effect of heterotrophic bacteria on the activity of the photosynthetic eukaryotic alga Chlorella sp. MF1907 when cocultured. A total of 31 heterotrophic bacterial isolates belonging to different genera were cocultured with MF1907. Interactions of the alga with Agromyces, Rhodococcus, Sphingomonas, Hyphomicrobium, Rhizobium, and Pseudomonas were positive, while those with Burkholderia, Paraburkholderia, Micrococcus, Arthrobacter, Mycobacterium, Streptomyces, Pedobacter, Mucilaginibacter, Fictibacillus, Tumebacillus, Sphingopyxis, and Erythrobacter were negative (p < 0.05). A turnover experiment demonstrating a switch from heterotrophic to autotrophic activity of MF1907 was performed using 16 isolates exhibiting apparent effects (positive, negative, or neutral). Compared with the results of the coculture experiment, eight isolates exhibited the same outcomes, while the others did not. Consistently, Pseudomonas and Agromyces showed a remarkable positive effect on MF1907 activity, and Burkholderia, Streptomyces, and Erythrobacter had a marked negative effect. Our results suggest that it may be possible to use the isolates for controlling populations of microalgae in natural and engineered environments.