• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.176-180
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• 2000

Three polyene macrolide antibiotics including two new compounds were isolated from the culture mycelia of a Streptomyces species. The structures of these metabollites were determined as elizabethin, a previously reported 28-membered macrolide and two analohs, using combined spectroscopic methods. These compounds exhibited antifungal activity and cytotoxicity against a juman leukemia cell.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.212-215
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• 2004

In order to develop a biocontrol agent that can effectively control Fusarium wilt on Cymbidium genus, the effectiveness of antagonistic microbes against the cause pathogen was screened. The selected microbe showed a broad spectrum of antifungal activity, and the culture broth of this microbe had better preventive effect on Fusarium wilt than the commercial chemical agent in the pot assay. This isolated strain, GBA-12, was identified as Streptomyces kasugaensis, and the antifungal substance was purified from a broth culture of GBA-12. This purified substance was identified as a polyene macrolide (YS-822A) that was newly discovered from Streptomyces kasugaensis, and it exhibited antifungal activity against several phytopathogenic fungi.

• The Plant Pathology Journal
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• 제35권4호
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• pp.341-350
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• 2019

Streptomyces padanus PMS-702 strain produces a polyene macrolide antibiotic fungichromin and displays antagonistic activities against many phytopathogenic fungi. In the present study, experimental formulations were assessed to improve the production of fungichromin, the efficacy of PMS-702 on the suppression of sporangial germination, and the reduction of cucumber downy mildew caused by Pseudoperonospora cubensis. PMS-702 strain cultured in a soybean meal-glucose (SMG) medium led to low levels of fungichromin accumulation and sporangial germination suppression. Increasing medium compositions and adding plant oils (noticeably coconut oil) in SMG significantly increased fungichromin production from 68 to $1,999.6{\mu}g/ml$. Microscopic examination reveals that the resultant suspensions significantly reduced sporangial germination and caused cytoplasmic aggregation. Greenhouse trials reveal that the application of PMS-702 cultural suspensions reduced downy mildew severity considerably. The addition of Tween 80 into the synthetic medium while culturing PMS-702 further increased the suppressive efficacy of downy mildew severity, particularly when applied at 24 h before inoculation or co-applied with inoculum. Fungichromin at $50{\mu}g/ml$ induced phytotoxicity showing minor necrosis surrounded with light yellowish halos on cucumber leaves. The concentration that leads to 90% inhibition (IC90) of sporangial germination was estimated to be around $10{\mu}g/ml$. The results provide a strong possibility of using the S. padanus PMS-702 strain as a biocontrol agent to control other plant pathogens.

• 한국미생물·생명공학회지
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• 제32권3호
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• pp.238-242
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• 2004

D. bryoniae를 원인균으로 하는 참외 만고병에 대해서 항만고병 활성물질을 생산하는 미생물을 방선균으로부터 선별 분리한 후 배양액으로부터 항균활성물질의 규명을 시도하였다. 항진균 물질과 같은 이차대사산물의 생산에 증가시키는 $K_2$$HPO_4$와 칼슘이온이 포함된 GSS배지에서 방선균 SKM338 균주를 180 rpm, $30^{\circ}C$, 5일 동안 배양하여 얻어진 배양 상등액으로부터 물리화학적인 방법으로 항진균 활성이 있는 물질을 분리 정제한 결과 참외의 만고병에 대한 생물농약으로 개발 가능한 방선균 유래의 항진균성 물질은 NMR, IR, UV 및 Mass spectral data 분석 등을 통해 polyene macrolide계에 속하는 항생물질인 Flavofungin, Fungichromin, Filipins로 밝혀졌으며 이들의 응용을 기대해 본다.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1226-1231
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• 2014

The rare actinomycete Pseudonocardia autotrophica was previously shown to produce a solubility-improved toxicity-reduced novel polyene compound named $\underline{N}ystatin$-like $\underline{P}seudonocardia$ $\underline{P}olyene$ (NPP). The low productivity of NPP in P. autotrophica implies that its biosynthetic pathway is tightly regulated. In this study, $wblA_{pau}$ was isolated and identified as a novel negative regulatory gene for NPP production in P. autotrophica, which showed approximately 49% amino acid identity with a global antibiotic down-regulatory gene, wblA, identified from various Streptomycetes species. Although no significant difference in NPP production was observed between P. autotrophica harboring empty vector and the S. coelicolor wblA under its native promoter, approximately 12% less NPP was produced in P. autotrophica expressing the wblA gene under the strong constitutive $ermE^*$ promoter. Furthermore, disruption of the $wblA_{pau}$ gene from P. autotrophica resulted in an approximately 80% increase in NPP productivity. These results strongly suggest that identification and inactivation of the global antibiotic down-regulatory gene wblA ortholog are a critical strategy for improving secondary metabolite overproduction in not only Streptomyces but also non-Streptomyces rare actinomycete species.

• KSBB Journal
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• 제22권4호
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• pp.218-221
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• 2007

본 연구에서는 초음파 파쇄기를 이용하여 폴리엔 항진균 활성을 갖는 방선균 배양액으로부터 pellet을 회수하여 미생물농약으로 사용이 용이한 포자를 확보하기 위한 최적화 연구를 수행하였다. 그 결과, Streptomyces sp. MMBL001, MMBL003 그리고 Pseudonocardia autotrophica는 각각 12%, 18%, 12% 출력 (100%, 700 W)에서 최적의 포자 전환율을 보임을 확인하였다. 이렇게 확보한 포자를 10% skim milk 보호제를 사용하여 동결건조한 후 각각의 생균수를 측정한 결과, MMBL003이 MMBL001과 P. autotrophica에 비해 3배 이상의 생균수가 유지됨이 측정되었다. C. albicans를 대상으로 항진균 효과를 확인한 결과, 동결건조된 3종의 방선균주 모두 우수한 항진균 활성을 유지함으로써 신규 폴리엔 생산 방선균을 이용한 미생물농약으로서의 활용 가능성을 제시하였다.

• 생명과학회지
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• 제14권2호
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• pp.225-228
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• 2004

나타마이신 배양액을 4$^{\circ}C$와 실온에서 14일 동안 보관하였을 때, 4$^{\circ}C$에서는 나타마이신의 활성이 80% 이상 유지되었으나 실온에서는 27%로 급격하게 감소하였다. 이러한 사실은 나타마이신의 손실을 최소화하기 위해서는 최단 시간 내에 배양액으로부터의 나타마이신을 회수할 필요성과 장기간 보관 시에는 4$^{\circ}C$이하에서 보관할 필요성을 제시하고 있다. 효율적인 나타마이신 정제과정을 개발하기 위해 배양액으로부터의 나타마이신의 추출 용매 및 적정 사용량에 대해 조사한 결과 2g의 나타마이신을 추출하는데 1 l의 methanol을 사용하는 것이 가장 효율적이었다. 확립된 나타마이신 추출에 필요한 methanol의 양과 Diaion HP-20을 이용한 column chromatography를 적용하여 4.2 g의 나타마이신이 함유된 1,800 ml의 배양액으로부터 2.9 g의 나타마이신을 획득하였다. 본 연구에서 개발된 정제과정을 통해 순도가 96.6%이고 회수율이 69.1%인 나타마이신을 얻을 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제32권7호
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• pp.911-917
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• 2022

As valuable antibiotics, microbial natural products have been in use for decades in various fields. Among them are polyene compounds including nystatin, amphotericin, and nystatin-like Pseudonocardia polyenes (NPPs). Polyene macrolides are known to possess various biological effects, such as antifungal and antiviral activities. NPP A1, which is produced by Pseudonocardia autotrophica, contains a unique disaccharide moiety in the tetraene macrolide backbone. NPP B1, with a heptane structure and improved antifungal activity, was then developed via genetic manipulation of the NPP A1 biosynthetic gene cluster (BGC). Here, we generated a Streptomyces artificial chromosomal DNA library to isolate a large-sized NPP B1 BGC. The NPP B1 BGC was successfully isolated from P. autotrophica chromosome through the construction and screening of a bacterial artificial chromosome (BAC) library, even though the isolated 140-kb BAC clone (named pNPPB1s) lacked approximately 8 kb of the right-end portion of the NPP B1 BGC. The additional introduction of the pNPPB1s as well as co-expression of the 32-kb portion including the missing 8 kb led to a 7.3-fold increase in the production level of NPP B1 in P. autotrophica. The qRT-PCR confirmed that the transcription level of NPP B1 BGC was significantly increased in the P. autotrophica strain containing two copies of the NPP B1 BGCs. Interestingly, the NPP B1 exhibited a previously unidentified SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) inhibition activity in vitro. These results suggest that the Streptomyces BAC cloning of a large-sized, natural product BGC is a valuable approach for titer improvement and biological activity screening of natural products in actinomycetes.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.121-127
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• 2004

Amphotericin B (AmB), an amphipathic polyene macrolide, is an antifungal drug produced by Streptomyces nodosus. Recently, AmB has been shown to exert antiviral activity against rubella virus and human immunodeficiency virus by different mechanisms. In this study, we evaluated the antiviral effect of AmB against Japanese encephalitis virus (JEV) and investigated which step of the viral life cycle was inhibited by AmB to understand the mechanism of antiviral action of AmB. AmB reduced both plaque size and number in the infected cells in a dose-dependent manner. In addition, a 200-fold reduction of infectious virus titer was observed by treatment of infected cells with $5\mug/ml$ of AmB. AmB acted at the post virus-infection step, but not during adsorption of virus to host cells. Western blot analysis revealed that the accumulated level of JEV envelope protein dramatically decreased in the infected cells by treatment with $5-10\mug/ml$ of AmB. Our results indicate that AmB inhibits the replication of JEV at the postinfection step by interfering with viral replication and/or by inhibiting the synthesis of viral proteins.

• Archives of Pharmacal Research
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• 제28권7호
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• pp.756-760
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• 2005

Polyene macrolide amphotericin B (AmB) is the drug of choice for the treatment of disseminated fungal infections. However, because of its pronounced side effects, the drug has limited applicability. There are few interesting reports, which state that co-administration of the drug with homo-peptide of polyaspartic acid reduces the side effects of the drug. In our present study, an approach has been made to systematically synthesize low molecular weight heteropeptides consisting of L-aspartic acid and its derivative. It was hypothesized that such heteropeptides will reduce the toxic side effects of the drug by facile hydrophobic binding between the polymer and the drug. We have employed the strategy of solid phase peptide synthesis (SPPS) to synthesize low molecular weight hetero-peptides by using L-aspartic acid and benzyl-L-aspartic acid to induce the hydrophobic binding between the peptide and the drug. In future, the proposed methodology can be employed to tailor other polypeptides substituted with benzyl groups to reduce the nephrotoxicity of AmB.