• 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.

• 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.

• 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.