• 한국미생물·생명공학회지
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• 제40권4호
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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.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.71-76
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• 2002

Soil samples were screened for actinomycete strains capable of producing phospholipase D, and a strain, Streptomyces sp. YU100, showing a high transphosphatidylation activity was isolated. This strain secreted phospholipase D in a culture broth after 12 h of cultivation, and its productivity continued to increase for 36 h of fermentation. In addition, its transphosphatidylation rate of phosphatidylcholine to phosphatidylserine was almost $68\%$ within 1 h. The morphological and chemotaxonomical characteristics showed that this strain could be classified as a number of the Streptomycetaceae family, particularly due to the spiral form of its spore chain consisting of 60-70 smooth spores $(0.75{\times}1.0{\mu}m$) on an aerial mycelium, FA-2c type of fatty acid profile in the cell wall, and LL-DAP component in the cell wall peptidoglycan. A phylogenetic analysis of the 16S rDNA provided a clue that the strain YU100 was actually a member of the genus Streptomyces, because the determined sequence exhibited a higher homology with Streptomyes sp. ASB27, S. peucetius JCM9920, and S. griseus ATCC10137. A dendrogram based on the 16S rDNA sequences also showed a phylogenetic relationship between the strain YU100 and these strains. However, the strain YU100 has not yet been assigned to a particular species, because of absence of any other classified species with a high matching score.

• 미생물학회지
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• 제32권1호
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• pp.70-77
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• 1994

Streptomyces coelicolor를 화학적 방법으로 돌연변이시킨 결과, 유전적 교잡방법에 의해 bldA와 유사한 위치인 10시 방향으로 위치가 결정되는 변이주들을 찾아내었다. 이들의 자세한 위치를 점검한 결과 cysA를 중심으로 반시계 방향으로 떨어져 있는 group고가 시계방향으로 떨어져 있는 두가지로 나뉘었다. 반시계 방향으로 떨어져 있는 변이주들을 bldA와 유사한 변이주라고 생각되어 이를 확인하기 위해 정상적인 bldA 유전자가 cloning 되어 있는 phage를 이용하여 기능적인 complementation 여부를 확인하여 보았다. Complementation이 되는 것으로 미루어 보아 이 변이주들이 bldA의 allele일 가능성이 매우 높으나 이들 중 몇몇 변이주들은 기존의 bldA와 무척 다른 양상을 보였다. 즉, 고영양 배지인 $R_2$YE배지에서 왕성하게 spore를 생산하며 wild type이 생산하는 이상의 색소 생산을 보인 점이다. 이때까지 발견된 bldA 변이주들은 배지 조성에 따라 약간의 aerial mucelium을 형성하는 것이 보고되었으나 이렇게 조건에 따라서는 완전히 bld phenotype을 잃는 변이주는 보고되지 않았다. 이 색소 생산이 실지로 항생물질 유전자의 발현에 의한 것이라는 것을 xylE fusion을 이용했을 때 유전자의 전사가 일어나는 것이 확인됨으로써 증명되었다. 또 이들 bldA 유사 변이주들은 actII-ORF4가 높음 copy수로 들어있는 pasmid에 의해 act 유전자를 발현하는 것도 관찰되었다.

• The Plant Pathology Journal
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• 제29권1호
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• pp.52-58
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• 2013

Fusarium head blight (FHB) caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed.

• 미생물학회지
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• 제47권4호
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• pp.375-380
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• 2011

천안의 단국대학교 근처에서 채취된 벼 뿌리로부터 내생 방선균 한 주를 분리 동정하였다. 표면 살균된 벼 뿌리를 분리 배지 위에 올려 놓고 배양하면 4주 후에 뿌리 표면에 형성된 방선균 콜로니를 볼 수 있었다. 이 중에서 한 균주 JK-5를 분리하여 동정하였다. 16S rDNA 염기서열을 확인한 결과 이 분리균주 JK-5는 Streptomyces diastaticus subsp. ardesiacus와 동일한 균주였다. 형태학적 관찰과 화학분류학적 결과에 의해 분리균주 JK-5의 분류학적 위치를 확인하였다. 기중균사의 형태는 flexible하며 포자사슬은 타원형의 약 30개 정도의 매끄러운 포자로 이루어 졌다. 세포벽은 L,L-diaminopimelic acid를 포함하고 있었다. 당 분석에서는 특이적인 당이 발견되지 않았다. 지방산으로는 anteiso-15:0, anteiso-17:0, iso-16:0 가 주요 성분이었다. 퀴논 분석결과 MK-9 ($H_6$)와 MK-9 ($H_8$)이 주요 성분으로 나타났다. GC 함량은 72%로 측정되었다. 식물병원성 곰팡이에 대하여 비교적 높은 항진균활성을 보여 주었다. 벼에 감염된 분리균주 JK-5가 뿌리와 줄기에서 균사체를 형성하며 왕성하게 생장하는 것을 SEM을 통하여 확인하였다.