• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 추계학술대회 및 정기총회
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• pp.37-37
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• 2015

dsRNA was found in malformed cultures of Lentinula edodes strain FMRI0339, one of the three most popular sawdust cultivated commercial strains of shiitake, and was also found in healthy-looking fruiting bodies and actively growing mycelia. Cloning of the partial genome of the dsRNA revealed the presence of the RdRp sequence of a novel L. edodes mycovirus (LeV), and sequence comparison of the cloned amplicon showed an identical sequence to known RdRp genes of LeV found in strain HKA. The meiotic stability of dsRNA was examined by measuring the ratio of the presence of dsRNA among sexual monokaryotic progeny. More than 40% of the monokaryotic progeny still contained the dsRNA, indicating the persistence of dsRNA during sexual reproduction. Comparing the mycelia growth of monokaryotic progeny suggested that, although variations in the growth rate existed among progeny and virus infection was observed in highly actively growing progeny, there appeared to be a tendency toward a lower frequency of virus incidence in actively growing progeny. This study attempted to cure the edible mushroom L. edodes strain FMRI0339 of the L. edodes mycovirus (LeV) in order to obtain an isogenic virus-free fungal strain as well as a virus-infected strain for comparison. Mycelial fragmentation, followed by being spread on a plate with serial dilutions resulted in a virus-free colony. Viral absence was confirmed with gel electrophoresis after dsRNA-specific virus purification, Northern blot analysis, and PCR using reverse transcriptase (RT-PCR). Once cured, all of fungal cultures remained virus-free over the next two years. Interestingly, the viral titer of LeV varied depending on the culture condition. The titer from the plate culture showed at least a 20-fold higher concentration than that grown in the liquid culture. However, the reduced virus titer in the liquid culture was recovered by transferring the mycelia to a plate containing the same medium. In addition, oxygen-depleted culture conditions resulted in a significant decrease of viral concentration, but not to the extent seen in the submerged liquid culture. Although no $discernable phenotypic changes in colony morphology were observed, virus-cured strains showed significantly higher growth rates and mycelial mass than virus-infected strains. We were also explored effects of LeV on fruiting body formation and mushroom yield. The fruiting body formation yield of virus-free L. edodes was larger than virus-infected L. edodes. These results indicate that LeV infection has a deleterious effect on mycelial growth and fruiting body formation. In addition, we have been investigated host-parasite interaction between L. edodes and its mycovirus interaction to study viral mechanism by establishment of proteomics.

• 한국균학회지
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• 제46권2호
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• pp.177-185
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• 2018

야생 표고 26개 균주를 육종의 소재로 활용할 목적으로 배양 특성 및 버섯 생산성과 자실체의 특성 등을 조사하였다. potato dextrose agar 배지에서 균사의 배양 온도($10^{\circ}C$, $20^{\circ}C$, $30^{\circ}C$)에 따른 균사 생장력을 측정한 결과, 3가지 온도 조건에서 공통적으로 평균 이상의 생장력을 갖는 균주는 NIFoS 68, NIFoS 136, NIFoS 1521, NIFoS 1651, NIFoS 2064였다. NIFoS 411 균주는 $20^{\circ}C$에서 가장 저조한 생장을 보인 반면 $30^{\circ}C$에서 가장 높은 생장을 보였다. 배양 배지의 중량 감소율은 13.5~47.5%로 NIFoS 50 (47.5%), NIFoS 128 (34.5%), NIFoS 54 (34.4%) 순으로 조사되었다. 또한 26개 균주 중 24개 균주에서 버섯이 발생되었고, 생산성은 3~446 g/2 kg이었다. 버섯 생산량과 온도별 균사 생장력은 크게 상관관계를 보이지 않았으나 중량 감소율이 클수록 자실체 수확량이 높은 상관관계를 보였다. 생산량 측면을 고려할 때, 3개 균주 NIFoS 50 (446 g), NIFoS 53 (421 g), NIFoS 952 (435 g)은 육종 소재로 활용 가능하였고, 형태적인 면을 고려할 때 NIFoS 667 균주가 우수하였으며, NIFoS 670 균주는 자실체의 갓이 황갈색인 특징을 보였다.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.117.3-118
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• 2003

We tested for the presence of double-stranded RNA (dsRNA) mycovirus in 827 Fusarium graminearum isolated from diseased barley and maize. dsRNA mycoviruses with various sizes were isolated. Of them, it was previously reported that dsRNA from DK2l isolate had pronounced morphological changes, including reduction in mycelial growth, increased to red pigmentation, reduced virulence and sporulation. (Chu et al., Appl. Environ. Microbiol. 2002). For better understanding of this hypovirulence associated with DK2l dsRNA virus, we determined the complete nucleotide sequence of dsRNA genome and named Fusarium hypovirus DK2l strain (Fhv-DK2l ). Genomic RNA of Fhv-DK2l was determined to be 6625 nucleotides in length excluding the poly (A) tail and contained three putative open reading frame. RNA-dependent RNA polymerase (RdRp) and helicase domain were expected in ORF A, 54 to 4709 nucleotide position. ORE B, 4752 to 5216 nucleotide position, and ORF C, 5475 to 6578 nucleotide position, were predicted to encode 16.7kDa and 41.3kDa protein respectively each. We could not detect any conserved domains from these two proteins. Phylogenetic analysis showed Fhv-DK2l was related to Cryphonectria hypovirus 3. Ten additional isolates were found that were infected with dsRNA mycoviruses. These mycoviruses contain 2 to 4 different segments of dsRNAs with the size range of approximately 1.7 to 10-kbp in length. The presence of dsRNAs isolates did not affect colony morphology and were transmissible through conidia and ascospore with incidence of 30-100％. These results indicate that there is genomic diversity of dsRNA mycoviruses that infect F. graminearum isolates and that impact of virus infection on host's morphology and virulence is determined by the interaction between dsRNAs and the fungal host, not by the mere presence of the dsRNAs

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.1-7
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• 2002

The effects of DO and pH on the mass production of pullulan with high molecular weight and the morphology of A. pullulans ATCC 42023 were evaluated. A. pullulans showed a maximum production of pullulan (11.98 g/l) when the initial pH of the culture broth was 6.5 in a shake-flask culture. In a batch culture, the mixture of a yeast-like and mycelial cell forms was found at a pH of 4.5, and the maximum production of pullulan (13.31 g/l) was obtained. However, a high proportion of high molecular weight pullulan (M.W.>2,000,000) was produced at a pH of 6.5, with a yeast-like morphology. The maximum pullulan production yield ($51\%$) was obtained at a pH noncontrol (initial pH 6.5) and DO control (above $50\%$) condition. Pullulan degrading enzyme was activated when the pH of the broth was lower than 5.0 and the portion of low molecular weight pullulan was increased. The formation of a black pigment was observed at an initial stationary phase, at 40 h of fermentation. Therefore, the fermentation should be carried out in a pH noncontrol (initial pH of 6.5) and DO control (above $50\%$) condition, and should be harvested before reaching the stationary phase (around 40 h) for the production of high molecular weight pullulan.

• 한국균학회지
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• 제20권3호
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• pp.222-228
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• 1992

사철 느타리버섯 영양요구성(營養要求性) 균주(菌株)를 팽이버섯 leu 2 유전자를 지닌 pM 301 백터를 이용(利用)하여 영양요구성(營養要求性)을 보완(補完) 시킴으로써 형질전환(形質轉換) 하였다. 형질전환균주(形質轉換菌株)의 균사생장(菌絲生長)을 버섯 완전배지(完全培地)나 버섯 최소(最小) 배지(培地)에서 비교(比較)하였다. 형질전환주(形質轉換株)는 1 핵(核) 균사(菌絲)와 교배(交配)후 자실체(子實體) 형태(形態)를 비교(比較)하고 포자 분석(分析)에 의하여 유전분석(分析)을 하였다. 자실체(子實體) 발생(發生)과 자실체(子實體) 모양이 형질전환주(形質轉換株)는 모균주와 다른 특성(特性)이 나타났다. 모균주(母菌株)는 교배형(交配型)이 $A_1B_1$으로 $A_2B_1$ 교배형(交配型)인 1핵(核) 균주(菌株)와 교배(交配)에 의하여 자실체(子實體)를 형성(形成)하지 못하나 형질전환주(形質轉換株)는 교배형(交配型)이 $A_1B_1$이고 $A_2B_1$ 1핵(核) 균주(菌株)와 교배(交配) 하였을때 자실체(子實體)를 형성(形成)하였다.

• Mycobiology
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• 제33권1호
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• pp.7-11
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• 2005

Twenty-two isolates of Sclerotium rolfsii causing spotted leaf rot from Varanasi, India were grown on 6% Cyperus rotundus rhizome meal agar (CRMA) medium for the induction of athelial stage (Athelia rolfsii). Only one isolate obtained from Sphaeranthus indicus formed basidial stage on CRMA medium while the other 21 isolates did not. Basidial stage was also produced in S. indicus isolate at different concentrations (5.5, 6.0 and 6.5% w/v) of CRMA medium. Size of basidia, sterigmata and basidiospores of this isolate was measured. Basidia clavate, hyaline and measured $10{\sim}12{\times}4{\sim}5\;{\mu}m$ in size, basidiospores hyaline, unicellular, subglobose to ellipsoid produced on sterigmata and measured $3{\sim}5{\times}2{\sim}4\;{\mu}m$ in size, sterigmata hyaline and measured $4{\sim}5{\times}1.5{\sim}2\;{\mu}m$ in size. The results of the present study revealed wide variation in spotted leaf rot isolates of S. rolfsii. A reddish zone around the colony of S. rolfsii isolate from Vernonia sp. was observed on CRMA medium. HPLC analysis of the zone revealed the presence of gallic and ferulic acid which were also thought to be responsible for reduced mycelial growth of the isolate on CRMA medium.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1170-1175
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• 2004

The involvement of the relA and rsh genes in the morphological and physiological differentiation of Streptomyces clavuligerus was evaluated with the relA and rsh genes mutants. The morphological differentiation of S. clavuligerus was greatly affected by the disruption of the relA gene, but not very much by the disruption of the rsh gene. The altered morphological characteristics were completely restored by the complementation of the corresponding disrupted genes. Thus, it was apparent that the mycelial morphology and clavulanic acid production were severely affected by the disruption of the relA gene. Production of clavulanic acid in the submerged batch culture and glycerol-limited chemostat showed that production was inversely related to the specific growth rate in the wild-type strain. However, the production of clavulanic acid in the ${\Delta}relA$ and ${\Delta}rsh$ null mutants was completely abolished. Therefore, it seems plausible that the stringent response of S. clavuligerus to starvation for amino acids is governed mainly by ReIA, rather than Rsh, and that the (p)ppGpp synthesized immediately after the depletion of amino acids triggers the initiation of pathways for both morphological and physiological differentiation in this species.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.380-383
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• 2000

불완전 곰팡이의 일종인 Aureobasidium pullulans ATCC 42023 균주를 이용한 pullulan의 최적조건 및 pH 조절에 따른 pullulan의 생성 그리고 균체형태와 고분자 pullulan 생산에 미치는 영향을 조사 하였다. 삼각플라스크 내에서 최대의 pullulan 생산은 초기 pH 6.5일때 11.98 g/l의 pullulan을 생산하였고, 회분식 발효에서는 산소 공급속도 0.5 vvm일때 15.16 g/l의 최대의 pullulan생산량을 나타내었다. pH조절에 따른 실험에서는 pH 4.5일때 13.31 g/l의 pullulan 생산량을 보였고, 이때 균체의 형태는 효모형과 균사형태의 성장을 하였다. 그러나 분자량 생성면에서는 pH 6.5일때 100만 이상의 고분자가 가장 많이 생산되었다.

• 한국식물병리학회지
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• 제14권3호
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• pp.268-277
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• 1998

The production of Korean ginseng, one of the most important medicinal root crops, is limited by many factors including soil sickness, root rots in fields as well as during storage prior to consumption. Although much research has been conducted on the diseases in field condition, little information is available on the control of postharvest roots rots. To obtain better management strategy of postharvest root rots in ginseng, biological control using antagonistic bacteria was attempted. Of 208 bacteria obtained form suppressive soil samples, 4 were selected based on the inhibitory effect on mycelial growth of two major causal fungi for postharvest root rots in ginseng, Botrytis cinerea and Fusarium solani. The culture filtrates of these bacterial antagonists greatly inhibited the conidial germination of both pathogenic fungi and produced abnormal morphology such as swollen germ tubes in F. solani and vacuolation of nongerminated conidia in B. cinerea. The population levels of bacterial antagonists on the ginseng roots were gradually increased up to 8 days of incubation. Postharvest root rots of ginseng caused by f. solani and B. cinerea were controlled in dipping tests in the ranges of 60∼80% by antagonistic Bacillus spp. obtained from suppressive soil. These results suggest that biological control using these antagonistic bacteria would be an alternative strategy to control postharvest root rots in ginseng.

• 식물병연구
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• 제26권2호
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• pp.109-115
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• 2020

A disease causing leaf blight and vine rot was recognized on kudzu plants (Pueraria lobata) in Korea since 1991. A species of Phytophthora has been repeatedly isolated from the infected leaves. Identification in species level of the Phytophthora sp. remained unsolved. An isolate, KACC 47616 originally collected from Manchon Park in Daegu, has been kept in our laboratory. In 2013, three new isolates, KACC 47617 and KACC 47618 from Yeongyang and KACC 47619 from Gunwi in Gyeongbuk province, were collected and examined to classify up to species level by characterizing morphology, response to temperature and phylogenetic relationship. On the basis of morphological characters such as the nature of hyphal swelling, sporangia and sex organs, absence of chlamydospore production, optimum temperature for mycelial growth, and internal transcribed spacer rDNA and cytochrome oxidase subunit 1 sequence analysis of the pathogen, the causal fungus of kudzu plant was identified as Phytophthora asiatica.