• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.429-438
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• 2017

For centuries, plants have been used for a wide variety of purposes, from treating infectious diseases to food preservation and perfume production. Presently, the increasing resistance of microorganisms to currently used antimicrobials in combination with the appearance of emerging diseases requires the urgent development of new, more effective drugs. Plants, due to the large biological and structural diversity of their components, constitute a unique and renewable source for the discovery of new antibacterial, antifungal, and antiparasitic compounds. In the present paper, the history, composition, and antimicrobial activities of the basil, oregano, and thyme essential oils are reviewed.

• BMB Reports
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• 제36권6호
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• pp.603-607
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• 2003

Abstract Plant lipid transfer proteins (LTPs) are a class of proteins whose functions are still unknown. Some are proposed to have antimicrobial activities. To understand whether LTP110, a rice LTP that we previously identified from rice leaves, plays a role in the protection function against some serious rice pathogens, we investigated the antifungal and antibacterial properties of LTP110. A cDNA sequence, encoding the mature peptide of LTP110, was cloned into the Impact-CN prokaryotic expression system. The purified protein was used for an in vitro inhibition test against rice pathogens, Pyricularia oryzae and Xanthomonas oryzae. The results showed that LTP110 inhibited the germination of Pyricularia oryzae spores, and its inhibitory activity decreased in the presence of a divalent cation. This suggests that the antifungal activity is affected by ions in the media; LTP110 only slightly inhibited the growth of Xanthomonas oryzae. However, the addition of LTP110 to cultured Chinese hamster ovarian cells did not retard growth, suggesting that the toxicity of LTP110 is only restricted to some cell types. Its antimicrobial activity is potentially due to interactions between LTP and microbe-specific structures.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 추계학술대회 및 정기총회
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• pp.28-28
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• 2015

Asexual reproduction or conidiation in aspergilli is a primary mean to produce their progenies that is environmentally and genetically controlled tightly. Previously, intensive researches in the model fungus Aspergillus nidulans disclosed some genes playing important roles in asexual and sexual development. Among them, one gene encoding a putative helix-loop-helix (HLH) transcription factor, named ndrA, has been isolated and characterized as a downstream regulator of developmental master regulator NsdD. By using comparative genome search of A. niduans NdrA protein, its orthologues have been identified in A. fumigatus and A. flavus, respectively (AfudrnA and AfldrnA). Deletion of the ndrA genes in both Aspergillus species made them unable to produce the conidia yet abundant production of sclerotia in A. flavus. Complementation of ndrA deletion strains by intact ndrA ORFs has restored the conidiation as in the control strains. In A. fumigatus, ndrA deletion also resulted in loss of conidiation phenotype. Northern analyses showed that the ndrA genes in both Aspergillus species are highly expressed at the early stage of the conidiation. Interestingly, the ndrA genes were found to be necessary for the proper expression of brlA genes. Antifungal sensitivity test revealed that the ndrA genes might be responsible for the sensitivity or resistance to some antifungal agents. However, ndrA deletion did not greatly influence the growth in both strains. And the A. flavus ndrA gene did not affect the aflatoxin production. Taken together, ndrA genes in Aspergillus species could be an important positive regulator of conidiation under the regulation of the nsdD gene yet upstream of the brlA gene.

• Journal of Dairy Science and Biotechnology
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• 제40권3호
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• pp.103-109
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• 2022

항균활성을 가진 유산균은 생균제 등의 형태로 식품 중 부패나 식중독을 유발하는 유해균을 저해하는데 효과적으로 활용할 수 있다. 이에 본 연구에서는 된장에서 분리한 유산균인 P. pentosaceus M132-2 균주를 주요 오염 곰팡이 3종을 대상으로 분석한 결과, 이들의 생장을 모두 저해하여 항곰팡이능을 보유한 것을 확인하였다. 또한 M132-2 균주는 우수한 내염성과 저온내성을 가지고 있어 치즈의 염도와 저온의 숙성온도에서도 생존이 가능할 것으로 판단된다. 마지막으로 M132-2 상등액을 실제 고다 치즈에 적용한 결과, 오염 곰팡이 생장이 현저하게 저해되는 것을 확인하였다. 결과적으로 P. pentosaceus M132-2 균주는 치즈를 비롯한 다양한 식품의 부패 방지에 활용할 수 있는 유용한 수단이 될 수 있다.

• Mycobiology
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• 제30권1호
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• pp.31-36
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• 2002

Soil bacteria were screened for the ability to control cucumber anthracnose caused by Colletotrichum orbiculare through induced systemic resistance(ISR). Sixty-four bacterial strains having in vitro antifungal activity were used for selecting ISR-inducing strains in cucumber. Cucumber seeds(cv. Baeknokdadagi) were sown in potting mixtures incorporated with the soil bacteria, at a rate of ca. $10^8$ cells per gram of the mixture. Two week-old plants were then transplanted into the steam-sterilized soil. Three leaf-stage plants were inoculated with a conidial suspension($5{\times}10^5$ conidia/ml) of C. orbiculare. Diseased leaf area(%) and number of lesions per $cm^2$ leaf were evaluated on third leaves of the plants, $5{\sim}6$ days after inoculation. Among 64 strains tested, nine strains, GC-B19, GC-B35, GK-B18, MM-B22, PK-B14, RC-B41, RC-B64, RC-B65, and RC-B77 significantly(P=0.05) reduced anthracnose disease compared to the untreated control. In contrast, some bacterial strains promoted susceptibility of cucumber to the disease. From the repeated experiments using the nine bacterial strains, GC-B19, MM-B22, PK-B14, and RC-B65 significantly(P=0.05) reduced both diseased leaf area(%) and number of lesions per $cm^2$ leaf in at lease one experiment. These strains with control efficacy of $37{\sim}80%$ were determined to be effective ISR-inducing strains.

• 한국토양비료학회지
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• 제35권4호
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• pp.223-231
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• 2002

인산가용 미생물인 Enterobacter intermedium 60-2G의 식물생장촉진 능력과 흑성병균인 Cladosporium cucumerinum에 대한 유도전신저항성 능력을 오이와 오이 흑성병균을 모델로 확인하였다. E. intermedium 을 처리한 오이는 물을 처리한 control에 비해 C. cucumerinum에 의한 흑성병의 병징이 현저히 감소하였다. 또한 E. intermedium를 처리한 오이는 식물 생장촉진효과도 보였다. Strain 60-2G은 Fusarium oxysporum와 Magnaporthe grisea을 포함한 여러 식물 병원 곰팡이에 대해 강한 항균활성을 나타내었다. 본 연구는 인산가용능력을 가진 E. intermedium 60-2G는 식물의 생육을 증진시키는데 관여하는 여러가지 유익한 형질을 가진 아주 유용한 생물적 방제균임을 밝혔다.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1149-1161
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• 2014

Cotton plants were sampled and ranked according to their resistance to Verticillium wilt. In total, 642 endophytic fungi isolates representing 27 genera were recovered from Gossypium hirsutum root, stem, and leaf tissues, but were not uniformly distributed. More endophytic fungi appeared in the leaf (391) compared with the root (140) and stem (111) sections. However, no significant difference in the abundance of isolated endophytes was found among resistant cotton varieties. Alternaria exhibited the highest colonization frequency (7.9%), followed by Acremonium (6.6%) and Penicillium (4.8%). Unlike tolerant varieties, resistant and susceptible ones had similar endophytic fungal population compositions. In three Verticillium-wilt-resistant cotton varieties, fungal endophytes from the genus Alternaria were most frequently isolated, followed by Gibberella and Penicillium. The maximum concentration of dominant endophytic fungi was observed in leaf tissues (0.1797). The evenness of stem tissue endophytic communities (0.702) was comparatively more uniform than the other two tissues. Eighty endophytic fungi selected from 27 genera were evaluated for their inhibition activity against highly virulent Verticillium dahliae isolate Vd080 in vitro. Thirty-nine isolates exhibited fungistasis against the pathogen at varying degrees. Seven species, having high growth inhibition rates (${\geq}75%$), exhibited strong antifungal activity against V. dahliae. The antifungal activity of both volatile and nonvolatile metabolites was also investigated. The nonvolatile substances produced by CEF-818 (Penicillium simplicissimum), CEF-325 (Fusarium solani), CEF-714 (Leptosphaeria sp.), and CEF-642 (Talaromyces flavus) completely inhibited V. dahliae growth. These findings deepen our understanding of cotton-endophyte interactions and provide a platform for screening G. hirsutum endophytes with biocontrol potential.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.134-134
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• 2017

Recently, host-induced gene silencing (HIGS) system has been successfully applied into development of resistant crops against insects, fungal and viral pathogens. To test HIGS-mediated resistance in rice against rice blast fungus, Magnaporthe oryzae, we first tested possibility of movement of small non-coding RNA from rice cells to rice blast fungus. The rice blast fungus expressing GFP transgene were inoculated to transgenic rice plants ectopically expressing dsRNAi construct targeting fungal GFP gene. Expression of dsRNAi construct for GFP gene in transgenic plants significantly suppressed GFP expression in infected fungal cells indicating that small RNAs generated in plant cells can move into infected fungal cells and efficiently suppress the expression of fungal GFP gene. Consistent with these results, expression of dsRNAi constructs against 3 fungal pathogenic genes of M. oryzae in transgenic rice specifically and efficiently suppressed not only the expression of fungal pathogenic genes, but also fungal infection. The conidia of M. oryzae applied on leaf sheath of transgenic rice expressing dsRNAs against 3 fungal pathogenic genes showed abnormal development of primary hyphae and malfunction of appressorium, which is consistent with the phenotypes of corresponding fungal knock-out mutants. Taken these results together, here, we suggest a novel strategy for development of antifungal crops by means of HIGS system.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.685-693
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• 2017

Candidiasis involving the biofilms of Candida albicans is a threat to immunocompromised patients. Candida biofilms are intrinsically resistant to the antifungal drugs and hence novel treatment strategies are desired. The study intended to evaluate the anti-Candida activity of allyl isothiocyanate (AITC) alone and with fluconazole (FLC), particularly against the biofilms. Results revealed the concentration-dependent activity of AITC against the planktonic growth and virulence factors of C. albicans. Significant (p <0.05) inhibition of the biofilms was evident at ${\leq}1mg/ml$ concentrations of AITC. Notably, a combination of 0.004 mg/ml of FLC and 0.125 mg/ml of AITC prevented the biofilm formation. Similarly, the preformed biofilms were significantly (p <0.05) inhibited by the AITC-FLC combination. The fractional inhibitory concentration indices ranging from 0.132 to 0.312 indicated the synergistic activity of AITC and FLC against the biofilm formation and the preformed biofilms. No hemolytic activity at the biofilm inhibitory concentrations of AITC and the AITC-FLC combination suggested the absence of cytotoxic effects. The recognizable synergy between AITC and FLC offers a potential therapeutic strategy against biofilm-associated Candida infections.

• Mycobiology
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• 제46권2호
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• pp.114-121
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• 2018

Mon1 is a guanine nucleotide exchange factor subunit that activates the Ypt7 Rab GTPase and is essential for vacuole trafficking and autophagy in eukaryotic organisms. Here, we identified and characterized the function of Mon1, an ortholog of Saccharomyces cerevisiae Mon1, in a human fungal pathogen, Cryptococcus neoformans. Mutation in mon1 resulted in hypersensitivity to thermal stress. The mon1 deletion mutant exhibited increased sensitivity to cell wall and endoplasmic reticulum stress. However, the mon1 deletion mutant showed more resistance to the antifungal agent fluconazole. In vivo studies demonstrated that compared to the wild-type strain, the mon1 deletion mutant attenuated virulence in the Galleria mellonella insect model. Moreover, the mon1 deletion mutant was avirulent in the murine inhalation model. These results demonstrate that Mon1 plays a crucial role in stress survival and pathogenicity in C. neoformans.