• Journal of Microbiology and Biotechnology
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• 제21권1호
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• pp.14-19
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• 2011

A cyclic undecapeptide-family natural product, cyclosporin A (CyA), which is one of the most valuable immunosuppressive drugs, is produced nonribosomally by a multifunctional cyclosporin synthetase enzyme complex in a filamentous fungal strain named Tolypocladium niveum. Previously, structural modifications of cyclosporins such as a regionspecific hydroxylation at the $4^{th}$ N-methyl leucine in a rare actinomycetes called Sebekia benihana were reported to lead to dramatic changes in their bioactive spectra. However, the reason behind this change could not be determined since a system to genetically manipulate S. benihana has not yet been developed. To address this limitation, in this study, we utilized the most commonly practiced gene manipulation techniques including conjugation-based foreign gene transfer-and-expression as well as targeted gene disruption to genetically manipulate S. benihana. Using these optimized genetic manipulation systems, a putative cytochrome P450 hydroxylase (CYP) gene named CYP506, which is involved in CyA hydroxylation in S. benihana, was specifically disrupted and genetically complemented. The S. benihana${\Delta}$CYP506 exhibited a significantly reduced CyA hydroxylation yield as well as considerable yield restoration by functional complementation of the S. benihana CYP506 gene, suggesting that the genetically manipulated S. benihana CYP mutant strains may serve as a more efficient bioconversion host for various valuable metabolites including CyA.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제20권2호
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• pp.152-157
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• 1998

Disturbances of the interrelationship among the host, environment, microorganism will cause the infection clinically. Infection can be classified into bacterial, viral, fungal origin, Bacterial infection is most common due to dental caries, periodontal disease. These infections have the potential to spread via the fascial spaces in the head and neck region. We have undertaken clinical studies on infections in the oral and maxillofacial regions by analyzing 78 hospitalized patients in the Dept. of Oral and Maxillofacial Surgery, Dong-A University Hospital from 1994 to 1997. The results were as fellows; l. Odontogenic infections were most common with the incidence of 84.6%. 2. Considering the number of involved space, single space was 83.3%, double or more space was 16.6%. The most common fascial space involved was submandibular space and followed by buccal space, 3. The most causative organism isolated from the pus cultures was streptococci group 35.4%. 4. Antibiotics were administrated in all cases, and surgical incision and drainage was performed in 87.2%. 5. Combined administration of penicillin and aminoglycoside was most common in 34.6%.. 6. 7 cases were diagnosed as Ludwig's angina and tracheostomy was done in 2 cases of them.

• The Plant Pathology Journal
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• 제16권4호
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• pp.227-230
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• 2000

A total of 90 isolates of Fusarium oxysporum f.sp. melonis, the causal agent of oriental melon (Cucumis melo var. makuwa) wilt, was isolated from symptomatic tissues of oriental melon from 4 provinces in Korea. These isolates were grouped into vegetative compatibility groups (VCGs) by demonstrating heterokaryosis through complementation using nitrate nonutilizing (nit) mutants. No self-incompatibility was observed in any of isolates. All isolates were grouped into 3 VCGs ; A, B, and C. iSOLATES BELONGING TO VCG A and VCG B accounted for 87% and 91% of the fungal population collected in 1991 and 1993, respectively. As the increment of cultivation period in the same field, the proportion of isolates belonging to VCG B increased whereas that of isolates belonging to VCG A decreased. Mean virulence of a total population increased as the increment of cultivation period in the same field. Isolates belonging to VCG B showed the highest increment of virulence. These data suggest that replanting of a host plant in the same field may cause increase of virulence in the pathogens. Furthermore, virulence of F. oxysporum f.sp. melonis isolates is related to the VCGs.

• The Plant Pathology Journal
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• 제25권1호
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• pp.6-12
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• 2009

Snow molds are the most important winter diseases of turfgrass in the United States and Canada. Eight isolates of three snow mold fungal species (three isolates of Typhula ishikariensis, three of T. incarnata, and two of Microdochium nivale) were collected from infected turfgrasses on golf courses. The isolates were evaluated for their relative aggressiveness on three cultivars (L-93, Penncross, and Providence) of creeping bentgrass (Agrostis palustris) under the same controlled conditions. Four plant ages (15, 19, 23 and 27 week-old plants from germination to inoculation) were evaluated for their susceptibility to the three pathogens and for the recovery of the plants. Regardless of age or cultivar of the host plant, M. nivale was found to be more aggressive and faster to infect and colonize than Typhula species. After three weeks recovery, M. nivale-inoculated plants showed higher disease severity than plants inoculated with the two Typhula species. Plants infected by Typhula species displayed no significant difference in disease severity. As creeping bentgrass plants get older, the severity of disease caused by three snow molds gradually decreases. This effect was observed in all cultivars tested, suggesting expression of age-related resistance as the bentgrass plants matured.

• 한국식품영양과학회지
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• 제14권3호
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• pp.305-313
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• 1985

There is a trend that the total number of cancer cases is steadily increasing as the population grows. It has been estimated that 85% of the cancer rate in the U.S. is attributed to environmental factors. Among the environmental factors, diet and nutrition appear to be related to the largest number of human cancers. Diet and nutrition might be related to cancer by several mechanisms. Food may contain a direct carcinogen or precursors that become carcinogens by spontanous reactions, or by host metabolism, or through the actions of microbial flora. Chemicals that cause cancers generally have reactive electrophilic centers which can combine with electron-rich atoms in nucleic acids and cause cancers by changing the genetic activity of the cells. A variety of factors in foods might be involved in the etiology of carcinogenesis. Chemicals in food that cause cancers include carcinogens of plants and animal origin and also those in drinking water. Other then these, fungal metabolites alcohol, asbestos, heavy metals, pesticides, and food additives might be included as food carcinogenesis. The method of cooking foods also might contribute to carcinogenesis. Some chemicals in foods act as promoters in carcinogenesis. Prevention of cancers by dietary practises have received much interest. Consumption of certain vegetables or cellulose can reduce carcinogenic activity of several compounds. A variety of antioxidants or micronutrients may be effective anticarciongens. Glutathione in the soluble fraction of the cells, is a major defense against oxidative and alkylating carcinogens. Recently anticarcinogenic activity of chlorophyll was demonstrated. Daily consumption of milk appears to effectively reduce stomach cancer.

• 한국식품위생안전성학회지
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• 제7권2호
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• pp.107.2-119
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• 1992

Fish pathology is one of the main scientific bases upon which this expansion in aquaculture has been dependent and requires a wide knowledge of the environmental constraints, the physiology and characteristic of the various pathogens, the responses of the host, and the methods by which they may be controlled. The primary disease and parasite problems in aquaculture animals related to viral, bacteria, fungal and protozoan epizootics. Parasitic nematodes, trematodes and cestodes are commonly found in aquaculture animals, but seldom are they present in concentrations sufficient to cause significant problems, When an epizootic does occur and chemical treatment is indicated, the appropriate chemical must be selected an properly applied. We have antibiotics, sulfa, nitrofuran and other chemicals for treatment of fish diseases, Some may be mixed with the feed during formulation, added to the pellets of feed as a surface coating, given in the form of an injection or used as a bath. Even though a drug or chemical has been officially approved for use in aquaculture, the substance should never be used unless there is a clear need, Some of the reasions for this view are as follows: (1) the constant use of antibiotics can leak to the development of resistant strains of bacteria, (2) biofilter efficiency may be impaired or destroyed by chemicals added to closed recirculating water systems, and(3) the injudicious use of chemical can have a damaging effect on the environment as well as on human.

• Journal of Microbiology and Biotechnology
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• 제16권7호
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• pp.1158-1162
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• 2006

The glyoxylate cycle can conserve carbons and adequately supply tricarboxylic acid (TCA) cycle intermediates for biosynthesis when microorganisms grow on $C_{2}$ carbon sources. It has been reported that isocitrate lyase (ICL1), a key enzyme of the glyoxylate cycle, is highly induced when Magnaporthe grisea, the causal agent of rice blast, infects its host. Therefore, the glyoxylate cycle is considered as a new target for antifungal agents. A 1.6-kb DNA fragment encoding the ICL1 from M. grisea KJ201 was amplified by PCR, cloned into a vector providing His-tag at the N-terminus, expressed in Escherichia coli, and purified using Ni-NTA affinity chromatography. The molecular mass of the purified ICL1 was approximately 60 kDa, as determined by SDS-PAGE. The ICL1 inhibitory effects of TCA cycle intermediates and their analogs were investigated. Among them, 3-nitropropionate was found to be the strongest inhibitor with an $IC_{50}$ value of $11.0{\mu}g/ml$. 3-Nitropropionate inhibited the appressorium development in M. grisea at the ${\mu}M$ level, whereas conidia germination remained unaffected. This compound also inhibited the mycelial growth of the fungus on minimal medium containing acetate as a $C_{2}$ carbon source. These results suggest that ICL1 plays a crucial role in appressorium formation of M. grisea and is a new target for the control of phytopathogenic fungal infection.

• Journal of Microbiology and Biotechnology
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• 제17권11호
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• pp.1797-1804
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• 2007

Lycopene, an acyclic carotenoid found in tomatoes (Lycopersicon esculentum) and a number off fruits, has shown various biological properties, but its antifungal effects remain poorly understood. The current study investigated the antifungal activity of lycopene and its mode of action. Lycopene showed potent antifungal effects toward pathogenic fungi, tested in an energy-independent manner, with low hemolytic effects against human erythrocytes. To confirm the antifungal effects of lycopene, its effects on the dimorphism of Candida albicans induced by fetal bovine serum (FBS), which plays a key role in the pathogenesis of a host invasion, were investigated. The results showed that lycopene exerted potent antifungal activity on the serum-induced mycelia of C. albicans. To understand the antifungal mode of action of lycopene, the action of lycopene against fungal cell membranes was examined by FACScan analysis and glucose and trehalose-release test. The results indicated that lycopene caused significant membrane damage and inhibited the normal budding process, resulting from the destruction of membrane integrity. The present study indicates that lycopene has considerable antifungal activity, deserving further investigation for clinical applications.

• The Plant Pathology Journal
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• 제34권5호
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• pp.367-380
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• 2018

Stems and pods of hyacinth bean cultivated in a farmer's field in Gazipur District, Bangladesh, were found rotted in nearly 5% hyacinth bean plants. A fungus having fluffy mycelium and large sclerotia was isolated from affected tissues. Combined results of morphological, molecular and pathological analyses identified the fungus as Sclerotinia sclerotiorum (Lib) de Bary. Inoculating the fungus on healthy hyacinth bean plants and pods reproduced the symptoms previously observed in the field. The three isolates obtained from naturally infected plants were cross inoculated in hyacinth bean, okra and African-American marigold and they were pathogenic to these hosts. The optimum temperature and pH for its growth were $20^{\circ}C$ and pH 5.0, respectively. Sclerotial development was favored at pH 5.0. Sucrose and mannitol were the best carbon sources to support hyphal growth, while glucose was the most favourable for sclerotial development. The hyacinth bean genotypes, HB-82 (Rupban Sheem) and HB-102 were found highly resistant, while HB-94 (Ashina) was moderate resistant to the fungus. Finally, S. sclerotiorum was sensitive to Bavistin, Dithane M-45 and Rovral fungicides and Ca in the form of $CaCl_2$. This observation could possibly aid in eliminating field loss in hyacinth bean caused by an emerging pathogenic fungus S. sclerotiorum.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.202-202
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• 2017

Global climate change resulted in unwarranted change in global temperature and caused heat and cold stress, which are consider major threat to agriculture productivity around the world. The use of plant growth-promoting microbes is an eco-friendly strategy to counteract such stresses and confer tolerance to the plants. In current study, previously isolated endophytic fungi Preussia sp. BSL-10 has been found to produce phytohormones such as IAA and GA and as such, endophyte Preussia sp. BSL-10 found to induced tolerance against heat and cold stress. The results showed that under both heat and cold stress the plant growth parameter such as shoot, root length, shoot fresh weight and root fresh weight is higher in Preussia sp. BSL-10 treated plants as compare to free Preussia sp. BSL-10 control plants. In addition, the stress-sensitive endogenous ABA levels were significantly increased in Preussia sp. BSL-10 host plant. The current result suggest that the phytohormone-producing endophyte Preussia sp. BSL-10 can increase plant resistance toheat and cold stress, in turn improving agricultural productivity.