• Research in Plant Disease
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• v.29 no.3
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• pp.251-257
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• 2023

In order to examine the pathogenicity of Alternaria dauci, the causal agent of carrot leaf blight, it is necessary to standardize sporulation conditions to ensure the optimal quantity and quality of spore inoculum. Therefore, in this study, the effects of the growth medium, aeration treatment, and UV treatment with 12-hr photoperiod on the sporulation of A. dauci KACC42997 were investigated. A. dauci KACC42997 was pre-cultured for 7 days in a potato dextrose agar medium at 25℃ in the dark condition. When the pre-culture, after removing aerial mycelia, was re-incubated for 5 days, with simultaneous aeration treatment and 12-hr cycle UV treatment at 20℃, the largest number of spores was produced. One hundred seventy isolates of A. dauci were isolated from major carrot growing regions such as Pyeongchang, Gumi and Jeju and tested for sporulation under the conditions established in this study. Except for 20 strains, all strains produced spores. Statistically significant differences in the extent of sporulation were found among local populations of A. dauci isolates, but no difference was observed in their pathogenicity on carrots.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.2
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• pp.137-140
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• 1982

Three levels of inoculum concentration from 10 to 30 percent, three kinds of adhesive materials, gum arabic, methyl cellulose and carboxy methyl cellulose, and five different pelleting materials including 4 different sources of lime and calcium carbonate were compared to investigate an optimum condition for seed inoculation by counting the number of viable rhizobium cells. For a peat-cultured Rhizobium inoculant, 10 per cent was found to be an optimum by showing 3.5 $\times$ 10$^9$ viable cells per seed. The highest number of viable cells were observed from gum arabic at 40 per cent, methyl cellulose at 5 per cent and carboxy methyl cellulose at 4 per cent. Among pelleting materials, a dental lime for investment originated from Ransom & Randolph Co. Ohio, U.S.A. resulted best as pelleting material.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.669-679
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• 2021

This study was conducted to evaluate the effects of rumen-protected amino acid (RPAA) prototypes, which were chemically synthesized, on in vitro rumen fermentation and protection rate outcomes. Several RPAA prototypes were incubated with timothy hay and concentrate. Treatments consisted of 1) control (CON; no RPAA prototype supplement), and prototypes of 2) 0.5% RP-methionine (RPMet), 3) 0.5% RP-tryptophan (RPTrp), 4) 0.5% RP-valine (RPVal), 5) 0.5% RP-phenylalanine (RPPhe), 6) 0.5% RP-leucine (RPLeu), 7) 0.5% RP-histidine (RPHis), 8) 20% RPMet, and 9) 20% RPTrp (w·w^-1 feed). The inoculum (50 mL) prepared with rumen fluid and McDougall's buffer (1 : 4) was dispensed in individual serum bottles and was anaerobically incubated for 0, 6, and 24 h at 39℃ in triplicate. The dry matter degradability did not differ among the groups, except for the 20% RPMet and the 20% RPTrp treatments at 6 and 24 h. The total volatile fatty acid concentration in the 20% RPMet was higher (p < 0.05) than the rest of the groups at 6 h, and 20% RPMet showed the highest molar proportion of acetate, whereas the lowest proportion of propionate was found at 6 h (p < 0.05). The protection rate of the RPAA prototypes ranged from 29.85 to 109.21%. at 24 h. In conclusion, the chemically synthesized RPAA prototypes studied here had no detrimental effects on rumen fermentation parameters. Further studies using animal models are needed for more accurate evaluations of the effectiveness of RPAA.

• Journal of the Korean Society of Food Culture
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• v.21 no.2
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• pp.179-186
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• 2006

To investigate the production of yogurt added with desalted bamboo shoots, the component analysis was conducted. Desalted bamboo shoots contained 82.59 % of moisture, 4.56 % of protein, 0.52 % of lipid, 0.50 % of ash and 11.72 % of total dietary fiber. The main mineral elements were Ca, P, S, Na, Mg and K. Yogurt base fermented with 0.005 % ABT-5 starter inoculum at $40\;^{\circ}C$ for 13 hr. For the preparation of bamboo shoots yogurt, various sugaring bamboo shoots were added to the yogurt base. Results of sensory evaluation of the yogurt containing bamboo shoots indicated that color, odor, taste, flesh size, flesh amount, mouth feel, and overall acceptability of the 15 %(w/v) bamboo shoots dicing $(5{\times}5{\times}5\;mm)$ showed higher preference than others. When bamboo shoot yogurt was kept at $4\;^{\circ}C$ for 15 days, pH, titratable acidity, viable counts of lactic acid bacteria and Bifidobacterium bifidum of yogurt were not changed.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1337-1350
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• 2023

Caproic acid is a precursor substance for the synthesis of ethyl caproate, the main flavor substance of nongxiangxing baijiu liquor. In this study, Clostridium butyricum GD1-1, a strain with high caproic acid concentration (3.86 g/l), was isolated from the storage pit mud of nongxiangxing baijiu for sequencing and analysis. The strain's genome was 3,840,048 bp in length with 4,050 open reading frames. In addition, virulence factor annotation analysis showed C. butyricum GD1-1 to be safe at the genetic level. However, the annotation results using the Kyoto Encyclopedia of Genes and Genomes Automatic Annotation Server predicted a deficiency in the strain's synthesis of alanine, methionine, and biotin. These results were confirmed by essential nutrient factor validation experiments. Furthermore, the optimized medium conditions for caproic acid concentration by strain GD1-1 were (g/l): glucose 30, NaCl 5, yeast extract 10, peptone 10, beef paste 10, sodium acetate 11, L-cysteine 0.6, biotin 0.004, starch 2, and 2.0% ethanol. The optimized fermentation conditions for caproic acid production by C. butyricum GD1-1 on a single-factor basis were: 5% inoculum volume, 35℃, pH 7, and 90% loading volume. Under optimal conditions, the caproic acid concentration of strain GD1-1 reached 5.42 g/l, which was 1.40 times higher than the initial concentration. C. butyricum GD1-1 could be further used in caproic acid production, NXXB pit mud strengthening and maintenance, and artificial pit mud preparation.

• Journal of Dairy Science and Biotechnology
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• v.41 no.3
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• pp.103-112
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• 2023

This study aimed to assess the effectiveness of 10 different pre-enrichment methods using Real-Time polymerase chain reaction (PCR) in support of the FDA method. When the initial Cronobacter spp. (Enterobacter sakazakii) inoculation was 7.2 CFU/g, the Ct values were observed in the following order: 21.37 (Enterobacteriaceae enrichment [EE] broth), 21.95 (brain heart infusion [BHI]), 22.72 (tryptic soy broth [TSB]), 23.02 (violet red bile lactose [VRBL]), 22.31 (TSB-0.1% sodium pyruvate [SP]), 23.43 (distilled water [DW]), 24.34 (phosphate buffered saline [PBS]), 24.95 (nutrient broth [NB]), 25.82 (TSB-0.6% yeast extract [YE]), and 28.27 (violet red bile glucose [VRBG]). For an inoculation of 1.82% CFU/g of Cronobacter spp. (E. sakazakii), the Ct values were recorded in this sequence: 20.34 (EE broth), 22.16 (TSB-0.6% YE), 22.37 (BHI), 22.71 (VRBL), 22.88 (TSB), 23.01 (DW), 23.19 (NB), 23.79 (TSB-0.1% SP), 24.66 (VRBG), and 24.70 (PBS). Finally, when the inoculum of Cronobacter spp. (E. sakazakii) was 0.182 CFU/g, the Ct values followed this order: 21.93 (VRBL), 23.07 (TSB-0.6% YE), 23.31 (DW), 23.47 (PBS), 23.70 (BHI), 24.14 (TSB-0.1% SP), 25.14 (TSB), 29.00 (VRBG), 31.55 (EE broth), and were undetected in the case of NB. Consequently, these results indicate that there were no significant differences among the 10 different pre-enrichment broths. Future studies should focus on exploring pre-enrichment broths that can improve the limit of detection at very low Cronobacter spp. (E. sakazakii) concentrations and enhance the selective recovery of Cronobacter spp. (E. sakazakii) under acid, antibiotic, cold, and heat damage conditions.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.330-339
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• 2024

Corn cobs were fermented with Aspergillus niger to produce soluble dietary fiber (SDF) of high quality and excellent food safety. In this work, the fermentation process was optimized by single-factor test and response surface methodology (RSM). The optimal fermentation conditions were determined to be a material-liquid ratio of 1:30, an inoculum concentration of 11%, a temperature of 32℃, a time of 6 days, and a shaking speed of 200 r/min. Under these conditions, the SDF yield of corn cob increased from 2.34% to 11.92%, and the ratio of soluble dietary fiber to total dietary fiber (SDF/TDF) reached 19.08%, meeting the requirements for high-quality dietary fiber (SDF/TDF of more than 10%). Scanning electron microscopy (SEM) and Fourier-transformed infrared spectroscopy (FT-IR) analysis revealed that the fermentation effectively degraded part of cellulose and hemicellulose, resulting in the formation of a loose and porous structure. After fermentation the water swelling capacity, water-holding capacity, and oil-holding capacity of the corn cob SDF were significantly improved and the adsorption capacity of glucose, cholesterol, and nitrite ions all increased by more than 20%. Moreover, the total phenolic content increased by 20.96%, which correlated with the higher antioxidant activity of SDF. Overall, the fermentation of corn cobs by A. niger increased the yield and enhanced the functional properties of dietary fiber (DF) as well.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.66-76
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• 2014

Resistance of one hundred commercialized cultivars of chili pepper to four isolates of Phytophthora capsici was evaluated under controlled environmental conditions. The cultivars are commercialized as resistant (59%) and susceptible (41%) to Phytophthora blight in Korea. Mean disease severities of the cultivars on P. capsici MY-1, KPC-1, JHAI1-7, and KPC-7 isolates were 37, 55, 60, and 74%, respectively. In addition, 38 for MY-1, 48 for KPC-1, 56 for JHAI1-7, and 76 cultivars for KPC-7 showed susceptibility. To P. capsici MY-1, the weakest pathogenicity isolate among them, 59 cultivars represented high resistance. By contrast, only six cultivars showed high resistance to P. capsici KPC-7, the strongest isolate. Furthermore, resistance of most cultivars except for three cultivars was negatively correlated with the virulence of P. capsici isolates. And isolate-specific resistance of the chili pepper cultivars could not be found. Among them, six cultivars showing resistance to all the tested isolates were selected for further study. The development of Phytophthora blight on the six cultivars according to inoculum density ($5{\times}10^4$ to $1.5{\times}10^6$ sporangia/pot) and incubation temperature (25 to $30^{\circ}C$) after inoculation of P. capsici was tested. Resistance of the cultivars to P. capsici KPC-1 and JHAI1-7, moderately pathogenic isolates, was hardly affected. But to KPC-7 isolate, the highly resistant cultivars showed susceptiblility or moderate resistance when the seedlings were inoculated with inoculum density of $1.5{\times}10^6$ sporangia/pot and incubated at 28 to $30^{\circ}C$. From these results, it is likely that resistance of chili pepper cultivars to Phytophthora blight is affected by the virulence of P. capsici isolate.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.883-890
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• 2015

The soilborne fungus Fusarium oxysporum f. sp. lilii (Fol) is a serious threat to all lily cultivars, especially infecting bulbs and flowers. It has become increasingly important to develop varieties resistant against the bulb rot disease. Genetic diversity of cultivars and reliable screening methods are required for this purpose. Here, an efficient in vitro screening system for evaluating resistance to Fol in 38 in vitro-grown lily plants was investigated. Various factors including culture conditions of Fol, inoculum density, appropriate plant materials, inoculation method and duration, and incubation period of plant materials after inoculation were combined to optimize the screening method. As a result, we suggest optimal conditions for an in vitro screening system for the selection of Fol-resistant lily cultivars as follows. Fol was grown on potato dextrose agar (PDA) medium for 6 days at $25^{\circ}C$ in darkness and used as working inoculation. Spore suspensions were prepared (inoculum density: $1.0{\times}10^4$ $spores{\cdot}mL^{-1}$), and then leaf segments $1.5{\times}2.0cm^2$ were inoculated by dipping for 22 hours at $25^{\circ}C$ in dark. Later, leaves were cultured on 0.6% agar plates at $25^{\circ}C$ and 50% humidity with a photoperiod of 16 hours light/8 hours dark (fluence rate of $40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) to examine the progress of bulb rot. After 7 days, disease levels were classified into indices 1 (no symptom) to 6 (serious bulb rot). Soil inoculation of Fol carried out with resistant or susceptible lily cultivars that had been selected through in vitro screening confirmed the reproducibility of results. Therefore, the in vitro screening method established in this study is efficient and reliable for selection of lily cultivars resistant against bulb rot disease.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.179-185
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• 1992

Rhizobium meliloti populated in five Korean pasture soils were characterized by symbiotic effectiveness and intrinsic antibiotic resistance using whole-soil inoculum and 11 antibiotics, respectively. Most probable number (MPN) of naturalized rhizobia counted with alfalfa Vernal[Medicago sativa (L.)] as a host ranged $1.7{\times}10^2\;cells/g$. soil(Chunghyo, Kyeongiu)-$1.0{\times}10^5\;cells/g$. soil(Gampo, Kyeongiu) and ended to be positively associated with soil pH. On the whole, the effectiveness of population as compared to TAL mix inoculum (TAL 380+TAL 1372+TAL 1373) was very low. Nevertheless, there were two highly effective strains, YCK 539 and YCK 542, which were not inferior to TAL 1372, from Ogpo, Dalseong among the total of 30 of 6 isolates per each soil. As long as mean $N_2$ fixing ability of each soil isolate, the isolates from Hyeongog, Kyeonju were outstanding and the rest were in order of Ogpo, Dalseong>Chunghyo, Kyeongju>Hwaweon, Dalseong>Gampo, Kyeongiu. Isolates as a whole were resistant to erythromycin(67崙), nalidixic acid(77%), and streptomycin sulfate(8051), which had the concentration of $100\;{\mu}g/ml$, $160\;{\mu}g/ml$, and $10\;{\mu}g/ml$, respectively and divided into 14 patterns of resistance. Association between resistances in each soil was not clear. And there was no relationship of resistance pattern to effectiveness. The best effective strain YCKa 542 exclusively fell into No. X pattern having resistance to erythromycin, nalidixic acid, and neomycin sulfate.