• Journal of Korean Academy of Oral Health
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• v.41 no.1
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• pp.22-27
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• 2017

Objectives: Dental plaque is composed of 700 bacterial species. It is known that some oral microorganisms produce porphyrin, and thus, they emit red fluorescence when illuminated with blue light at a specific wavelength of <410 nm. Porphyromonas gingivalis belongs to the genus Porphyromonas, which is characterized by the production of porphyrin. The aim of this study was to evaluate red fluorescence emission of some oral microorganisms interacting with P. gingivalis. Methods: Five bacterial strains (P. gingivalis, Streptococcus mutans, Lactobacillus casei, Actinomyces naeslundii, and Fusobacterium nucleatum) were used for this study. Tryptic soy agar medium supplemented with hemin, vitamin K3, and sheep blood was used as a growth medium. The fluorescence emission of bacterial colonies was evaluated under 405 nm-wavelength blue light using a Quantitative Light-induced Fluorescence Digital (QLF-D) camera system. Each bacterium was cultured alone and co-cultured in close proximity with P. gingivalis. The red/green (R/G) ratio of fluorescence image was calculated and the differences of R/G ratio according to each growth condition were compared using the Mann-Whitney test (P<0.05). Results: Single cultured S. mutans, L. casei and A. naeslundii colonies emitted red fluorescence (R/G ratio=$2.15{\pm}0.06$, $4.31{\pm}0.17$, $5.52{\pm}1.29$, respectively). Fusobacterium nucleatum colonies emitted green fluorescence (R/G ratio=$1.36{\pm}0.06$). The R/G ratios of A. naeslundii and F. nucleatum were increased when P. gingivalis was co-cultured with each bacterium (P<0.05). In contrast, the R/G ratios of S. mutans and L. casei were decreased when P. gingivalis was co-cultured with each bacterium (P=0.002, 0.003). Conclusions: This study confirmed that P. gingivalis could affect the red fluorescence of other oral bacteria under 405 nm-wavelength blue light. Our findings concluded that P. gingivalis has an important role for red fluorescence emission of dental biofilm.

• Research in Plant Disease
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• v.22 no.4
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• pp.293-296
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• 2016

In late June 2016, stalk rot symptoms were observed on five vatieties of sorghum (Sorghum bicolar) at organic paddy-upland rotation system in Anseong city, Korea. The initial symptom on stalk surfaces was red color with a dark red spot lesion. A fungus was isolated from the initial lesion, and cultured on potato dextrose agar. Size of microconidia mostly extend to $5-19{\times}2-{\mu}m$ in culture, with 0-1 septa and macroconidia extend to $29-52{\times}3-4{\mu}m$ with 4-6 septa. Pathogenicity was investigated using conidial suspension spray to seedling of sorghum. After 3 days of inoculation, the dark red lesion was produced on stalks. On the basis of mycological characteristics, pathogenicity, and internal transcribed spacer (ITS) rDNA sequence analysis, this fungus was identified as Fusarium thapsinum. This is the first report of stalk rot on sorghum caused by F. thapsinum in Korea.

• The Korean Journal of Mycology
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• v.38 no.1
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• pp.75-79
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• 2010

A total of 25 isolates of Fusarium fujikuroi were obtained from diseased rice plants in Korea from 2006 to 2007 to assess their resistance against fungicides prochloraz and benomyl + thiram. Minimal inhibitory concentration (MIC) values of F. fujikuroi isolates were examined by agar dilution method. Most of the isolates were sensitive to the fungicides. Out of 25 isolates, six were resistant to prochloraz and three to benomyl + thiram. In addition, the isolates CF245, CF249 and CF337 showed resistant to both fungicides. The progenies ($F_1$ isolates) obtained through two different crosses between sensitive parental isolates(CF202, CF232 and CF179) and resistant parental isolate (CF337) were evaluated for their mycelial growth at different temperatures and resistance against fungicides. Mycelial growth rate of $F_1$ isolates originated from CF202 $\times$ CF232 was similar to the parental isolates. However mycelial growth rate of $F_1$ isolates originated from CF179 $\times$ CF337 was faster than their parent isolates. In case of prochloraz, distribution ratio of sensitivity(S) to resistance(R) against to the fungicide of $F_1$ isolates originated from CF202 $\times$ CF232 and CF179 $\times$ CF337 was 86 : 14 and 78 : 22, respectively. In case of benomyl+thiram, all the $F_1$ isolates originated from CF202 $\times$ CF232 were sensitive to the fungicide, however ratio of sensitivity(S) to resistance(R) against to the fungicide of $F_1$ isolates originated from CF179 $\times$ CF337 was 35 : 65.

• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.135-139
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• 2014

Pathogenic E. coli associated post-weaning diarrhea (PWD) and edema disease are common diseases in commercially-housed weanling pigs. An enterotoxigenic E. coli (ETEC) oral challenge model has been used to mimic the physiological responses observed in commercial conditions. However, an oral challenge procedure has two major limitations: (1) the ETEC cell density is unknown at the point of oral inoculation, and (2) blending ETEC with traditional TSB (trypticase soy broth) is not palatable and hence decreases acceptability by piglets. Therefore, the purposes of this study were to (1) establish a regression equation that can be used for estimation of ETEC concentration in dilution media using the spectrophotometric measurement of cell density; and (2) examine survival of ETEC after blending either with TSB, sweetener or dextrose. A strain of ETEC (serogroup beta-hemolytic E. coli O149; K91; F4; toxins LT, STa, STb) was grown in TSB for 3.5 hours, centrifuged, the supernatant was discarded, and the ETEC pellet was then blended either with TSB (100 mL), sweetener (60 mL TSB + 40 mL fruit flavored concentrate), or dextrose (50 mL TSB + 50 mL dextrose; 0.5g/mL dextrose). Cell density was measured using the colorimetric method and also plated on a 5% sheep blood agar for counting of ETEC colony forming units at 0, 5, 35, 65 and 125 min after blending. The optical density at 600 nm explained 83% of ETEC colony forming units, indicating that the established linear equation (y= 6E+08x - 4E+07, P<0.004) can be used for robust quantification of ETEC cell density in TSB, sweetener and dextrose media. When ETEC was blended with sweetener and dextrose, survival of ETEC was decreased by 45% and 72% within 5 min post-blending. Therefore, further research is required to find out the suitable medium that has potential to improve palatability without compromising survival of ETEC.

• Journal of Ginseng Research
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• v.36 no.3
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• pp.291-297
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• 2012

Ginsenoside (ginseng saponin), the principal component of ginseng, is responsible for the pharmacological and biological activities of ginseng. We isolated lactic acid bacteria from Kimchi using esculin agar, to produce ${\beta}$-glucosidase. We focused on the bio-transformation of ginsenoside. Phylogenetic analysis was performed by comparing the 16S rRNA sequences. We identified the strain as Lactobacillus (strain 6105). In order to determine the optimal conditions for enzyme activity, the crude enzyme was incubated with 1 mM ginsenoside Rb1 to catalyse the reaction. A carbon substrate, such as cellobiose, lactose, and sucrose, resulted in the highest yields of ${\beta}$-glucosidase activity. Biotransformations of ginsenoside Rb1 were analyzed using TLC and HPLC. Our results confirmed that the microbial enzyme of strain 6105 significantly transformed ginsenoside as follows: Rb1${\rightarrow}$gypenoside XVII, Rd${\rightarrow}$F2 into compound K. Our results indicate that this is the best possible way to obtain specific ginsenosides using microbial enzymes from 6105 culture.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.168-173
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• 2013

Apple ring rot disease, caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., is one of the most important diseases on apple fruits. In this study, strain 9001 isolated from healthy apple fruits from an infested orchard was evaluated for its biocontrol activity against apple ring rot in vitro and in vivo. Strain 9001 showed obvious antagonistic activity to B. dothidea YL-1 when plated on potato dextrose agar. Soaking healthy apples in the bacterial suspensions of strain 9001 prior to artificial inoculation of fungal pathogen resulted in a dramatic decrease in disease incidence when compared to the control. Moreover, either field application in the growth season or postharvest treatment of apples from infected orchards with bacterial suspensions of strain 9001 resulted in significantly reduced disease incidence within the storage period for 4 months at room temperature. Based on the phylogenetic analysis of 16S rRNA and the gyrA gene, strain 9001 was identified as Bacillus amyloliquefaciens. These results indicated that B. amyloliquefaciens 9001 could be a promising agent in biocontrol of apple ring rot on fruit, which might help to minimize the yield loss of apple fruit during the long postharvest period.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.526-534
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• 2019

Chlorella gloriosa (Chlorellaceae, Trebouxiophyceae) was isolated from seawater off the coast of the Dokdo Islands in Korea. An axenic culture was established using the streak-plate method on f/2 agar media supplemented with antibiotics, allowing identification of the isolate by morphological, molecular, and physiological analyses. The morphological characteristics observed by light and electron microscopy revealed typical morphologies of C. gloriosa species. The molecular phylogenetic inference drawn from the small-subunit 18S rRNA sequence verified that the microalgal strain belongs to C. gloriosa. Additionally, gas chromatography-mass spectrometry analysis showed that the isolate was rich in nutritionally important omega-3 and -6 polyunsaturated fatty acids and high-performance liquid chromatography analysis revealed that the high-value antioxidants lutein and violaxanthin were biosynthesized as accessory pigments by this microalga, with arabinose, galactose, and glucose as the major monosaccharides. Therefore, in this study, a Korean marine C. gloriosa species was discovered, characterized, and described, and subsequently added to the national culture collection.

• Applied Biological Chemistry
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• v.38 no.4
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• pp.359-363
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• 1995

New ten N-[1-(benzotriazol-1-yl)alkyl]aniline(4) derivatives were synthesized and the crystal structure of 4h was shown by X-ray crystallography and the absolute configuration has been assigned as S form. The molecule crystallizes in the monoclinic system, space group $P2_{1}/n$. And the molecules in the crystal are linked with each other through the hydrogen bond $(N_{11}-H_{11}{\cdots}N3)$ with distance $2.300(11){\AA}$ The fungicidal activity($pI_{50}$) in-vitro against Botrytis cineria (BC), Phytophthora casici (PC) and Sclerotium cepinorum (SC) were determined by the agar dilution method. The structure activity ralationships (SAR) between structure of 4 and the activity were studied using a physicochemical parameters of substituents and multiple regression technique. Among these compounds, only the bromo group substituent(4f) showed higher activity, which depend on the hydrophobic(${\pi}$) of substituents. The relative orders of the activity are SC>BC> and PC, respectively. This implies that the activity is affected by the hydrophobic(${\pi}$) nature of the Z group rather than the X group. Linear free energy relationships(LFER) on the fungicidal activity with substituents has been also discussed.

• Research in Plant Disease
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• v.24 no.1
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• pp.75-80
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• 2018

From 2014 to 2016, Fusarium wilt disease was found on fassionfruit in Iksan and Jeju, Korea. Symptoms included wilting of foliage, drying and withering of leaves, and stunting of the plants. The infected plants eventually died during growth. Colonies on potato dextrose agar were pinkish white, and felted with cottony and aerial mycelia with 35 mm after one week. Macroconidia were falcate to almost straight, thin-walled and usually 2-3 septate. Microconidia were usually formed on monophialides of the hyphae and were hyaline, smooth, oval to ellipsoidal, aseptate or medianly 1-septate, very occasionally 2-septate, slightly constricted at the septa, $3-12{\times}2.5-6{\mu}m$. On the basis of the morphological characteristics and phylogenetic analyses of two molecular markers, internal transcribed spacer rDNA and translation elongation factor $1{\alpha}$, the fungus was identified as Fusarium oxysporum. Pathogenicity of a representative isolate was proved by artificial inoculation, fulfilling Koch's postulates. To our knowledge, this is the first report on the occurrence of F. oxysporum on fassionfruit in Korea.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.129-141
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• 2001

When oral microorganisms were sampled from occlusal surfaces of caries and non-caries teeth, $3.43\times10^5$ CFU and $3.47\times10^3$ CFU of bacteria were counted on MSB agar plates, respectively. All the 20 colonies isolated from a caries surface were Streptococcus mutans but, only two of 20 colonies were identified as Streptococcus mutans by API test. S. mutans SM1 from caries tooth and S. mutans SM2 from non-caries tooth showed the same results except for $\alpha-galactosidase$ activity on sugar fermentation tests and biochemical tests. For the bacterial replication, both SM1 and SM2 were actively multiplicated at pH 5.5. And the viability of SM1 was high at 20% of sucrose, while that of SM2 was high at 5% of sucrose in the media. SM1 actively replicated at 16mM of $CaCl_2$, 160mM of KCl, and 6.4mM of $MgCl_2$, and the replication of SM2 was increased at 16mM of $CaCl_2$, 40mM of KCl, 6.4mM of $MgCl_2$. At 1mM of sodium bicarbonate and sodium phosphate, both bacteria were actively multiplicated. SM1 and SM2 were actively replicated at 1mM and 10mM of Tris, respectively. For potassium phosphate buffer, SM1 grew well proportionally to the concentration up to 100mM, while the growth of SM2 were inhibited by the increase of concentration. The 4.6 kb of gtf gene was amplified with a pair of primer, gtfB-F961 and gtfC-R5574 by polymerase chain reaction from the chromosomal DNA of SM1 and SM2. When 4.6kb bands were eluted from gel and were treated with restriction enzyme, EcoR I produced the same RFLP like 0.8kb and 3.8kb of DNA fragments for S. mutans GS-5, SM1 and SM2. By Hind III, the PCR products weren't digested for S. mutans GS-5 and SM1, but 3 fragments such as 2.4kb, 1.8kb and 400bp were examined for SM2. These results indicated the difference between gtf genes of SM1 and SM2. BamH I treatment showed 4 fragments for SM1 and SM2, while the 3 fragments for S. mutans GS-5. The PCR products were not digested by Kpn I, Sma I, Xho I and Pst I.