• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.327-332
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• 1994

Optimum conditions for the production of acetoin and ammonia as the precursors of tetramethylpyrazine(TMP) were determined using Lactococcus lactis subsp. lactis biovar. diacetylactis FC1 in a modified Lactose-citrate broth containing galactose, citrate, and arginine. The cell growth and the productivity of acetoin and ammonia were remarkably increased in an aerobic culture with 10 $\mu M$ of hematin. For the optimum conditions of acetoin and ammonia production, the concentration of citrate and arginine were adjusted to 156 mM and 50 mM after 18 hr cultivation, and citrate and galactose to 156 mM and 50 mM after 36 hr cultivation, respectively. In these conditions, acetoin and ammonia were produced to the final concentration of 127 mM and 195 mM, which were the highest concentations, respectively. The optimum conditions of the TMP production were also determined as follows; 4 hours at 121, pH 8.3, and the maximal yield of TMP under these conditions was 0.81 g/l.

• Research in Plant Disease
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• v.22 no.4
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• pp.276-283
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• 2016

Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) occurred at 202 kiwifruit orchards for the survey period of 2013-2016, of which Psa biovar 2 (Psa2) and Psa biovar 3 (Psa3) were detected at 73 and 129 kiwifruit orchards, respectively. The number of kiwifruit orchards infected by Psa3 in 2016 increased nearly two times compared to 2015. Psa3 was detected from all the kiwifruit cultivars except some kiwiberry cultivars growing in Korea. Yellow-fleshed cultivars Hort16A and Jecy-gold and red-fleshed cultivar Hongyang were highly susceptible to Psa3. Our epidemiological and random amplification of polymorphic DNA analyses indicated that the first Psa3 incidence on Hongyang orchard in Sacheon, Gyoungnam might result from an introduction of Psa3-contaminated pollens from China for artificial pollination in 2014 and recent outbreaks of Psa3 in Sacheon and Goseong, Gyoungnam in 2016 might be due to rapid spread of bacterial canker by secondary infection of Psa3 from Hongyang orchard to neighboring Jecy-gold and Hayward orchards.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.285-287
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• 1991

To produce the tetramethylpyrazine (TMP) flavor compound, Lactococcuss lactis subsp. lactis biovar. diacetilactis (L. diacetilactis) FC1 was cultivated in the TMP medium containing 3% (w/v) of Na-citrate and 6% (w/v) arginine-HC1 as substrates of acetoin and $NH_3$, respectively, which are the two precursors of the TMP. After 19-day fermentation at $34^{\circ}C$, 0.57 g/l or 4.19 mmole/l of the TMP was produced. This was the first result showing that the TMP could be produced by L. diacetilactis.

• Research in Plant Disease
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• v.17 no.3
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• pp.326-333
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• 2011

This study evaluated disease resistance responses of pure lines of tomato plants at various temperature conditions against Ralstonia solanacearum strains isolated from Korea. Evaluation of six tomato lines with various strains of R. solanacearum showed that many strains can infect the resistant lines of tomato plants previously known as highly tolerant to bacterial wilt. One of the most virulent strains, SL341 (race 1 and biovar 4) caused severe infection on all six tomato lines, irrespective of temperature. In contrast, a moderately virulent strain SL1944 (race 1, biovar 4) showed the remarkable difference in disease progress on some resistant lines dependent on temperature. Moneymaker and Bonny Best were susceptible to SL1944 at all tested conditions with different temperature. However, tomato lines, such as Hawaii 7998, Hawaii 7996, Bblocking which were previously known as highly tolerant lines, were severely infected by SL1944 at relatively higher temperature ($35^{\circ}C$ for 14 hr light and $28^{\circ}C$ for 10 hr dark cycle). The disease progress at high temperature was much faster than those at low temprature on the same tomato line and those on Moneymaker and Bonny Best at the same high temprature. This result suggested that R. solanacearum strains isolated in Korea were highly virulent to bacterial wilt resistant tomato lines and some strains may cause severe infection on those plants at higher temperature.

• The Plant Pathology Journal
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• v.33 no.4
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• pp.351-361
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• 2017

Bacterial canker is the largest limiting factor in the cultivation and production of kiwifruit worldwide. Typical symptoms comprise necrotic spots on leaves, canker and dieback on canes and trunks, twig wilting, and blossom necrosis. Pseudomonas syringae pv. actinidiae (Psa), which is the causal agent of kiwifruit bacterial canker, is divided into four biovars based on multilocus sequence analysis of different genes, additional PCR testing of pathogenic genes (argKtox cluster, cfl, and various effector genes), and biochemical and physiological characterization. Bacterial canker caused by Psa biovar 2 designated Psa2 was detected for the first time on the green-fleshed kiwifruit cultivar Hayward in 1988 and the yellow-fleshed kiwifruit cultivar Hort16A in 2006 in Korea. Psa biovar 3 designated Psa3, responsible for the current global pandemics of kiwifruit bacterial canker, began to appear in Korea in 2011 and caused tremendous economic losses by destroying many vines or orchards of yellow-fleshed kiwifruit cultivars in one or several growing seasons. Bacterial canker epidemics caused by both Psa2 and Psa3 are prevalent in Korea in recent years. In this review, we summarize the symptomatology, etiology, disease cycle, diagnosis, and epidemiology of kiwifruit bacterial canker in Korea.

• Research in Plant Disease
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• v.10 no.1
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• pp.58-62
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• 2004

Contamination level and characteristics of Ralstonia solanacearum in soil of greenhouses cultivating tomato plants in Chungbuk province was determined. R. solanacearum was isolated with the semiselective media in 27 greenhouse soil samples out of 133 greenhouses soil investigated, which indicates 20.3 ％ of tomato cultivating greenhouses in Chungbuk contaminated with the bacterial wilt pathogen. Density of R. solanacearum was estimated to 10$^{2.4}$ cfu/g in the contaminated soil. All 71 isolates of R. solanacearum which containing 12 isolates from the diseased tomato plants were race 1, ann 35 isolates of them were biovar 3 and 36 isolates were biovar 4. More than 88％ of 71 isolates were inhibited growth on nutrient agar containing oxolinic acid 0.5 $\mu\textrm{g}$/ml, streptomycin 25 $\mu\textrm{g}$/ml, tetracycline 5 $\mu\textrm{g}$/ml and cupric sulfate 375 $\mu\textrm{g}$/ml (1.5 mM). The 11.3％, 4.2％ and 5.6 ％ of the isolates can grow on nutrient agar containing 10 times more oxolinic acid, streptomycin, tetracycline than minimal inhibitory concentration of the sensitive strains. Five isolates were resistant to 2 bactericides and one isolates was resistant to all 3 bactericides.

• Korean Journal of Microbiology
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• v.35 no.3
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• pp.185-191
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• 1999

This study was conducted to investigate the vibrio flora in an edible shellfish. sunset shelfish. Soletelliim olivacen. which were collected in the estuarine area. Dadaepo near Nakdong River in Korea lkoin January 1997 to November 1997. Including five pathogemc vibrios (Vibrio alginolyticus, Vibrio pamhaemol~~licz~s, Vibrio cholerae non-01. Vibrio vulnificus, and Vihrio jl~~vinlis), a lotal of eight species of vlbr~os (Vi61-io splendidrrs biovar I, Vibrio splendidus biovar 11, Vibrio snlrnonicida and Vibrio tr,~biasllii) were identified from the sunset shellfish by heir biochemical characters. The isolation of Vihrio pamhaemolyricns, which is known not to grow below $15^{\circ}C$, in winter season indicates that the sunset shelllish is one oT the natural owl.- wintering hosts for Vibrio parahuemolyticus.

• Clinical and Experimental Pediatrics
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• v.53 no.12
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• pp.989-993
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• 2010

Although numerous clinical observational studies have been conducted over a period of over 30 years, the clinical significance of $Ureaplasma$ infection is still under debate. The $Ureaplasma$ speices. is a commensal in the female genital tract and considered to have of low virulence; however, $Ureaplasma$ colonization has been associated with infertility, stillbirth, preterm delivery, histologic chorioamnionitis, and neonatal morbidities, including congenital pneumonia, meningitis, bronchopulmonary dysplasia, and perinatal death. Recently, $Ureaplasma$ was subdivided into 2 separate species and 14 serovars. $Ureaplasma$ $parvum$ is known as biovar 1 and contains serovars 1, 3, 6, and 14, and $Ureaplasma$ $urealyticum$ (biovar 2) contains the remaining serovars (2, 4, 5, and 7-13). The existence of differences in pathogenicities of these 14 serovars and 2 biovars is controversial. Although macrolides are the only antimicrobial agents currently available for use in neonatal ureaplasmal infections, in the current clinical field, it is difficult to make decisions regarding which antibiotics should be used. Future investigations involving large, multicenter, randomized, controlled studies are needed before proper recommendations can be made for clinical practice.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.39-46
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• 1994

Pseudomonas fluorescens Biovar III strains S-2 antagonistic to Rhizoctonia solani was subjected to Tn5 mutagenesis by the transposon vector pGS9. Ampicillin and kanamycin resistant (Ampr, Kmr) transconjugants were recovered at a frequency of 1.3$\times$10-7 per initial recipient cell, when recipient cells were washed twice in TE buffer before conjugation. Of the ca. 3000 transconjugants, a frequency of noninhibitory (Inh-), nonfluorescent (Flu-) and auxotorphic (Pro-) mutants were 0.27%, 0.47% and 0.40%, respectively. In these mutants, all Inh- mutants showed the same colony morphology as wild type, whereas all Flu- and Pro- mutants inhibited the growth of R. solani. These mutants were also susceptible to chloramphenicol, indicating only the Tn5 element, except for parts of pGS9, was integrated into the recipient genome. In a Southern blot analysis, the Tn5 element inserted into one site on the chromosome for each of the chosen mutants. However, Tn5 insertion sites of Inh-, and Pro- mutants were differed in each other. These indicate that the genes essential for R. solani inhibition, fluorescent production and auxotrophic are chromosomally located, but not linked to each other.

• The Plant Pathology Journal
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• v.32 no.6
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• pp.545-551
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• 2016

A bacterial pathogen, Pseudomonas syringae pv. actinidiae (Psa), is a causal agent of kiwifruit bacterial canker worldwide. Psa biovar 3 (Psa3) was first detected in 2011 at an orchard in Dodeok-myeon, Goheung-gun, Jeonnam Province in Korea. In this study, we present the results of an epidemiological study regarding Psa3 occurrence on kiwifruit orchards in Korea for the period of 2013 to 2015. Since the first detection of Psa3 in 2011, there was no further case reported by 2013. However, Psa3 was rapidly spreading to 33 orchards in 2014; except for three orchards in Sacheon-si, Gyeongnam Province, most cases were reported in Jeju Island. Entering 2015, bacterial canker by Psa3 became a pandemic in Korea, spreading to 72 orchards in Jeju Island, Jeonnam, and Gyeongnam Provinces. Our epidemiological study indicated that the first Psa3 incidence in 2011 might result from an introduction of Psa3 through imported seedlings from China in 2006. Apart from this, it was estimated that most Psa3 outbreaks from 2014 to 2015 were caused by pollens imported from New Zealand and China for artificial pollination. Most kiwifruit cultivars growing in Korea were infected with Psa3; yellow-fleshed cultivars (Yellow-king, Hort16A, Enza-gold, Zecy-gold, and Haegeum), red-fleshed cultivars (Hongyang and Enza-Red), green-fleshed cultivars (Hayward and Daeheung), and even a kiwiberry (Skinny-green). However, susceptibility to canker differed among cultivars; yellow- and red-fleshed cultivars showed much more severe symptoms compared to the green-fleshed cultivars of kiwifruit and a kiwiberry.