• Journal of Species Research
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• v.10 no.1
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• pp.23-45
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• 2021

For the collection of indigenous prokaryotic species in Korea, 77 strains within the phylum Actinobacteria were isolated from various environmental samples, fermented foods, animals and clinical specimens in 2019. Each strain showed high 16S rRNA gene sequence similarity (>98.8%) and formed a robust phylogenetic clade with actinobacterial species that were already defined and validated with nomenclature. There is no official description of these 77 bacterial species in Korea. The isolates were assigned to 77 species, 31 genera, 18 families, 14 orders and 2 classes of the phylum Actinobacteria. All the strains except one Coriobacteriia strain were affiliated within the class Actinomycetia. Among them, the orders Streptomycetales and Microbacteriales were predominant. A number of strains were isolated from forest soils, riverside soils, and ginseng cultivated soils. Twenty-nine strains were isolated from 'Protected Ecosystem and Scenery Areas'. Morphological properties, basic biochemical characteristics, isolation source and strain IDs are described in the species descriptions.

• Journal of Species Research
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• v.12 no.3
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• pp.212-223
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• 2023

A total of 30 bacterial strains were identified in the classes Betaproteobacteria and Gammaproteobacteria in the study of prokaryotic species in Korea. These strains were isolated from a variety of environmental sources, including soil, tidal flat, mud, wetland, pine cone, seaweed, sea sediment, and brackish water. Phylogenetic analysis showed that isolates were identified based on high 16S rRNA gene sequence similarities (≥98.7%) with the predefined bacterial type species. In this study, we present data on previously unreported species from Korea, including 10 species from three families of one order in the class Betaproteobacteria and 20 species from 12 families of nine order in the class Gammaproteobacteria. Morphological, biochemical characteristics, isolation sources, and NIBR deposit numbers are provided in the description sections.

• Research in Plant Disease
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• v.30 no.1
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• pp.95-98
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• 2024

In a survey conducted in March 2023, Euphorbia hypogaea plants cultivated within greenhouses in Yongin, Korea exhibited water-soaked areas near the stem base, close to the soil. Subsequent isolation from diseased E. hypogaea led to the identification of a bacterial strain, designated as CBNUMPBL-103. The isolate was identified as Dickeya dadantii through sequencing of the 16s rRNA and phylogenetic analysis. The pathogenicity of the isolate was confirmed by inoculating it into healthy E. hypogaea, resulting in the manifestation of similar symptoms observed during the survey. The re-isolated strain recovered from inoculated plants showed a similar morphology with the inoculated strain. This is the first documentation of D. dadantii causing soft rot of E. hypogaea in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.3
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• pp.135-149
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• 2017

In order to obtain promising rice growth-promoting microbial strains that can be used as substitutes for chemical fertilizers, 172 bacterial strains were isolated from rice roots grown in Korean and Russian soils. Out of them, the strains KR076, KR083, KR181 and RRj228 showed plant growth-promoting activities on maize seedlings. Bacillus megaterium KR076 and Bacillus sp. KR083 showed both nitrogen-fixing and plant growth-promoting activities, while Rhizobium sp. KR181 and Pseudomonas sp. RRj228 appeared to support only plant growth-promotion, but not $N_2$ fixation. Especially, RRj228 showed high growth promoting activity at low concentrations. Inoculation studies with KR083 and RRj228 revealed a high affinity to the Japonica rice variety such as Junambyeo than the Korean Tongil type variety such as Arumbyeo. Both KR083 and RRj228 strains showed rhizoplane and/or endophytic colonization in Japonica and Tongil types rice when soaked with the bacterial suspension of $1.1{\times}10^5cfu\;ml^{-1}$ for six and twelve hours. However, the total bacterial cell numbers were higher in the roots of Japonica variety than in the Tongil type. In inoculation trials with Daesanbyeo rice variety, the seedlings inoculated with KR181 and RRj228 at the rate of $2.0{\times}10^6cfu\;ml^{-1}$ showed yield increment of 35% and 33% (p < 0.01), respectively, so that they contributed to the replacement of chemical fertilizer at half doses of N, $P_2O_5$, and $K_2O$ in pots. In Junambyeo rice seedlings, the strain RRj228, when inoculated with a cell suspension of $1.8{\times}10^6cfu\;ml^{-1}$, promoted 3.4% higher yield at 70% dose than at a full dose level of N $110kg\;ha^{-1}$ in field. These results suggest that the rhizobacteria KR181 and RRj228 are prospective strains for enhancing rice performance.

• Journal of Life Science
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• v.22 no.2
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• pp.177-183
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• 2012

Bacterial wilt (brown rot) caused by Ralstonia solanacearum (Rs) is one of the most devastating bacterial plant diseases in potatoes. To isolate bacterial wilt disease resistance-related genes from the potato, the StACRE (HM749652) gene was isolated and a sequenced search was performed using functional orthologs of Solanaceae from potatoes. StACRE is homologous to the tobacco NtACRE 132 protein and belongs to the ATL family involved in ubiquitination. To analyze the expression pattern of this gene, RT-PCR was performed with potato treated with salicylic acid (SA) and Rs (KACC 10722). StACRE was strongly induced 3 hours after treatment with SA and 12 hours after infection with Rs. To investigate its biological functions in the potato, we constructed a vector for overexpression in the potato by the Gateway system, and then generated transgenic potato plants. The gene expression of transgenic potato was analyzed by northern blot analysis. In the results of disease resistance assay in relation to bacterial wilt, StACRE overexpressed transgenic potato plants were shown to have more resistance than wild-type potato.

• Journal of Life Science
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• v.24 no.5
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• pp.522-531
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• 2014

Seasonal variations in the bacterial community of Gwangyang Bay seawater were analyzed using both isolation and cultivation-independent methods. Amplified rDNA restriction analysis was applied to 200 bacterial isolates. Bacterial isolates were composed of four phyla: Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. Pyrosequencing was conducted, in addition to denaturing gradient gel electrophoresis (DGGE) of genomic DNA extracted directly from the water samples. The bacterial sequences obtained by pyrosequencing of 16S rRNA genes consisted of 24 phyla in the spring and summer, 39 in the fall, and 32 in the winter. The diversity index was high in the fall, whereas the dominancy index was high in the spring. In the spring, phylum Firmicutes was dominant, whereas phylum Proteobacteria dominated in the other three seasons. The second most dominant phyla were Proteobacteria in the spring, Firmicutes in the summer, and Bacteroidetes both in the fall and winter. Bacilliaceae was the most predominant family in the spring. Rhodobacteraceae and Bacilliaceae dominated in the summer, and Rhodobacteraceae dominated in the winter. Neither was dominant in the fall Twenty-seven bands purified from DGGE profiles were cloned and analyzed phylogenetically. In the spring, phylum Firmicutes dominated, followed by Proteobacteria. Proteobacteria dominated in all other seasons. Thus, two cultivation-independent methods for determination of seasonal variation patterns at the phylum level were in accordance with each other.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.341-351
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• 2019

In this study, we investigated anti-oxidative and anti-bacterial constituents from Rhododendron weyrichii leaves. DPPH and ABTS⁺ radical scavenging activities were screened for the ethanol extract and solvent fractions. Potent scavenging activities were appeared from the extract, ethyl acetate (EtOAc) and n-butanol (BuOH) fractions. Upon the anti-bacterial tests using Staphylococcus epidermidis and Propionibacterium acnes, extract, n-hexane (Hex) and EtOAc fractions showed strong activities. To isolate the active constituents, the EtOAc fraction was further purified to afford five phytochemicals; ursolic acid (1), corosolic acid (2), asiatic acid (3), astragalin (4) and isoquercetin (5). All of the compounds 1-5 were isolated for the first time from this plant. Among the isolates, the compound 4 and 5 showed strong DPPH and ABTS⁺ radical scavenging activities. Also, compound 3 exhibited the most potent anti-bacterial activity. In addition, the content of astragalin isolated from this plant was determined by UPLC and the quantity was about 8.1 mg/g for the 70% ethanol extract and 34.8 mg/g for the EtOAc fraction. Based on these results, it is concluded that R. weyrichii extract could be potentially applicable as anti-oxidative and anti-bacterial ingredients in cosmetic formulations.

• Journal of Life Science
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• v.25 no.2
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• pp.189-196
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• 2015

Bacterial diversity was studied in the rhizosphere of Suaeda japonica Makino, which is native to Suncheon Bay in South Korea. Soil samples from several sites were diluted serially, and pure isolation was performed by subculture using marine agar and tryptic soy agar media. Genomic DNA was extracted from 29 pure, isolated bacterial strains, after which their 16S rDNA sequences were amplified and analyzed. Phylogenetic analysis was performed to confirm their genetic relationship. The 29 bacterial strains were classified into five groups: phylum Firmicutes (44.8%), Gamma proteobacteria group (27.6%), Alpha proteobacteria group (10.3%), phylum Bacteriodetes (10.3%), and phylum Actinobacteria (6.8%). The most widely distributed genera were Bacillus (phylum Firmicutes), and Marinobacterium, Halomonas, and Vibrio (Gamma proteobacteria group). To confirm the bacterial diversity in rhizospheres of S. japonica, the diversity index was used at the genus level. The results show that bacterial diversity differed at each of the sampling sites. These 29 bacterial strains are thought to play a major role in material cycling at Suncheon Bay, in overcoming the sea/mud flat-specific environmental stress. Furthermore, some strains are assumed to be involved in a positive interaction with the halophyte S. japonica, as rhizospheric flora, with induction of growth promotion and plant defense mechanism.

• Research in Plant Disease
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• v.12 no.2
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• pp.129-133
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• 2006

A bacterial disease of small red bean (Phaseolus angularis) was observed on field-grown plants in Suwon in year 2003. Leaf symptoms initially appeared as water-soaked spots that gradually enlarged, became flaccid and necrotic and were often bordered by a small zone of lemon yellow tissue. In the case of severe infection, dead leaves were defoliated. Pod symptoms consisted of the lesions that were generally circular, slightly sunken and dark reddish brown. Isolation made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Three bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old small red bean plants sprayed with bacterial suspensions containing $10^8 cfu/ml$ of phosphate buffered saline. The representative Xanthomonas strains isolated from small red bean were compared with X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans type strains for fatty acid profiles, biochemical tests and metabolic fingerprints using Biolog GN2 microplate, showing that all outcomes were indistinguishable between our isolates and reference strains. Two of three strains produced a melanin-like brown pigment extracellularly on King's medium B agar. These results suggest that this new small red bean disease observed in Suwon is bacterial fuscous blight caused by X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans.

• Korean Journal of Veterinary Research
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• v.52 no.4
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• pp.285-288
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• 2012

Salmonella I 4,[5],12:i:- was a monophasic variant of Salmonella (S.) Typhimurium and notorious for re-emerging candidate which would replace S. Typhimurium DT104 for antibiotic resistance. Recently, isolation rate was increased on human and industrial animals but there was no case in domestic animals but human in Korea. This was first isolation case from domestic animals in Korea. The five isolates from feces of duck (n = 3), chicken (n = 1), and wild bird (n = 1) showed antibiotic resistance against cephems and aminoglycosides. These means that the spread of emerging bacterial pathogens to domestic animals and the need of systemic management for Salmonella I 4,[5],12:i:-.