• Korean Journal of Microbiology
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• v.46 no.3
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• pp.255-261
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• 2010

The bacterial community structure associated with two marine sponges, Hyrtios sp. 604 and Callyspongia sp. 612 collected from the South Pacific Ocean were analyzed by 16S rDNA-denaturing gradient gel electrophoresis (DGGE). The phylogenetic analysis showed that the bacterial community associated with Hyrtios sp. 604 contained diverse bacterial groups such as Chloroflexi, Firmicutes, Cyanobacteria, Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, and Acidobacteria. Callyspongia sp. 612 harbored Chloroflexi, Cyanobacteria, Alphaproteobacteria, and Gammaproteobacteria. Hyrtios sp. 604 belonging to genus Hyrtios known to produce natural products showed greater bacterial diversity than Callyspongia sp. 612. Phylum Actinobacteria was shown to be one of dominant bacterial groups in Hyrtios sp. 604. Although the same phyla of bacteria were found in both sponge species, the spongeassociated predominant bacterial groups differed between the two sponges with different chemical characteristics from the same geographical location. Uncultured bacteria represented over 90% of the bacteria diversity present in all bacterial communities of the sponges.

• Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.28.1-28.7
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• 2016

Background: Significant increases in the bacterial resistance to various antibiotics have been found in fish farms. Non-antibiotic therapies for infectious diseases in aquaculture are needed. In recent years, light-emitting diode technology has been applied to the inactivation of pathogens, especially those affecting humans. The purpose of this study was to assess the effect of blue light (wavelengths 405 and 465 nm) on seven major bacterial pathogens that affect fish and shellfish important in aquaculture. Results: We successfully demonstrate inactivation activity of a 405/465-nm LED on selected bacterial pathogens. Although some bacteria were not fully inactivated by the 465-nm light, the 405-nm light had a bactericidal effect against all seven pathogens, indicating that blue light can be effective without the addition of a photosensitizer. Photobacterium damselae, Vibrio anguillarum, and Edwardsiella tarda were the most susceptible to the 405-nm light (36.1, 41.2, and $68.4J\;cm^{-2}$, respectively, produced one log reduction in the bacterial populations), whereas Streptococcus parauberis was the least susceptible ($153.8J\;cm^{-2}$ per one log reduction). In general, optical density (OD) values indicated that higher bacterial densities were associated with lower inactivating efficacy, with the exception of P. damselae and Vibrio harveyi. In conclusion, growth of the bacterial fish and shellfish pathogens evaluated in this study was inactivated by exposure to either the 405- or 465-nm light. In addition, inactivation was dependent on exposure time. Conclusions: This study presents that blue LED has potentially alternative therapy for treating fish and shellfish bacterial pathogens. It has great advantages in aspect of eco-friendly treating methods differed from antimicrobial methods.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1613-1620
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• 2012

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops. Since there is no promising control strategy for bacterial wilt, phage therapy could be adopted using virulent phages. We used phage PE204 as a model lytic bacteriophage to investigate its biocontrol potential for bacterial wilt on tomato plants. The phage PE204 has a short-tailed icosahedral structure and double-stranded DNA genome similar to that of the members of Podoviridae. PE204 is stable under a wide range of temperature and pH, and is also stable in the presence of the surfactant Silwet L-77. An artificial soil microcosm (ASM) to study phage stability in soil was adopted to investigate phage viability under a controlled system. Whereas phage showed less stability under elevated temperature in the ASM, the presence of host bacteria helped to maintain a stable phage population. Simultaneous treatment of phage PE204 at $10^8$ PFU/ml with R. solanacearum on tomato rhizosphere completely inhibited bacterial wilt occurrence, and amendment of Silwet L-77 at 0.1% to the phage suspension did not impair the disease control activity of PE204. The biocontrol activities of phage PE204 application onto tomato rhizosphere before or after R. solanacearum inoculation were also investigated. Whereas pretreatment with the phage was not effective in the control of bacterial wilt, post-treatment of PE204 delayed bacterial wilt development. Our results suggested that appropriate application of lytic phages to the plant root system with a surfactant such as Silwet L-77 could be used to control the bacterial wilt of crops.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.805-814
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• 2008

Liming of acidic soils can prevent aluminum toxicity and improve crop production. Some maize lines show aluminum (Al) tolerance, and exudation of organic acids by roots has been considered to represent an important mechanism involved in the tolerance. However, there is no information about the impact of liming on the structures of bacterial and fungal communities in Cerrado soil, nor if there are differences between the microbial communities from the rhizospheres of Al-tolerant and Al-sensitive maize lines. This study evaluated the effects of liming on the structure of bacterial and fungal communities in bulk soil and rhizospheres of Al-sensitive and Al-tolerant maize (Zea mays L.) lines cultivated in Cerrado soil by PCR-DGGE, 30 and 90 days after sowing. Bacterial fingerprints revealed that the bacterial communities from rhizospheres were more affected by aluminum stress in soil than by the maize line (Al-sensitive or Al-tolerant). Differences in bacterial communities were also observed over time (30 and 90 days after sowing), and these occurred mainly in the Actinobacteria. Conversely, fungal communities from the rhizosphere were weakly affected either by liming or by the rhizosphere, as observed from the DGGE profiles. Furthermore, only a few differences were observed in the DGGE profiles of the fungal populations during plant development when compared with bacterial communities. Cloning and sequencing of 16S rRNA gene fragments obtained from dominant DGGE bands detected in the bacterial profiles of the Cerrado bulk soil revealed that Actinomycetales and Rhizobiales were among the dominant ribotypes.

• Journal of Microbiology and Biotechnology
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• v.32 no.4
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• pp.419-429
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• 2022

American ginseng (Panax quinquefolium L.) is a perennial herbaceous plant widely cultivated in China, Korea, the United States, and Japan due to its multifunctional properties. In northwest China, transplanting after 2-3 years has become the main mode of artificial cultivation of American ginseng. However, the effects of the cultivation process on the chemical properties of the soil and bacterial community remain poorly understood. Hence, in the present study, high-throughput sequencing and soil chemical analyses were applied to investigate the differences between bacterial communities and nutrition driver factors in the soil during the cultivation of American ginseng. The responses of soil nutrition in different ecological niches were also determined with the results indicating that the cultivation of American ginseng significantly increased the soluble nutrients in the soil. Moreover, the bacterial diversity fluctuated with cultivation years, and 4-year-old ginseng roots had low bacterial diversity and evenness. In the first two years of cultivation, the bacterial community was more sensitive to soil nutrition compared to the last two years. Proteobacteria, Actinobacteria, Gemmatimonadetes, Acidobacteria, Firmicutes, and Bacteroidetes dominated the bacterial community regardless of the cultivation year and ecological niche. With the increase of cultivation years, the assembly of bacterial communities changed from stochastic to deterministic processes. The high abundance of Sphingobium, Novosphingobium, and Rhizorhabdus enriched in 4-years-old ginseng roots was mainly associated with variations in the available potassium (AK), total phosphorus (TP), total potassium (TK), and organic matter (OM).

• The Plant Pathology Journal
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• v.17 no.5
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• pp.249-256
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• 2001

Xanthomonas axonopodis pv. glycines 8ra produces a bacteriocin called glycinecinA, which specifically inhibits the growth of bacteria belonging to Xanthomonas species. GlycinecinA was produced by culturing Escherichia coli DH5 containing biosynthetic genes for glycinecinA, and was tested for its control effect against X. vesicatoria on red pepper and X. oryzae pv. oryzae on rice. The bacteriocin activity was much higher in the cell extract than in the supernatant. It reached a maximum level at the stationary phase, ws maintained up to 2 months at room temperature and approximately 10 months at $4^{\circ}$. The optimum concentration of glycinecinA for the control in the greenhouse and in the field was 12,800 AU/ml. In this study, the activity of glycinecinA on rice and red pepper leaves continued for 7-8 days, during which the pathogen populations remained at low levels. Bacterial leaf spot of red pepper and bacterial leaf blight of rice were significantly reduced by the bacteriocin treatments. The control efficacy was as high as, or even higher than, the chemical treatment of copper hydroxide. These results suggest that the bacteriocin is a potential control agent for bacterial diseases.

• Research in Plant Disease
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• v.6 no.1
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• pp.6-9
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• 2000

Nine samples of soft rotten roots and blighted leaves of Ficus spp. plants were collected from the vinyl-houses in Taejeon, Seongnam, Suweon and Yangjae in 1988 and pathogenic bactea were isolated from them Results of the studies on morphological, cultural, physiologucal and pathological characteristics indicated that the bacteria from Ficus retusa were Pseudomonas cichorii, from Ficus retusa \`Golden leaf\` and Ficus benjamina were P.viridiflava. These are the first description of bacteria which caused the diseases on Ficus spp. in Korea. We proposed to name the disease of Ficus retusa by P. cichorii as \"bacterial root rot of Ficus retusa\" and Ficus retusa(Golden leaf) and Ficus benjamina by P. viridiflava as \"bacterial leaf blight of Ficus retusa (Golden leaf)\", \"bacterial blight of Ficus benjamina\", respectively.

• Journal of fish pathology
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• v.33 no.1
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• pp.91-95
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• 2020

Fish bacterial diseases have spread and caused serious problem for cultured marine fish in Korea. The important bacterial disease affecting mariculture such as olive flounder (Paralichthys olivaceus) are caused by Edwardsiella tarda, Vibrio scophthalmi and Streptococcus parauberis. For the bacterial disease protection in aquaculture industry, the water treatment is needed in aquaculture system. During the last decades atmospheric pressure non-thermal plasma in contact with liquids have received a lot of attention of environmental and medical application. In this study, we determined the disinfectant effect in seawater and three major fish bacterial disease pathogens by using low frequency plasma treatment. Three fish bacteria (E. tarda, V. schophthalmi, S. parauberis) were not detected within 16 min, 150 min and 270 min of 20 L, 500 L and 1 ton seawater post low frequency plasma treatment, respectively. Three major fish bacterial disease pathogens were not detected within 2 min after the low frequency plasma treatment, suggesting that the low frequency plasma possess disinfectant effectiveness.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.900-908
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• 2016

The effects of algal inoculation on chemical oxygen demand (COD) and total nitrogen (TN) removal, and indigenous bacterial dynamics were investigated in municipal wastewater. Experiments were conducted with municipal wastewater inoculated with either Chlorella vulgaris AG10032, Selenastrum gracile UTEX 325, or Scenedesmus quadricauda AG 10308. C. vulgaris and S. gracile as fast growing algae in municipal wastewater, performed high COD and TN removal in contrast to Sc. quadricauda. The indigenous bacterial dynamics revealed by 16S rRNA gene amplification showed different bacterial shifts in response to different algal inoculations. The dominant bacterial genera of either algal case were characterized as heterotrophic nitrifying bacteria. Our results suggest that selection of indigenous bacteria that symbiotically interact with algal species is important for better performance of wastewater treatment.

• Journal of Food Hygiene and Safety
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• v.10 no.3
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• pp.175-180
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• 1995

The distribution of bacteria in kimbab and its ingredients have been investigated. The total bacterial counts were over 3$\times$106/g(n=30) when the kimbabs were delivered to restaurant and it exceeded the legal level 1$\times$106/g defined by the Code of Food Standard in 1991. The gram-negative coliforms were also detected 1.9$\times$105. In order to study the cause of bacterial contamination in kimbabs, the ingredients used in kimbabs were examined. The bacterial counts were found 104-108/gfor kim (laver), 104-108/g for sausage, 104-106/g for boiled-spinach, 103-107/g for carrot, and 104-106/g for Danmuji, respectively. From these results it could be concluded that the bacterial contamination in Kimbabs was caused mainly by the ingredients such as kim, boiled-spinach, carrot, and sausage. Therefore, this suggested that the sanitary manufacture of kim, the storage at refrigerator temperature of the ingredients for kimbabs, and the proper treatment of equipments should be maintained in order to reduce the bacterial contamination for kimbabs. Furthermore, it should be required to obtain the basal data for establishment of the sanitary standard of kim and kimbab.