• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.833-847
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• 2016

Drought stress is a major agricultural limitation to crop productivity worldwide, especially by which leafy vegetables, plant leaves eaten as vegetable, could be more lethal. The study was carried out to know the effect of drought tolerance plant growth promoting bacteria (PGPB) on water stress of kale seedlings. A total of 146 morphologically distinct bacterial colonies were isolated from bulk soil and rhizosphere soil of leafy vegetables and screened for plant growth promoting microbioassay in greenhouse. Out of them the isolate SB19 significantly promoted the growth of kale seedlings in increasement of about 42% of plant height (14.1 cm), 148% of leaf area ($19.0cm^2$) and 138% of shoot fresh weight (1662.5 mg) attained by the bacterially treated plants compared to distilled water treated control (9.9 cm, $7.7cm^2$, 698.8 mg). Shoot water content of SB19 treated kale seedlings (1393.8 mg) was also increased about 152% compared with control (552.5 mg). The SB19 isolated from bulk soil of kale plant in Iksan, Korea, was identified as species of Bacillus based on 16S rRNA gene sequencing analysis. We evaluated the effect of drought tolerance by the Bacillus sp. SB19 on kale seedlings at 7th and 14th days following the onset of the water stress and watering was only at 7th day in the middle of test. In the survey of 7th and 14th day, there were mitigation effect of drought stress in kale seedlings treated with $10^6$ and $10^7cell\;mL^{-1}$ of SB19 compared to distilled water treated control. Especially, there were more effective mitigation of drought damage in kale seedlings treated with $10^7cell\;mL^{-1}$ than $10^6cell\;mL^{-1}$. Further, although drought injury of bacterially treated kale seedlings were not improved at 14th day compared with 7th day, drought injury of $10^7cell\;mL^{-1}$ of SB19 treated kale seedlings were not happen rapidly but developed over a longer period of time than $10^6cell\;mL^{-1}$ of SB19 or control. The diffidence of results might be caused by the concentration of bacterial suspension. This study suggests that beneficial plant-microbe interaction could be a important role of enhancement of water availability and also provide a good method for improving quality of leafy vegetables under water stress conditions.

• Tuberculosis and Respiratory Diseases
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• v.54 no.1
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• pp.80-90
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• 2003

Background : Goblet cell hyperplasia is a critical pathological feature in hypersecretory diseases of the airways. A bacterial infection of the lung is also known to induce inflammatory responses, which can lead to the overproduction of mucus. Recently, mucin synthesis in the airways has been reported to be regulated by neutrophilic inflammation-induced epidermal growth factor receptor (EGFR) expression and activation. In addition, it was reported that migration of the activated neutrophils is dependent on the matrix metalloproteinases (MMPs), especially MMP-9. In this study, bacterial lipopolysaccharide (LPS)-induced goblet cell hyperplasia and mucus hypersecretion by EGFR cascade, resulting from the MMPs-dependent neutrophilic inflammation were investigated in the rat airways. Methods : Pathogen-free Sprague-Dawley rats were studied in vivo. Various concentrations of LPS were instilled into the trachea in $300{\mu}{\ell}$ PBS (LPS group). Sterile PBS ($300{\mu}{\ell}$) was instilled into the trachea of the control animals (control group). The airways were examined on different days after instilling LPS. For an examination of the relationship between the LPS-induced goblet cell hyperplasia and MMPs, the animals were pretreated 3 days prior to the LPS instillation and daily thereafter with the matrix metalloproteinase inhibitor (MMPI; 20 mg/Kg/day of CMT-3; Collagenex Pharmaceuticals, USA). The neutrophilic infiltration was quantified as a number in five high power fields (HPF). The alcian blue/periodic acid-Schiff (AB/PAS) stain were performed for the mucus glycoconjugates and the immunohistochemical stains were performed for MUC5AC, EGFR and MMP-9. Their expressions were quantified by an image analysis program and were expressed by the percentage of the total bronchial epithelial area. Results : The instillation of LPS induced AB/PAS and MUC5AC staining in the airway epithelium in a time- and dose-dependent manner. Treatment with the MMPI prevented the LPS-induced goblet cell hyperplasia significantly. The instillation of LPS into the trachea induced also EGFR expression in the airway epithelium. The control airway epithelium contained few leukocytes, but the intratracheal instillation of LPS resulted in a neutrophilic recruitment. A pretreatment with MMPI prevented neutrophilic recruitment, EGFR expression, and goblet cell hyperplasia in the LPS-instilled airway epithelium. Conclusion : Matrix metalloproteinase is involved in LPS-induced mucus hypersecretion, resulting from a neutrophilic inflammation and EGFR cascade. These results suggest a potential therapeutic role of MMPI in the treatment of mucus hypersecretion that were associated with a bacterial infection of the airways.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.110-115
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• 2007

Electrochemically active bacteria were successfully enriched in an electrochemical cell using a positively poised working electrode. The positively poised working electrode (+0.7 V vs. Ag/AgCl) was used as an electron acceptor for enrichment and growth of electrochemically active bacteria. When activated sludge and synthetic wastewater were fed to the electrochemical cell, a gradual increase in amperometric current was observed. After a period of time in which the amperometric current was stabilized (generally 8 days), linear correlations between the amperometric signals from the electrochemical cell and added BOD (biochemical oxygen demand) concentrations were established. Cyclic voltammetry of the enriched electrode also showed prominent electrochemical activity. When the enriched electrodes were examined with electron microscopy and confocal scanning laser microscopy, a biofilm on the enriched electrode surface and bacterium-like particles were observed. These experimental results indicate that the electrochemical system in this study is a useful tool for the enrichment of an electrochemically active bacterial consortium and could be used as a novel microbial biosensor.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1434-1443
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• 2019

Although chemical oxygen demand (COD) is an important issue for wastewater treatment, COD reduction with microalgae has been less studied compared to nitrogen or phosphorus removal. COD removal is not efficient in conventional wastewater treatment using microalgae, because the algae release organic compounds, thereby finally increasing the COD level. This study focused on enhancing COD removal and meeting the effluent standard for discharge by optimizing sludge inoculation timing, which was an important factor in forming a desirable algae/bacteria consortium for more efficient COD removal and higher biomass productivity. Activated sludge has been added to reduce COD in many studies, but its inoculation was done at the start of cultivation. However, when the sludge was added after 3 days of cultivation, at which point the COD concentration started to increase again, the algal growth and biomass productivity were higher than those of the initial sludge inoculation and control (without sludge). Algal and bacterial cell numbers measured by qPCR were also higher with sludge inoculation at 3 days later. In a semi-continuous cultivation system, a hydraulic retention time of 5 days with sludge inoculation resulted in the highest biomass productivity and N/P removal. This study achieved a further improved COD removal than the conventional microalgal wastewater treatment, by introducing bacteria in activated sludge at optimized timing.

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.36-40
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• 1994

A water sample was taken from a black smoker chimney of a deep-sea hydrothermal vent by using an unmanned submersible "Dolphin 3K". The temperature of the hydrothermal fluid from the black smoker was $276^{\circ}C$. After isolation by repeated serial dilutions, An extremely thermophilic bacterial strain was selected. The strain designated as DT1331, was an anaerobic, non-motile, coccoid shaped bacterium with about 0.5 to $1.0\;\mu\textrm{m}$ in diameter. The strain DT1331 could grow up to $93^{\circ}C$, but the optimum temperature of this strain was $80^{\circ}C$. The growth occurred in the pH range of 4.5 to 8.5 and the optimum pH was 6.0. The strain DT1331 required 1% to 5% NaCl for growth and cell lysis was observed below 1% NaCl concentration. The bacterium could grow on polypeptides such as tryptone, peptone, soytone and on proteins such as casein or gelatin. However, no growth was observed on single amino acids, sugar and organic acids. Hydrogen gas was detected slightly during growth. This bacterium obligately required elemental sulfur and hydrogen sulfide gas was produced during growth.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.207-209
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• 2005

Serum is a potential source of bacterial, mycoplasmal and viral contamination, and it has a possibility of the introduction of serum proteins, prion and pyrogens into the final vaccine product. For porcine Rotavirus vaccine production, it is necessary to develop serum free medium which do not cause those problems. A new serum free medium was developed for porcine Rotavirus vaccine based on DMEM, and the performance of developed serum free medium was evaluated in terms of Vero cell growth and Rotavirus vaccine production. The cell density, gown in serum free medium developed, was similar with that in serum supplemented medium. Also, it was higher than that in other commercially available serum free medium. The productivity of Rotavirus vaccine using serum free medium developed and optimum production strategies will be also discussed.

• Korean Journal Plant Pathology
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• v.10 no.3
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• pp.163-168
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• 1994

Erwinia rhapontici causes soft-rot disease in a number of plants such as rhubarb, onion, hyacinth and garlic. Pectate lyase (Pel) depolymerizes pectin and other polygalacturonates, which is though to play a role in bacterial invasion of plants. Pel activity was not detected in E. rhapontici cultured in a minimal salts medium containing glycerol, polygalacturonate, or citrus pectin as a carbon source. However, when sterilized potato tuber and Chinese cabbage slices were added to minimal salts polygalacturonate (0.5%) medium, E. rhapontici produced pectate lyase enzyme. Also Pel activity was consistently detected from macerated potato tubers, Chinese cabbage leaves, lettuce leaves and celery petioles tissue. Pel in the extract of macerated Chinese cabbage caused by E. rhapontici strain 1, resulted in electrolyte loss, tissue maceration and cell death of potato tuber tissue. These results indicate that E. rhapontici produces pectate lyase only in the presence of non-diffusible plant components, and that this enzyme probably contributes to its pathogenicity.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.26-33
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• 2002

The seven strains, Pseudomonas paucimobilis, Pseudomonas cepacia, Staphylococcus auricularis, Staphylococcus saprophyticus, Acidovorax spp., Acinetobacter calcoaceticus, and Actinobacillus capsulatus were tested with three slimicides. Most of the tested bacteria were inhibited with slimicide K (an isothiazolin based compound), even at its low concentration, except for Actinobacillus capsulatus and Staphylococcus auricularis. Both slimicides B (an organic bromine based compound) and S (aldehydes) also couldn't prevent these two strains even at their highest concentration. Five different sizes of plasmid DNA were isolated from Actinobacillus capsulatus. Staphylococcus auricularis, a gram-positive bacteria, showed the slimy substances around its cell distinctively. The results suggest that two strains, Actinobacillus capsulatus, Staphylococcus auricularis, have presumably developed a resistance to the slimicide, by plasmid DNA or slimy substance. Our findings also suggest that not only gram-negative bacteria, but also gram-positive bacteria should not be neglected

• The Korean Journal of Food And Nutrition
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• v.5 no.2
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• pp.77-83
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• 1992

The optimum conditions and mechanisms for the plasmid-mediated genetic transformation of intact cells of Bacillus brevis Pl76-2, an extracellular protein producing bacterium by electroporation were investigated. It was found that pUB110 Plasmid DNA can be introduced into intact bacterial cells by electroporation. The frequency of transformation by this electroporation system depended upon the initial electric field strength, the capacity of the electric discharge capacitor, growth stage, number of successive pulses and composition of electroporation buffer. It was effective for transformation that cells were harvested, washed and resuspended with HSM [7M HEPES(PH 7.4), 272mM sucrose, 1 mM MgCl2] electroporation buffer when cell growth was attained to 1.2 at OD660. A maximum frequency of transformation of 2.40$\times$104 transformants per$\mu$g plasmid DNA was obtained by two succesive Pulses with an initial electric field strength of 12.5kV/cm and with a capacitance of 7.3uF.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1849-1855
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• 2006

It has been shown that the initial conditions of bacterial cultivation are extremely important for the successful production of hyaluronic acid (HA) by fermentation. We investigated several parameters that affect cell growth rate and the productivity and molecular weight of hyaluronic acid--i.e., agitation speed, aeration rate, culture temperature, pH, and pressure--to determine how to optimize the production of HA by Streptococcus zooepidemicus on an industrial scale. Using a 30-1 jar fermentor under laboratory conditions, we achieved maximum HA productivity and biomass when the agitation speed and aeration rate were increased simultaneously. By shifting the temperature downward from 35$^{\circ}C$ to 32$^{\circ}C$ at key levels of cell growth during the fermentation process, we were able to obtain HA with a molecular weight of $2.8{\times}10^6$ at a productivity of 5.3 g/l. Moreover, we reproduced these optimized conditions successfully in three 30-1 jar fermentors. By reproducing these conditions in a 3-$m^3$ fermentor, we were able to produce HA with a molecular weight of $2.9{\times}10^6$ at a productivity of 5.4 g/l under large-scale conditions.