• Research in Plant Disease
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• v.24 no.4
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• pp.328-331
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• 2018

A severe disease with leaf spots and necrotic symptoms was observed in cucumber (Cucumis sativus L.) seedlings in April 2018 at a nursery in Kimjae, Korea (35o 47'09.8"N 127o 2'24.3"E). The infected plants initially showed spots on water-soaked cotyledons which, at later stages, enlarged and spread to the leaves, which the lesions becoming dry and chlorotic. The symptomatic samples were collected from cucumber and the isolates were cultured on LB agar. The representative bacterial strain selected for identification showed fluorescent on King's medium B, was potato rot-positive, levan and arginine dihydrolase-negative, oxidase-negative and tobacco hypersensitivity-positive in LOPAT group 2 as determined by LOPAT tests. A pathogenicity test was carried out on a 3-week-old cucumber. After 3 days of inoculation, leaf spots and necrotic symptoms appeared on the cucumber, similar to the originally infected plants. The infecting bacterial strain was identified as Pseudomonas viridiflava, by 16S rDNA sequence analysis. This is the first report of leaf spot diseases on cucumber caused by P. viridiflava.

• Korean Journal of Environmental Biology
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• v.27 no.3
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• pp.272-278
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• 2009

To investigate abundance of soil organisms in the ginseng cultivation, we have selected 6 different cultivated lands in Jinan-gun, Jeollabuk-do. The microarthropods were assessed on the basis of 3,101 individuals collected between April and November 2008. The taxonomic composition and abundance of microarthropods were as follows: Acari 44.9%, Collembola 50.1% and others 5.0%. Density increased at the cast and 4 year point, and the population of microarthropods was high in April and May, but low in July and August. Acari/Collembola ratio was approximately 0.90%. There was no correlation between soil factors and microarthropods. The density of soil actinomyces represented a monthly average $0.3{\sim}0.9{\times}10^6\;cfu\;g^{-1}$, and fungi tended to increase and decrease regularity at each spots, where highest decrease was observed in August and September. The density of bacteria was $1.1{\sim}9.6{\times}10^6\;cfu\;g^{-1}$ in each period and those in June and August were much higher than after August. The distribution of fluorescent Pseudomonas showed regular tendency in early survey periods but did not appear in significant numbers after July.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.319-325
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• 1999

A culture-dependent survey of bacterial community in the soil-root system of red pepper and tomato was conducted by dilution plate count method. The bacterial community within soil was not different from that of rhizoplane. However, the populations of fluorescent, pseudomonads were higher in rhizoplanes than in soils and higher in healthy rhizoplanes than in Phytophthora disease-infested rhizoplanes. The bacterial community of the pepper cropped soil and rhizoplanes was very similar to that of the tomato-cropped soil and rhizoplanes. Among 285 identified bacterial colonies, most colonies were belong to two groups by fatty acid analyses: 52% of the 285 colonies were belong to low G + C gram positive bacteria group. Bacillus spp. and 33% were belong to high G + C gram positive bacteria group. In order to use beneficial microorganisms to agro-ecosystem, these data of field trials should be intensively accumulated.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1284-1289
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• 2007

The Biological Activated Carbon (BAC) process in the water treatments represents a kind of biofiltration process which capabilities of bacteria to remove organic matters are maximized. It enables to eliminate organic matters and effectively reduce microbial regrowth potentials. As attached bacteria employ natural organic matter as a substrate, they are significantly dependent on indigenous microorganisms. In this study, characteristics of bacterial community by culturable and unculturable Methods have been conducted in a pilot plant using SAC in water treatment process at the downstream of the Nakdong River. Based on the results, HPC and bacterial- production for coal-based activated carbon material were $1.20{\sim}56.2{\times}l0^7$ cfu/g and $1.2{\sim}3.7\;mgC/m^{3}h$, respectively, in the SAC process. The highest level of attached bacteria biomass and organic carbon removal efficiency was found in the coal-based activated carbon. The genera Pseudomonas, Flavobacterium, Alcaligenes, Acilzetobacter, and Spingomonas were identified for each activated carbon material. Pseudomonas vesicularis was the dominant species in the coconut- and coal-based materials, where as Pseudomonas cepacia was the dominant species in the wood-based material. The Scanning Electron Microscope (SEM) observation of the activated carbon surface also found the widespread distribution of rod form and coccus. The community of attached bacteria was investigated by performing Fluorescent in situ hybridization (FISH) analysis. a group was dominant in coal, wood and coccunt-based materials, ${\alpha},\;{\beta}\;and\;{\gamma}$ group ranged from 27.0 ${\sim}$ 43.0%, 7.1 ${\sim}$ 22.0%, 11.3 ${\sim}$ 28.6%, respectively. These results suggest that a group bacterial community appears to be regulated removal efficiency of organic material in water treatment process.

• The Plant Pathology Journal
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• v.25 no.2
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• pp.136-141
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• 2009

Marking biocontrol bacteria is an essential step to monitor bacterial behavior in natural environments before application in agricultural ecosystem. In this study, we presented the simple green fluorescent protein (GFP) reporter system driven by the promoter active in Bacillus species for tagging of the biocontrol bacteria. A constitutive promoter P43 from Bacillus subtilis was fused to an enhanced promoterless gfp gene by overlap extension PCR. The GFP expression was demonstrated by the high fluorescence intensity detected in B. subtilis and Escherichia coli transformed with the P43-gfp fusion construct, respectively. The GFP reporter system was further investigated in two bacterial biocontrol strains B. licheniformis and Pseudomonas fluorescens. When the reconstructed plasmid pWH34G was introduced into B. licheniformis, GFP level measured with the fluorescence intensity in B. licheniformis was almost equivalent to that in B. subtilis. However, GFP expression level was extremely low in other biocontrol bacteria P. fluorescens by transposon based stable insertion of the P43-gfp construct into the bacterial chromosome. This study provides information regarding to the efficient biomarker P43-gfp fusion construct for bio-control Bacillus species.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.287-294
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• 1995

This study demonstrates the influence of environmental conditions, other than iron, on pyoverdin production by fluorescent Pseudomosonas. In slightly acidic pH conditions(pH 6), cell yield was reduced while the siderophore production per cell yield was increased. The optimum temperatures for the siderophore production and cell yield was $19^{\circ}C$ and $28^{\circ}C$ for 7NSK2 and $12^{\circ}C$ and $19^{\circ}C$ for ANP15. The carbon and nitrogen balance showed that at low C : N ratio of the growth medium (higher nitrogen concentration), both cell yield and siderophore production was reduced. Use of different carbon sources revealed that citrate as a carbon source facilitated iron uptake and resulted in a significant reduction in siderophore production. However, at the late exponential phase, the iron content in the cell biomass was not significantly different from those grown in glucose or succinate. From these results it can be suggested that the environmental factors other than iron may also influence siderophore production by fluorescent pseudomonas.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.292-301
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• 2000

To make a better use of the beneficial bacterial inoculants in the agricultural practice, dry forms of bacterial fertilizer or pesticides are prepared with carrier materials. During the drying process of bacterial inoculant, most of the cells face a severe osmotic pressure and dehydration, and die off. Our study describes the effect of osmoprotectants such as trigonelline and trehalose on the survival of bacterial cells in high salt concentration and drying conditions. A fluorescent Pseudomonas, strain SSL3, used in this study, could grow in high salt concentration of upto 5% but the cells could not overcome the growth retardation at over 7% of salt concentration. The addition of trigonelline, even on small amount, in liquid medium containing 4% NaCl was detrimental to the cell. However, the addition of trehalose of upto 10 mM to the liquid medium containing 4% NaCl, enhanced cell growth. The cell growth was retarded when 150mM trehalose was added to the medium. Upon dry formulation of cells, trehalose was added. And the dry cells were inoculated into the soil to determine the effect of osmoprotectants on the survival of the cells. The survival of the cells, both in wet or dry soil, was improved by the addition of trehalose during the dry cell formulation. The positive effect of trehalose on the cell survival at $-20^{\circ}C$ and $-70^{\circ}C$ was oven more pronounced. The FTIR (Fourier transformation infra-red) spectroscopic analysis showed that the change of the 2nd amide group was reduced by adding trehalose to the medium containing 4% NaCl. These results suggest that trehalose can protect the cell membrane from dryness or high concentration of salt, thereby diminishing the sudden change of the protein structure of the cell membrane and, as a consequence, improving the cell survival.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.53-59
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• 1990

The antagonistic fluorescent pseudomonas, which was isolated from continuous cropping rhizosphere of pepper and cucumber, was identified as Pseudomonas fluorescens (P.f.). For further study, transformant was derived from the isolated P.f. after spontaneous mutation to give antibiotic resistance to nalidixic acid and rifampicin as marked strain. Both P.f. and transformant strains were used for this study and the results obtained were summarized as follows. 1. One of the most effective antagonistic strain, KR164, was selected against F. solani, F. oxysporum, R. solani and this strain was identified and classified as Pseudomonas fluorescens biotype IV. 2. Transformant, KR1641, was derived from strain KR164 and both strains had the same biological and biochemical characteristics. 3, Mycelial lysis and abnormal mycelia of plant pathogenic fungi were microscopically observed after simultaneous culture of fungus and given bacterial strain. 4. The length of chinese cabbage to the autolyzed became longer with given bacterial strain in dark culture. 5. Percentage of germination, number of leaves, length of height, and length of root in chinese cabbage in pot experiment were improved by inoculation of given bacterial strain. 6. The number of given bacterial strain kept generally stable until 34 days after inoculation of itself in pot experiment. Inoculation of given bacterial strain did affect the number of plant disease fungi to be decreased but did not affect the number of other bacteria, Bacillus, in pot experiment.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.480-491
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• 2017

Fluorescent pseudomonads have been isolated from halophytes, mesophytes, and xerophytes of Pakistan. Among these, eight isolates, GS-1, GS-3, GS-4, GS-6, GS-7, FS-2 (cactus), ARS-38 (cotton), and RP-4 (para grass), showed antifungal activity and were selected for detailed study. Based on biochemical tests and 16S rRNA gene sequences, these were identified as strains of P. chlororaphis subsp. chlororaphis and aurantiaca. Secondary metabolites of these strains were analyzed by LC-MS. Phenazine-1-carboxylic acid (PCA), 2-hydroxy-phenazine, Cyclic Lipopeptide (white line-inducing principle (WLIP)), and lahorenoic acid A were detected in variable amounts in these strains. P. aurantiaca PB-St2 was used as a reference as it is known for the production of these compounds. The phzO and PCA genes were amplified to assure that production of these compounds is not an artifact. Indole acetic acid production was confirmed and quantified by HPLC. HCN and siderophore production by all strains was observed by plate assays. These strains did not solubilize phosphate, but five strains were positive for zinc solubilization. Wheat seedlings were inoculated with these strains to observe their effect on plant growth. P. aurantiaca strains PB-St2 and GS-6 and P. chlororaphis RP-4 significantly increased both root and shoot dry weights, as compared with uninoculated plants. However, P. aurantiaca strains FS-2 and ARS-38 significantly increased root and shoot dry weights, respectively. All strains except PB-St2 and ARS-38 significantly increased the root length. This is the first report of the isolation of P. aurantiaca from cotton and cactus, P. chlororaphis from para grass, WLIP and lahorenoic acid A production by P. chlororaphis, and zinc solubilization by P. chlororaphis and P. aurantiaca.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.43-53
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• 2017

In this study, we analyzed the densities and taxonomic characteristics of various microorganisms that play important roles in Agaricus bisporus culture medium composting, and examined changes in the levels of decomposition-related enzymes secreted by these microorganisms. Various microorganisms such as thermophilic bacteria, actinomycetes, fluorescent Pseudomonas spp., and filamentous bacteria are closely associated with culture medium composts of Agaricus bisporus. The population densities of microorganisms change, and harmful bacteria disappear during thermophilic composting. Psychrobacter sp., Pseudomonas sp., Bacillus sp., and Pseudoxanthomonas sp. accounted for the highest proportion of bacteria in the culture media during outdoor composting, whereas Bacillus sp. and Psychrobacillus sp. were dominant after pasteurization. Cellulose and hemicellulose enzymes of the microorganisms were important at an early stage of rice straw composting and after decomposition of carbon sources, respectively. Microorganisms that secreted these enzymes were present in the second and third turning stage of composting.