• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.103-110
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• 2019

The purpose of this study is to investigate the reaction mechanism of soil and bacteria solution by various mixing ratios. For this purpose, in order to understand the reaction mechanisms of microorganisms and weathered granite soil, the tests were carried out under various mixing ratios additives such as soil, bacteria solution, $Ca(OH)_2$ and fixture. The test results from this study are summarized as follows. Firstly, the reaction between the bacteria solution and fixture produced a precipitate called vaterite, a type of silicate and calcium carbonate. Secondly, as a result of SEM analysis, the resulting precipitates generated from the test results using the specimens with various mixing ratios except SW condition and the irregular spherical microscopic shapes were formed in the size of $150{\mu}m$ to $20{\mu}m$. In addition, it can be seen that the bacteria solution and the fixture reacted between the granules to form an adsorbent material layer on the surface, and the microorganisms had a biological solidifying effect when the pores are combined into hard particles. Finally, The XRD analysis of the sediment resulting from the reaction between the microorganism and the deposit control agent confirmed the presence of a type of calcium carbonate ($CaCO_3$) vaterite, which affects soil strength formation, as well as silicate($SiO_2$).

• Korean Journal of Microbiology
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• v.7 no.1
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• pp.29-40
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• 1969

Two kinds of organic materials, powders of Salicornia and Oryza sativa L. wre added as a source of organic matter to the suspensions of saline soils(soil : water = 1:3) to be 4 per cent of dried saline soil grams. And then, the samples were incubated at $28^{\circ}C$ to improve the decomposition of organic materials by soil microflora. Resutls of this experiment are summarized as followings : 1) The pH of soil suspension showed its highest value on the second or third week after the treatments, which were similar to those of the soil microflora. Results of this experiment are summarized as follwings : 1) The pH of soil suspension showed its highest value on the second ot third week after the treatments, which were similar to those of the soil microflora populations. 2) Salinity increased up to the second week and the highest value of it appeared in the samples which were treated with the powder of Salicornia. In general, the salinity of all samples decreased on the third week after the treatment. The fact was assumed the possibilities of desalination from saline soil by the microbial actions. 3) Soil microflora such as bacteria, actinomycetes and fungi, were determined its populations soil microflora is to act as decomposer in soil. Both of the bacteria and actinomycytes population showed in the third weak after the tratment. In general, 30-years old of saline soil contained microbial population much more than those of 5-year old of saline soil. Salicornia powder favored the increase of both the bacteria and fungal population, and Oryza sativa L. seemed to have been a great role in increase of actinomycetes. Especially, fungal population of the untreated soil suspension contained higher microbial populations more than those of the soils treated with both of the organic materials. 4) Sugar contents of soil suspesions decreased remarkably on the first week after the treatments. 5) The amount of nitrate had similar tendency to those of population changes of soil microflora. Total acidity decreased continuously and the amount of potassium showed its highest value on the third week treatment. However, the amount of phosphorus was determined to be insignificant.

• Journal of the Korean Geotechnical Society
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• v.28 no.6
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• pp.53-61
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• 2012

The purpose of this study is to understand the mechanism of cementation of soil induced by bacteria. In order to understand the mechanism of cementation of soft soils treated with bacteria, six types of specimens(Not treated, Normal concentration bacteria treatment, High concentration bacteria treatment, Supernatant high concentration bacteria treatment, Double high concentration bacteria treatment, and 25% Specimen high concentration bacteria treatment) were made. Scanning Electron Microscope (SEM), EDX and X-ray diffraction (XRD) analyses were performed on the soft silt and loose sand specimens. Compared with the normal bacteria concentration treated specimen, a clearer cementation between particles was observed in the 25% specimen high bacteria concentration treated specimen. On the basis of the preliminary results, it appears that microbial cementation can occur in the soft soil.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.21-30
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• 2015

The goal of this study was to identify relationships between the composition of sulfate reducing bacterial assemblages and terminal restriction fragment length polymorphism (T-RFLP) patterns in rice paddy and dry farming soils. Samples of organic farming soils, conventional farming soils, and dry field farming soils were collected in August and November. Analyses of the soil chemical composition revealed similar total nitrogen, total carbon and total inorganic phosphorus levels; however, the moisture content and total carbon were higher than in the other soils in both August and November, respectively. Sulfate reducing bacteria utilizing lactic acid were more widely distributed than those that used acetic acid, and the number of sulfate reducing bacteria in organic farming soil was most abundant. Phylogenetic analysis based on 181 clones revealed that most showed low similarity with cultured sulfate reducing bacteria, but more than 90% similarity with an uncultured sulfate reducing bacteria isolated from the environment. T-RFLP analysis revealed that fragments of 91, 357, 395, and 474 bp were most common, and the community structure of sulfate reducing bacteria changed seasonally.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.2
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• pp.133-142
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• 1998

This study was conducted to investigate the effects of antagonistic bacteria and pathogenic fungi on the growth of tall fescue(Festuca arundinacea Schreb.) in continuous cropping soil(CCS) and non-continuous cropping soil(NCCS). Tall fescue was established by seeding into pots of 11 cm in diameter and 9 cm in depth containing 1 : 1 mixture of soil and vermiculite, and cultivated at pots with antagonistic bacteria and pathogenic fungi in a vinyl house. The bacteria used in this study were Bacillus subtilis and hsants. B. subtilis was isolated and identified kern forage rhizosphere soil and fusants were isolated through cell hsion from B. subtilis and B. thwingiensis. B. subtilis was named as B. subtilis 101 and hsants were named as F-3, F-7 and F-8. In dark culture experiment, tall fescue inoculated with the antagonistic bacteria lived longer than that of control in both CCS and NCCS. However, tall fescue of CCS lived shorter than that of NCCS. Dry weight of tall fescue inoculated with the antagonistic bacteria was higher than that of tall fescue inoculated with pathogenic hngi in both CCS and NCCS(P< 0.05), and the antagonistic bacteria showed positive effects on the growth of tall fescue. However, Dry weight of tall fescue was decreased by the inoculation of the pathogenic b g i in both CCS and NCCS(P< 0.05).

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.331-337
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• 2000

When microorganism is injected into porous medium such as soils, biomass retained in the pore. Bacteria within these microcolonies produced large amounts of exopolysaccharides and formed a plugging biofilm. Soil pore size and shape are varied from the initial condition as a result of biofilm formation, which make hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. Also, pore sand of before and after biofilm formation compared with scanning electron microscopy. Hydraulic conductivity of Sand and Poorly Graded Sand was decreased approximately 1/10∼1/100 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.162-166
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• 2004

This study investigated tile effect of ozonation on indigenous microorganisms distributed in different size fractions of soil aggregates. Soil was ozonated from 0 to 300 minutes. The treated soils were fractionated into 3 groups (small, <53 $\mu$m; medium, 53-500 $\mu$m; and large, 2000-500 $\mu$m) and total heterotrophic bacteria in the soils were enumerated. Cell number decreased rapidly within 120 minute ozonation and showed slow decrease upon longer ozonation. Abundance of total heterotrophic bacteria in each fraction was in the following order regardless of ozonation time: small>medium>large fractions. Difference in microbial abundance among the fractions was smaller as ozonation time increased.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.1
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• pp.1-12
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• 1995

This study was to investigate an effective biological control of forage diseases and provide a basic data and a model in improving variety of antagonistic bacteria, with growth promoting effect on forage, through cell fusion. The results obtained were summarized as follows; 1. The antagonistic himbacterium against soil-borne phathogenic fungi Fusarium oxysporum and Rhizoctonia solani was isolated from continuous cropping himsphere soil of forage, and its biological and physiological characteristics were investigated. This bacterium was identified as Bacillus subrilis and named BS 101. Another strain for cell fusion was Bacillus thur ingiensis ssp. kurstaki HD-I(BT 37669) with insecticidal crystal. 2. The auxotropic mutants of BS 101 and BT 37669 were derived after mutagenesis using N-methyl-N'nitro- Nitrosoguanidine(NTG) to give amino acid requirement marker. n e s e auxotropic mutants of BS 101 and BT 37669 were named BS 1013(his-) and BT 69(asp-), respectively. 3. The best protoplast requirement was obtained using DM 3 medium, containing 5% casamino acid, 1 M $MgCI_2$ and 2% bovine semm albumin, to give Fusant 3, 7 and 8. BT toxin gene was not identified with fusants by Southern blotting. However, SDS-PAGE analysis of strains showed various protein patterns among fusants. 4. From the dark culture experiment, growth of forage in inoculated soil with antagonistic bacteria was delayed than that of non-inoculated soil with antagonistic bacteria in each continuous cropping soil and in each sterilized soil. On the other hand, growth duration of forage was different between continuous cropping soil and sterilized soil. 5. Seed germination of Alfalfa, Italian ryegrass and Orchardgrass were significantly improved by inoculation of antagonistic bacteria(p< 0.05).

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.496-499
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• 2014

The present study investigated variations in soil microbial communities and the chemical properties of forest soils by differing amounts of penetrating sunlight. The soil temperature was significantly higher in higher light-penetrated soils. Higher light-penetrated soils (LP70) showed significantly more fungal communities than the lower light-penetrated soils (LP40 and LP50) (p < 0.05). The $NH_4$-N concentration in LP70 was significantly lower than those of LP40 and LP50, whereas the other chemical properties showed no significant difference among the soils. The cy19:0 to $18:1{\omega}7c$ ratio was significantly lower in LP70 than in LP 40 and LP50 showing the negative correlation of light level with microbial stresses (p < 0.05). The soil microbial communities and the chemical properties that showed positive eigenvector coefficients for PC1 were the fungi to bacteria, fungi, arbuscular mycorrhizal fungi, and Gram-positive bacteria, whereas negative eigenvector coefficients were found for $NH_4$-N, actinomycetes, Gram-negative bacteria, and bacteria. Consequently, the amount of penetrating light was responsible for microbial compositions in the forest soils in correlation with the concentration of $NH_4$-N and soil temperature.

• Korean Journal of Microbiology
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• v.15 no.1
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• pp.42-45
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• 1977

Bdellovibrio sp. is an ectoparasitic bacteria which is predatory and parasitic upon other bacteria. This study was carried out the isolation of Bdellovibrio sp. from several soil smaples and observation of this organisms by means of electron microscope. The results are as follows ; The primary isolated Bdellovibrio sp. from soil is an obligate intracellular rod form parasite and possess a monoflagella.