• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.475-480
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• 2010

Actinomycetes are Gram-positive soil bacteria and one of the most important industrial microorganisms due to superior biosynthetic capabilities of many valuable secondary metabolites as well as production of various valuable bioconversion enzymes. Among them are cytochrome P450 hydroxylase (CYP), which are hemoproteins encoded by a super family of genes, are universally distributed in most of the organisms from all biological kingdoms. Actinomycetes are a rich source of soluble CYP enzymes, which play critical roles in the bioactivation and detoxification of a wide variety of metabolite biosynthesis and xenobiotic transformation. Cyclosporin A (CyA), one of the most commonly-prescribed immunosuppressive drugs, was previously reported to be hydroxylated at the position of 4th N-methyl leucine by a rare actinomycetes called Sebekia benihana, leading to display different biological activity spectrum such as loss of immunosuppressive activities yet retaining hair growth-stimulating side effect. In order to improve this regio-selective CyA hydroxylation in S. benihana, previously-identified several secondary metabolite up-regulatory genes from Streptomyces coelicolor and S. avermitilis were heterologously overexpressed in S. benihana using an $ermE^*$ promoter-containing Streptomyces integrative expression vector. Among tested, SCO4967 encoding a conserved hypothetical protein significantly stimulated region-specific CyA hydroxylation in S. benihana, implying that some common regulatory systems functioning in both biosynthesis and bioconversion of secondary metabolite might be present in different actinomycetes species.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.3
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• pp.339-345
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• 1988

Four actinomycetes which produces extracellular chitinase were isolated from soil and organic matter all over the Chonnam provincial area. The chemical composition, morphological, cultural and physiological properties of isolated strain S-25, S-42, S-172 and S-267 were studied in relation to the toxonomical properties. All of strains contained phospholipids such as phosphatidyl ethanolamine, phosphatidyl inositol and diphosphatidyl glycerol. The components of cell wall in all strains have L, L-DAP, Glutamic acid, Alanine, Glycine and Glucosamine. The surface of spore is smooth and colony is grey in all strains, Based on the results obtained in these experiments all of strains are identified as Streptomyces sp.S-25, Streptomyces sp.S-42, Streptomyces sp.S-l72 and Streptomyces sp. S-267.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.63-69
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• 1998

Twenty seven out of ca. 5,000 actinomycete strains, which were isolated from soil collected throughout the country, showed antibicrobial effects against fungai, Rhizopus stronifer (ATCC 6227a), Rhizoctonia solani (KCCM 11271) and yeast, Candida albicans (ATCC 10231). From these antifungal microorganisms, we further selected seven strains which seemed to produce insecticidal substances with in vivo test, using silkworm, Bombyx mori and beet armyworm, Spodoptera exigua. Morphological and biochemical experiments revealed that three strains out of seven were Streptomyces. Further investigations on the physical and chemical properties of these antifungal and insecticidal substances are now in progress.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.70-76
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• 1992

A field experiment was conducted to find out the influence of cropping systems under rotation of paddy-upland soil on soil microorganisms with specific reference to cations concentration in the soil. The results obtained was summarized as follows. 1. The number of soil bacteria and actinomycetes increased in fallow, continuous cultivation of rice and soybean while the number of fungi decreased. 2. Gram negative bacteria as Pseudomonas spp. and Rhizobium spp. remarkably incerased with increasing Gram positive bacteria of Bacillus subtilis in continuous cultivatio of soybean. 3. The relative population of soil born plant pathogen such as Fusarium spp. Rhizoctionia spp. and Phoma spp. to the total soil fungi was high in cultivation of potato and Chinese cabbage. The ratio of soil plant pathogen to the total soil fungi was high in cultivation of potato with Chinese cabbage. 4. The number of bacteria and actinomycetes was positively correlated with ratio of Ca＋Mg/K in soil while negatively correlated with soil fungi.

• The Plant Pathology Journal
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• v.18 no.1
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• pp.30-35
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• 2002

The hyphal growth and biocontrol efficacy of Trichodemo harzianum in soil may depend on its interactions with biotic components of the soil environment. The effect of soil microbial biomass on growth and biocontrol efficacy of T. hanianum isolate ThzIDl-M3 (green fluorescent protein transformant) was investigated using artificially prepared different levels of soil microbial biomass (153,328, or 517ug biomass carbon per g of dry soil; BC). The hyphal growth of T. harzanum was significantly inhibited in the soil with 328 or 517 $\mu$g BC compared with 153 ug BC. When ThzIDl-M3 was added to the soils as an alginate pellet formulation, the recoverable population of ThzIDl-M3 varied, but the highest population occurred in 517ug BC. Addition of alginate pellets of ThzIDl-M3 to the soils (10 per 50 g) resulted in increased indigenous microbial populations (total fungi, bacterial fluorescent Pseudomonas app., and actinomycetes). Furthermore, colonizing ability of ThzIDl-M3 on sclerotia of Sclerotinia sclerotiorum was significantly reduced in the soil with high revel of BC. These results suggest that increased soil microbial biomass contributes to increased interactions between introduced T. harzianum and soil microorganisms, consequently reducing the biocontrol efficacy of 1T. harzianum.

• Korean Journal of Medicinal Crop Science
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• v.24 no.4
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• pp.294-302
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• 2016

Background: Crop rotation plays an important role in improving soil chemical properties, minimizing the presence of disease pathogens, and assists in neutralizing autotoxic effects associated with allelochemicals. Methods and Results: Five rotation crops of sudan grass, soybean, peanut, sweet potato, and perilla were cultivated for one year with an aim to reduce yield losses caused by repeated cropping of ginseng. In 2-year-old ginseng grown in the same soil as a previous ginseng crop, stem length and leaf area were reduced by 30%, and root weight per plant was reduced by 56%. Crop rotation resulted in a significant decrease in electrical conductivity, $NO_3$, and $P_2O_5$ content of the soil, whereas organic matter, Ca, Mg, Fe, Cu, and Zn content remained-unchanged. Soil K content was increased following crop rotation with sudan grass and peanut only. Rotation with all alternate crops increased subsequent ginseng aerial plant biomass, whereas root weight per plant significantly increased following crop rotation with perilla only. A significant positive correlation was observed between root rot ration and soil K content, and a significant negative correlation was observed between ginseng root yield and the abundance of actinomycetes. Crop rotation affected the soil microbial community by increasing gram negative microbes, the ratio of aerobic microbes, and total microbial biomass whereas decreases were observed in actinomycetes and the ration of saturated fatty acids. Conclusions: In soil exhibiting crop failure following replanting, crop rotation for one year promoted both soil microbial activity and subsequent ginseng aerial plant biomass, but did not ameliorate the occurrence of root rot disease.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.389-394
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• 2003

In order to screen microorganisms producing phopholipase D (PLD) had high transphosphatidylation activity, about 1,000 Actinomycetes strains were isolated from the 63 soil samples, collected over 6 local area in Korea. When the hydrolytic activity in the supernatant was determined, 131 strains produced PLD more than 0.3 U/ml. Among 131 culture broths tested, 23 ones had transphosphatidylation activity higher than 20% and finally one strain (Actinomycetes KF 923), which had highest hydrolytic and transphophadylation activity, was selected. Actinomycetes KF923 showed the highest hydrolytic activity (13 U/ml) and phosphatidylation activity (95%) after 48 h fermentation using the P medium (yeast extract 1%, peptone 1%, glucose 1.5%, glycerol 1%, $CaCo_3$ 0.4%, pH 7.2). PLD was purified from the culture broth of Actinomycetes KF923 and the specific activity of purified PLD was 567 U/mg. The molecular weight of PLD was about 55 kD and the optimum pH and temperature were 6.0 and $60^{\circ}C$, respectively. The stability of PLD toward pH and temperature were high around pH 8.0 and below $40^{\circ}C$. Special metal ions were not necessary to the PLD activity.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.192-198
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• 2001

This study was carried out to investigate the change of chemical properities and, microorganism due to continual cropping and to find the influences to physiological disordered eggplant fruits. Accumulation of soil nutrients seemed to be increased with the plastic film house duration and decreased with soil depth. The longer the period of eggplant cultivation duration, the lower the ratio of bacteria to fungi(B/F) and actinomycetes to the fungi(A/F) in rhizosphere soils. The soil EC and available $P_2O_5$ were significally correlated with the population densities of fungi($r=0.423^{**}$) and actinomycetes($r=0.438^{**}$), respectively. The ratio of split or drupaceous fruit showed tendency to increase with low soil moisture, and that of hypertrophy fruit showed tendency to increase in fields with longer cultivation years and high soil EC. The soil EC significally correlated with the ratio of hypertrophy fruit ($r=0.719^{**}$, Y=0.210X+0.578)and total physiological disordered fruits ($r=0.656^{**}$, Y=0.769X+7.097). And value of soil (Ca+Mg)/K was correlated with the ratio of physiologically disordered fruits($R^2=0.356^{*}$, Y=-1.333Ln(X)+12.26).

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.370-377
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• 1992

A series of field and laboratory experimentes were conducted to find out the effects of kinds of crops residues and the different amount of fertilizer to the microbial interaction, chemical properties, plant growth and their interaction under continous cultivation of hot pepper, soybean, sesame and upland rice. The results obtained were summerized follows : 1. Total number of bacteria and actinomycetes were enhanced by cultivation of upland rice and soybean while no appreciable effects were obtained by the cultivation of hot pepper and sesame. 2. The number of bacteria, actinomycetes and fungi were increased by return of crop residues when the cultivation of hot pepper, soybean, sesame and upland rice. Specially, actinomycetes was remarkably increased by upland rice cultivation. 3. Increased amount of fertilizer were remarkably affected to decrease of number of soil microorganisms. Specially, actinomycetes succession was appearently affects while plant growing time. 4. The number of identified soil bacterial species were obtained high in order of Bacillus sp.>Rhizobium sp.>Agrobacterium sp.>Pseudomonas sp. The number of Gram positive bacteria were superior than that of Gram negative bateria. 5. Interaction between microbial succession and crops cultivation, the number of Bacillus sp. was increased in hot pepper, Rhizobium sp. was in soybean, and sesame, and Agrobacterium sp. were increased in soybean, respectively. 6. Survival and habitate of soil microorganisms were differ with kinds of crop, application of residue and fertilizers. Most high number of Bacillus sp. Rhizobium sp. and Pseudomonas sp. were obtained on the rhizoplane and rhizosphere while Agrobacterium sp. and Fusarium sp. were high in rhizosphere. 7. Factors in relation to change of soil microbial population was obtained high in order of climates>crops>organic>matter>fertilizer.

• Korean Journal of Organic Agriculture
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• v.12 no.3
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• pp.345-352
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• 2004

This study was carried out to investigate the effect of soil-born microorganism, vitabio on growth of leaf lettuce in the vinyl house. Total weights of leaf lettuce treated with vitabio showed difference compared with untreated leaf lettuce. Sugar content was also increased. Mineral contents of leaf lettuce showed no difference between treated with vitabio and untreated with vitabio. Exchange Capacity (EC) and Organic Matter (OM) in chemical properties of soil treated with vitabio showed higher than soil in untreated vitabio. Vitabio treated soil contained much more microorganisms such as Bacteria, Actinomycetes, Hyphomycetes, Bacillus sp. Pseudomonas sp. after harvest.