• Korean Journal of Environmental Biology
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• v.25 no.3
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• pp.260-266
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• 2007

A thermophilic bacterium capable of poly (L-lactide)(PLLA) degradation was isolated from cultivating soil in Korea. The isolate was Gram positive rod-shaped bacterium, and was identified as Geobacillus caldoxylosilyticus based on the 16S rDNA sequence analysis. The strain proved to be a new PLLA degrading bacterium which has not been reported in the open literatures yet. The degradation activity of the strain was assessed in a sterilized compost inoculated with the strain under controlled compost condition at $58^{\circ}C$ for 40 days. The strain mineralized 66%, 57%, 41% and 40% of PLLA5000, PLLA11000, PLLA34000 and PLLA256000 whose weight average molecular weights were 5000, 11000, 34000 and 256000, respectively. Incorporation of 0.1% each of gelatin, yeast extract and ammonium sulfate in the compost containing PLLA256000 as a nutritional supplement raised the biodegradation activity by 27%, 13% and 10%, respectively. Increase of the inoculum size from $10^9cfu\;g^{-1}\;to\;10^{10}cfu\;g^{-1}\;and\;10^{11}cfu\;g^{-1}$ also enhanced the biodegradation activity by 14% and 20%, respectively.

• The Plant Pathology Journal
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• v.32 no.2
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• pp.123-135
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• 2016

U.S. cotton production is suffering from the yield loss caused by the reniform nematode (RN), Rotylenchulus reniformis. Management of this devastating pest is of utmost importance because, no upland cotton cultivar exhibits adequate resistance to RN. Nine populations of RN from distinct regions in Alabama and one population from Mississippi were studied and thirteen morphometric features were measured on 20 male and 20 female nematodes from each population. Highly correlated variables (positive) in female and male RN morphometric parameters were observed for body length (L) and distance of vulva from the lip region (V) (r = 0.7) and tail length (TL) and c' (r = 0.8), respectively. The first and second principal components for the female and male populations showed distinct clustering into three groups. These results show pattern of sub-groups within the RN populations in Alabama. A one-way ANOVA on female and male RN populations showed significant differences ($p{\leq}0.05$) among the variables. Multiple sequence alignment (MSA) of 18S rRNA sequences (421) showed lengths of 653 bp. Sites within the aligned sequences were conserved (53%), parsimony-informative (17%), singletons (28%), and indels (2%), respectively. Neighbor-Joining analysis showed intra and inter-nematodal variations within the populations as clone sequences from different nematodes irrespective of the sex of nematode isolate clustered together. Morphologically, the three groups (I, II and III) could not be distinctly associated with the molecular data from the 18S rRNA sequences. The three groups may be identified as being non-geographically contiguous.

• Research in Plant Disease
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• v.20 no.3
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• pp.223-226
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• 2014

Sclerotium rot caused by Sclerotium rolfsii occurred on Cyclamen europaeum grown at the experimental greenhouse of Gyeongsangnam-do Agricultural Research and Extension Services in April 2013. Infected plants showed water-soaked appearance, wilting, and rotting; severely infected plants eventually died. White mycelial mats spread over lesions, and sclerotia were formed on leaves, petioles, and flower stalks near soil line. On the basis of mycological characteristics, ITS rDNA sequence analysis, and pathogenicity to host plants, this fungus was identified as S. rolfsii Saccardo. This is the first report of sclerotium rot on C. europaeum caused by S. rolfsii in Korea.

• Research in Plant Disease
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• v.15 no.2
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• pp.77-82
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• 2009

The roots of grapevine in the field in which the crown gall was occurred severely in Chungbuk province were collected and Agrobacterium spp. were isolated from the roots using the selective media. The selected 13 isolates were identified as A. tumefaciens with fatty acid analysis using MIDI system, nucleotide sequence of 16S rDNA, biochemical characteristics, and PCR with the species-specific primers. A. vitis, a pathogen of crown gall disease of grapevine was not isolated from the roots. All of the isolates did not show pathogenicity on the tomato seedlings and the stem and root of grapevine. Eric-PCR showed that DNA band patterns of the root isolates were a little more similar to A. tumefaciens than A. vitis. However, overall similarity between the root isolates and the pathogenic strains of A. tumefaciens and A. vitis was low by rep-PCR. These results suggest that a pathogen causing crown gall in grapevine in Chungbuk province may transmitted through the seedlings rather than via soil or roots.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.125-135
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• 2013

In agro-ecosystems worldwide, some of the most important and devastating diseases are caused by soil-borne necrotrophic fungal pathogens, against which crop plants generally lack genetic resistance. However, plants have evolved approaches to protect themselves against pathogens by stimulating and supporting specific groups of beneficial microorganisms that have the ability to protect either by direct inhibition of the pathogen or by inducing resistance mechanisms in the plant. One of the best examples of protection of plant roots by antagonistic microbes occurs in soils that are suppressive to take-all disease of wheat. Take-all, caused by Gaeumannomyces graminis var. tritici, is the most economically important root disease of wheat worldwide. Take-all decline (TAD) is the spontaneous decline in incidence and severity of disease after a severe outbreak of take-all during continuous wheat or barley monoculture. TAD occurs worldwide, and in the United States and The Netherlands it results from a build-up of populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing fluorescent Pseudomonas spp. during wheat monoculture. The antibiotic 2,4-DAPG has a broad spectrum of activity and is especially active against the take-all pathogen. Based on genotype analysis by repetitive sequence-based-PCR analysis and restriction fragment length polymorphism of phlD, a key 2,4-DAPG biosynthesis gene, at least 22 genotypes of 2,4-DAPG producing fluorescent Pseudomonas spp. have been described worldwide. In this review, we provide an overview of G. graminis var. tritici, the take-all disease, Pseudomonas biocontrol agents, and mechanism of disease suppression.

• Journal of Sericultural and Entomological Science
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• v.40 no.2
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• pp.126-130
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• 1998

A noninsecticidal strain, Bacillus thuringiensis NTB-88, isolated from Korean soil, had a typical bipyramidal parasporal inclusion and its serotype is identical to B. thuringiensis subspmorrisoni (H8a8b). To elucidate differences between insecticidal and noninsecticidal strains, we compared strain NTB-88 to other toxic B. thuringiensis subsp. morrisoni strains (HD-12 and PG-14). Restriction endonucleases digested plasmid DNA patterns showed that strain NTB-88 was different from lepidopteran-toxic strain, HD-12, but it was similar to dipteran-toxic strain, PG-14. The gene type of strain NTB-88 was different from those of other insecticidal strains, Furthermore, the NH2-terminal amino acid sequence of crystal protein of strain NTB-88 had no relation to those of the previously known $\delta$-endotoxins in other toxic strains as well as HD-12 and PG-14 strains. Therefore, the noninsecticidal crystal protein in strain NTB-88 is novel and its property is different from insecticidal ones.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.45-49
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• 2002

Bradyrhizobium japonicum is a soil bacterium with a unique ability to infect the roots of leguminous plants and establish a nitrogen-fixing symbiosis, which has been used as a microbial manure. In this study, we examined the stress response after pretreatment of cells with cold temperature. When pre-treated with cold temperature ($4^{\circ}C$) for 16 hr, B. japonicum increased the viability in subsequent stress-conditions such as alcohol, $H_2O_2$, heat, and dehydration. For cold adpatation, cultured B. japonicum was exposed to $4^{\circ}C$. Upon subsequent exposure to various conditions, the number of adapted cells pretreated by cold adaptation was 10-1000 fold higher than that of non-adaptated ones. It appeared de novo protein synthesis occurred during adaptation, because a protein synthesis inhibitor, chloramphenicol abolished the increased stress tolerance. By using a degenerate PCR primer set, a csp homolog was amplified from B. japonicum genome and sequenced. The deduced partial amino acid sequence of the putative Csp (Cold shock protein) shares a significant similarity with known Csp proteins of other bacteria.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.286-293
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• 2006

Three hundred thirty two bacterial colonies which were able to degrade crude oil were isolated from soil samples that were contaminated with oil in Daejon area. Among them, one bacterial strain was selected for this study based on its low surface tension ability, and this selected bacterial strain was identified as Pseudomonas sp. G314 through physiological-biochemical tests and analysis of its 16S rRNA sequence. Pseudomonas sp. G314 showed a high resistance to antibiotics such as ampicillin, chloramphenicol, spectinomycin, and streptomycin, and heavy metals such as Li, Cr, and Mn. It was found that the optimal pH and temperature for biosurfactant production of Pseudomonas sp. G314 were pH 7.0 and $30^{\circ}C$, respectively. After seven hours of inoculated, the biosurfactant activity reached the maximum, and surface tension of the culture broth was decreased from 72 to 25 dyne/cm. The crude biosurfactant was obtained from the culture broth by acid precipitation, followed by solvent extraction, evaporation and then freeze drying. The CMC (critical micelle concentration) value of the crude biosurfactant was 20 mg/L.

• Journal of Life Science
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• v.14 no.4
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• pp.582-588
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• 2004

Eighty one bacterial strains of parathion degrading bacteria were isolated from soil samples that were contaminated with pesticide in Daejeon area. Among them, one bacterial strain was finally selected in media containing parathion as the sole source of carbon and energy, and this strain was identified as Pseudomonas rhodesiae H5 through physiological and biochemical tests, and analysis of its 16S rRNA sequence. Pseudomonas rhodesiae H5 was able to utilize various carbohydrates but did not utilize sorbose as sole carbon source. Pseudomonas rhodesiae H5 was resistance to ampicillin, spectinomycin, and mitomycin C but sensitive to kanamycin and chloramphenicol. And this strain showed high resistance up to several milligrams of heavy metals such as $BaCl_2$, LiCl, and $MnSO_4$. Optimal growth condition for temperature and pH of P. rhodesiae H5 was 3$0^{\circ}C$, and pH 7.0, respectively. It can be presumed that P. rhodesiae H5 hydrolyzed an organophosphate bond of parathion, forming p-nitrophenol, and then metabolized via ortho-ring cleavage mechanism.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.90-95
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• 2005

An Actinomycetes producing an anti-VRSA (vancomycin-resistant Staphylococcus aureus) substance was isolated from soil. The cultural, morphological, physiological and phylogenetic analyses of an isolated strain were investigated for identification. Cultural characteristics based on ISP (International Streptomyces Project) were as follows: white aerial mycelium, yellow reverse side, and good growth on various medium. Also, the isolate did not produce the soluble pigment. Morphological characteristics were showed cylindrical spore chain and smooth spore surface by SEM (Scanning Electron Microscope). Physiological characteristics were showed LL-type by DAP isomer analysis and detected glycine, glutamic acid and alanine. A phylogenetic analysis of the 16S rDNA provided a clue that the isolated strain was actually a member of the genus Streptomyces, because the determined sequence exhibited a higher homology with Streptomyces echinatus. The isolate was identified to be a genus of Streptomyces sp.. The optimal culture conditions for the maximum production of anti-VRSA substance by Streptomyces sp. were attained in a culture medium composed of $2.0\%$ (w/v) glucose, and $0.4\%$ (w/v) yeast extract. The anti-VRSA substance was highly produced after 5 days of culture. Optimal pH and temperature conditions for the production of anti-VRSA substance were pH 7.0 and $28^{\circ}C$, respectively.