• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.194-202
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• 2003

To isolate alga-lytic bacteria, a number of samples were collected from Lake of Sukchon and Pal'tang reservoir where cyanobacteria blooming occurred. HY0210-AK1, which exhibited high alga-lytic activity, was isolated using Anabaena cylindrica lawn. The morphological and biochemical characteristics of the isolate HY0210-AK1 were very similar to that of the genus Rhizobium. Taxonomic identification including 16S rDNA base sequencing and phylogenetic analysis indicated that the isolate Hy0210-AK1 had a 99.1% homology in its 16S rDNA babe sequence with Sphingobium herbicidovorans. A. cylindrica NIES-19 was susceptible to the alga-lytic bacterial attack. The growth-inhibiting offset of the bacterium was not different on A. cylindrica NIES-19 when Sphingobium herbicidovorans HY0210-AK1 was in the lag, exponential, and stationary growth phase, although the alga-Iytic effect of S. herbici-dovorans HY0210-AK1 that in stationary growth phase was somewhat pronounced at the first time of inoculation. When S. herbicidovorans HY0210-AK1 was inoculated was inoculated with $1\times 10^{8}$ CFU $ml^{-1}$ together with A cylindrica NIES-19, the bacterium proliferated and caused algal lysis. A. cylindrica NIES-19 died when S. herbicidovorans HY0210 AKl was added to the algal culture but not when duly the filtrates from the bacterial culture was added. This suggests that extracellular substances are not responsible for inhibition of A. cylindrica NIES-19 and that algal Iysis largely attributed to direct interaction between S. herbicidovorans HY0210-AK1 and A. cylindrica NIES-19. The alga-lytic bacterium HY0210-AK1 caused cell lysis and death of three strain of Micro-cystis aeruginosa, but revealed no alga-Iytic effects on the Stephanodiscus hantzschii.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.187-197
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• 1987

Bacteria and fungi antagonistic to Fusarium oxysporum f. sp. cucumerinum Owen were effectively isolated with each of modified Triple Layer Agar (TLA) technique from rhizosphere soil where cucumber had been grown healthily in plastic film house. Three predominant bacterial isolates selected were identified as Pseudomonas fluorescens, and P. putida, Serratia sp. and three fungal isolates were Gliocladium sp. Trichoderma harzianum, and T. viride. Antagonistic bacteria inhibited $26-45\%$ of germination and $41-56\%$ of germ tube elongation of microconidia of F. oxysporum f. sp. cucumerinum on Water Agar (WA). P. fluorescens was the strongest inhibitor. Several my co parasitisms were observed on dual culture of WA between antagonistic fungi and F. oxysporum f. sp. cucumerinum such as coiling, penetration, overgrowing, and lysis. Mycelial lysis of the pathogen was the most severe at pH 4.6, followed by 3.6, 5.6 and 6.6 of the medium in decreasing order. At pH 6.6, mycelia of the pathogen were not conspicuously damaged, however, the antagonistic fungi formed abundant chlamydospores especially Gliocladium sp. T. harzianum revealed the most excellent antagonism in vitro.

• The Journal of Korean Society of Virology
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• v.26 no.1
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• pp.9-22
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• 1996

Respiratory Syncytial virus (RSV) is an important cause of acute lower respiratory tract infections in human, with infants and young children being particularly susceptible. In the temperate zones, sharp annual outbreaks of RSV occur during the colder months, in both the northern and the southern hemisphere. RSV is unusual in that it can repeatedly reinfect individuals throughout life and infect babies in the presence of maternal antibody. RSV isolates can be divided into two subgroups, A and B, on the basis of their reactions with monoclonal antibodies, and the two subgroups are also distinct at the nucleotide sequence level. The specific diagnosis of RSV infection was best made by isolation of virus in tissue culture, identification of viral antigen, or by specific serologic procedures. Recently, rapid detection of RSV and analysis of RSV strain variation became possible by development of methods of reverse transcription and polymerase chain reaction amplification. In this study, to determine the genetic diversity of RSV found in Korea, 173 bp and 164 bp spanning selected regions of the RSV F and SH genes were enzymatically amplified and sequenced, respectively. Eight for F gene and three for SH gene were detected in 66 nasopharyngeal swap samples tested. Two major antigenic subgroups, A and B were confirmed from Korean samples (seven for subgroup A and one for subgroup B). At the nucleotide level of the F gene region, Korean subgroup A strains showed 95-99% homologies compared to the prototype A2 strain of subgroup A and 93-100% homologies among Korean subgroup A themselves. For the SH gene region, Korean subgroup A strain showed 97.5% homology compared to the prototype A2 strain of subgroup A, and Korean subgroup B strain showed 97% homology compared to the prototype 18537 strain of subgroup B. Most of base changes were transition and occured in codon position 3, which resulted in amino acid conservation. Using the maximum parsimony method, phylogenetic analysis indicated that Korean RSV strains formed a group with other RSV strains isolated from the United States, Canada, the Great Britain and Australia.

• Parasites, Hosts and Diseases
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• v.29 no.2
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• pp.139-148
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• 1991

Cryptosporidium, a coccidian protozoa, commonly causes a self-limiting diarrheal illness in humans and animals. Fecal samples from various animals in Chonbuk district were observed using Sheather's aoatation technique, Kinyoun's modified acid-fast staining, and osmic acid pre-fixed Giemsa staining. The oocysts were detected in 74 cages(29.6%) out of 250 cages of mature mice, 26 (13.3%) out of 195 mature house rats, 75 (15.0%) out of 4-week-old 500 fowls, 98(19.9%) out of 6 to 8-month-old 500 pigs, and 111(22,2%) out of 2 to 5-year-old 500 dairy cattle, respectively. The degree of prevalence was slight in general, but actual prevalence was higher than infection rate because the detection rates were higher in repeated-preparation examinations in comparison to the first examination. Meanwhile, large and small types of oocysts were detected from mice, house rats, pigs, and cattle, and midium type from fowls.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.261-265
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• 2000

To develope the enhanced bacterial strains capable of biodegradation for various chlorinated aromatic compounds, 100 bacterial strains were isolated from soil samples of suburbs of Taejon, Cheongju, and Jeonju by the enrichment culture. These strains can degrade pentachlorophenol (PCP) which is a kind of wood preservatives. Nineteen strains of the isolates were selected by fast colony-forming rate on solid minimal media containing PCP as an only source of carbon and energy. These strains were identified to genus level. Fifteen strains were identified as Pseudomonas, 1 strain as Acinetobacter and 3 strains were not. Genus Alcaligenes strains were not found among them. Pseudomonas sp. MU135. MU139, MU163 and MU 184 were able to degrade for 4 kinds of chlorinated compounds, PCP, 2,4-D, MCPA and 3CB. Pseudomonas sp. If was observed that MU139 exhibits the highest degradability in liquid minimal media at 72 hours after inoculation. Pseudomoans sp. MU147, MU177, MU184 and MU192 also degraded the compounds at higher rates. As the results, Pseudomonas sp. MU139 and unidentified strain MU184 had biodegrability for broad range of chlorinated compounds and higher rates of degradation for PCP.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.211-221
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• 2012

The fourth leaves (younger leaves) amongst extended 4-upper leaves in 18 squash cultivar were the highest tolerance to the paraquat application, followed by third, the second, and the first leaves (older leaves). The forth leaves in Joongangaehobak showed more than three times higher tolerance to the paraquat application than did the first leaves. When the combining of water extract from the fourth leaves with paraquat were applied to the leaves and stems of maize, the paraquat phytotoxicity in maize was reduced compared to the paraquat application alone. Therefore, this study continued to investigate if the phytotoxicity inhibitor exist in the fourth leaves. The water extract in the fourth leaves were isolated by silica gel column chromatography, Sephadex LH-20 column chromatography, TLC, and HPLC, and the substance in the extract was speculated as a malic acid by identifying through NMR. The mixture malic acid and paraquat were applied to the maize to verify the application effect of malic acid on paraquat toxicity. The 100 ${\mu}M$ of paraquat application alone showed 62% of paraquat toxicity to the corn leaves, while the combined application of 100 ${\mu}M$ paraquat with malic acid at 0.1, 0.3, 0.5, and 1.0% did not show the symptom.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.741-755
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• 1999

As a material of metal-ceramic prosthesis, nickel as a form of Ni-Cr alloy has been used for many dental prostheses in many cases. However, several problems in use of the alloy have been revealed (ex : tissue stimulation, skin allergy, hypersensitivity, cytotoxicity and carcinogenecity). Little is known about nickel with respect to the relationship between Ni-prosthesis and gaining of Ni-resistance in oral microorganisms. The present study was undertaken to check wheather use of Ni-prosthesis leads to occurrence of Ni-resistant microorganisms. So this study may suggest the possible relationships between the oral microorganisms and nickel-resistance in oral environment. Bacteria were isolated from the gingival crevicular fluid on the pateints wearing Ni-Cr prosthesis. The isolated bacteria were tested for their Ni-resistance in nickel containing media at different concentration from 3mM to 110mM. E. coli HB101 was used as control. The Ni-resistant bacteria were isolated and biochemically identified. The Ni-resistant bacteria were tested several bio-chemical, molecular-biological tests. Performed tests were ; measuring the growth curve, antibiotic test, growth ability test in liquid media, isolation of the chromosome and plasmid, digestion of DNA by restriction enzyme, electrophoresis of chromosome and plasmid DNA, identification of Ni-resistant genes by the DNA hybridization. The results were as follows: 1) The bacteria isolated from gingival crevicular fluid on the patients wearing Ni-Cr alloy pros-thesis showed nickel-resistance. 2) The isolated microorganisms grew at nickel containing media of high concentrations (60mM-110mM). 3) Based on the biochemical tests, the isolated microorganisms were identified as Enterococcus faecalis(13 cases), Klebsiella pneumoniae(1 case) and Enterobacter gergeviae(1 case). 4) Enterococcus faecalis expressed not only nickel resistance but also the multi-drug resistance to several antibiotics ; chloramphenicol, kanamicin, streptomycin, lincomycin, clindamycin. However, all strain showed the sensitivity against the tetracycline. 5) DNA hybridization result suggest that there is no homology between the previousely known gene of nickel resistance in Klebsiella pneumoniae and chromosomal DNA of Enterococcus faecalis.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.4
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• pp.292-297
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• 2014

DNA extraction is a prerequisite for the identification of pathogens in clinical samples. Commercial DNA extraction kits generally involve time-consuming and laborious multi-step procedures. In the present study, our modified DNA isolation method for saliva samples allows for the quick detection of pathogens associated with dental caries or periodontitis by PCR within 1 h. To release DNA from the bacteria, 1 min of boiling was adequate, and the resulting isolated DNA can be used many times and is suitable for long term storage of at least 13 months at $4^{\circ}C$, and even longer at $-20^{\circ}C$. In conclusion, our modified DNA extraction method is simple, rapid, and cost-effective, and suitable for preparing DNA from clinical samples for PCR for the rapid detection of oral pathogens from saliva.

• The Korean Journal of Mycology
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• v.26 no.4 s.87
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• pp.531-537
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• 1998

Forest green mold incidence rate, extent of damage according to the inoculation periods, and its cultural characteristics were observed in the automatic cultural system of the winter mushroom, Flammulina velutipes. The incidence rate of the forest green mold was 7.7% in early cultivation stage and slowly increased to 14.9% in harvest stage. When the forest green mold was inoculated at cultural period, the rate was recorded at 100%, but the extent of the damage increased up to 40% (+++). There was also 100% incidence rate at early pinheading time, whereas the yield of mushroom decreased to ++ $(10{\sim}39%)$. The rate of forest green mold was greatly decreased to 34.4% at 10 days after pinheading, and its damage extent was also below 10%. A pathogen to infect the winter mushroom was identified as Trichoderma pseudokoningii. It's optimum temperature for mycelial growth is $25^{\circ}C$, and it grew 2.6 times faster than that of F. velutipes. The mycelial color of T. pseudokoningii was pale yellow or olivaceous in shades on PDA medium. Phialospore was one celled, and ellipsodal or obovoid, smooth walled, and measured $1.3{\sim}3.0{\times}1.0{\sim}2.5\;{\mu}m$. It aggregated in small heads at the tips of the phialides. The phialides were $3.2{\sim}9.2{\times}2.0{\sim}5.5\;{\mu}m$ and were of bowling pin type, solitary and alternate or more irregularly disposed at the conidiophore apex, T. pseudokoningii depressed the F. velutipes growth at the crossing cultivation when they were simultaneously. FV 4-1 (F. velutipes) cultivar was less depressed by T. pseudokoningii, but had a lower cross growth rate than the other four cultivars.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.193-199
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• 2009

A bacterium producing the halotolerant extracellular protease was isolated from squid jeotgal, and was identified as Bacillus sp. SJ-10 based on morphological, physiological and biochemical characteristics, as well as phylogenetic analysis using 16S rRNA gene sequence. The strain grew at $20^{\circ}C\sim55^{\circ}C$, pH 5~8, and 0%~14% NaCl and optimal growth conditions were $35{\pm}5^{\circ}C$, pH 7, and 5% NaCl. The major cellular fatty acids were anteiso-$C_{15:0}$, anteiso-$C_{17:0}$, and $C_{16:0}$ DNA G+C content was 50.58 mol% and menaquinone consisted of MK-7 Phylogenic analysis based on the 16S rRNA gene sequence indicated that SJ-10T belongs to the genus Bacillus. About 40 kDa of the salt-tolerant protease was purified by 40% ammonium sulfate saturation and Mono Q column chromatography. The optimal activity of the protease was pH 8 and stable at pH 5~10. The optimum temperature and NaCl concentration were $35{\pm}5^{\circ}C$ and $5{\pm}1%$, respectively.