• Korean Journal of Microbiology
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• v.40 no.4
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• pp.342-347
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• 2004

A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens Makino in Korea. Based on physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bac­terial strain was identified as Pseudomonas aurantiaca. The bacteria also inhibited mycelial growth of several plant fungal pathogens such as Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani on PDA and 0.1 TSA media. The antifungal activity was found from the culture filtrate of this isolate and the active compound was quantitatively bound to XAD adsorption resin. The antibiotic compound was purified and identified as phenazine-l-carboxylic acid on the basis of combined spectral and chemical analyses data. This is the first report on the production of phenazine-l-carboxylic acid by Pseudomonas aurantiaca.

• Tuberculosis and Respiratory Diseases
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• v.42 no.5
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• pp.646-653
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• 1995

Background: The confirmative diagnosis of pulmonary tuberculosis(Tb) can be made by the isolation of Mycobacterium Tuberculosis(MTb) in the culture of the sputum, respiratory secretions or tissues of the patients, but positive result could not always be obtained in pulmonary Tb cases. Although there are many indirect ways of the diagnosis of Tb, clinicians still experience the difficulty in the diagnosis of Tb because each method has its own limitation. Therefore development of a new diagnostic tool is clinically urgent. It was reported that silica cause some lysosomal enzymes to be released from macrophages in vitro and one of these enzymes is elevated in workers exposed to silica dust and in silicotic subjects. In pulmonary Tb, alveolar macrophages are known to be activated after ingestion of MTb. Activated macrophages can kill MTb through oxygen free radical species and digestive enzymes of lysosome. But if macrophages allow the bacilli to grow intracellularly, the macrophages will die finally and local lesion will enlarge. Then it is assumed that the lysosomal enzymes would be released from the dead macrophages. The goal of this investigation was to determine if there are differences in the plasma activities of lysosomal enzymes, ($\beta$-glucuronidase(GLU) and $\beta$-N-acetyl glucosaminidase(NAG), among the groups of active and inactive pulmonary Tb and healthy control, and to see if there is any possibility that the plasma activity of GLU and NAG can be used as diagnostic indicies of active pulmonary Tb. Methods: The plasma were obtained from 20 patients with bacteriologically proven active pulmonary Tb, 15 persons with inactive Tb and 20 normal controls. In 10 patients with active pulmonary Tb, serial samples after 2 months of anti-Tb medications were obtained. Plasma GLU and NAG activities were measured by the fluorometric methods using 4-methylumbelliferyl substrates. All data are expressed as the mean $\pm$ the standard error of the mean. Results: The activites of GLU and NAG in plasma of the patients with active Tb were $21.52{\pm}3.01$ and $325.4{\pm}23.37$(nmol product/h/ml of plasma), respectively. Those of inactive pulmonary Tb were $24.87{\pm}3.78$, $362.36{\pm}33.92$ and those of healthy control were $25.45{\pm}4.05$, $324.44{\pm}28.66$(nmol product/h/ml of plasma), respectively. There were no significant differences in the plasma activities of both enzymes among 3 groups. The plasma activities of GLU at 2 months after anti-Tb medications were increased($42.18{\pm}5.94$ nmol product/h/ml of plasma) in the patients with active pulmonary Tb compared with that at the diagnosis of Tb(P-value <0.05). Conclusion: The results of the present investigation suggest that the measurement of the plasma activities of GLU and NAG in the patients with active pulmonary Tb could not be a useful method for the diagnosis of active Tb. Further investigation is necessary to define the reasons why the plasma activities of the GLU was increased in the patients with active pulmonary Tb after Tb therapy.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.543-552
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• 1995

This study was undertaken to investigate the eftects of Cd administered ad libitum for 6 weeks on the cellular immune responses of Balb/c mice. The results were summarized as follows; 1. The mice fed 25, 50 and 100ppm Cd drank as much as control, but the mice fed 200ppm Cd drank significantly less water after Cd exposure than did control. Increasing rates of body weight of Cd-fed mice for 6 weeks were as this, control group 27.0%, Cd administered groups(25, 50, 100 and 200ppm) 28.54%, 28.31%, 20.49% and 18.04%, respectively. 2. Absolute spleen to body weight(mg/g) of control, 25, 50, 100 and 200ppm Cd administered groups were $4.34{\pm}0.23$, $4.20{\pm}0.54$, $4.80{\pm}0.87$, $4.25{\pm}0.32$ and $4.40{\pm}0.32$, respectively. Splenic cellularity(${\times}10^7$) of control was $24.29{\pm}5.98$ but increased to $27.72{\pm}5.48$, $32.96{\pm}8.44$, $28.32{\pm}8.76$ and $29.64{\pm}4.08$ in 25, 50, 100 and 200ppm Cd-fed groups, respectively. 3. Total $CD_4{^+}$ cells(${\times}10^7$) of control, 25, 50, 100 and 200ppm Cd-fed groups were $9.15{\pm}2.24$, $10.40{\pm}2.04$, $12.04{\pm}3.08$, $10.20{\pm}3.16$ and $10.80{\pm}1.48$, respectively and total $CD_8{^+}$ cells(${\times}10^7$) of these groups were $2.32{\pm}0.56$, $2.54{\pm}0.27$, $3.12{\pm}0.80$, $2.25{\pm}0.70$ and $2.24{\pm}0.28$, in order. On the other hand, $CD_4{^+}/CD_8{^+}$ ratios in total cells were increased significantly except for 50ppm Cd-fed group($3.88{\pm}0.01$). And that of control was $3.97{\pm}0.02$, but those of 25, 100 and 200ppm were $4.35{\pm}0.01$, $4.54{\pm}0.03$ and $4.81{\pm}0.03$. 4. Phagocytosis rates of peritoneal macrophages were increased significantly in 25 and 50ppm Cd groups($36.34{\pm}9.45$ and $37.15{\pm}9.22$, respectively), but 100 and 200ppm groups showed similar rates($18.20{\pm}3.04$ and $19.48{\pm}3.22$ respectively) to that of control($21.43{\pm}3.62$). 5. In mitogen-induced splenocyte proliferation, various concentraions of $CdCl_2(10^{-4}-10^{-7}M)$ were added to mitogen-stimulated culture in vitro. Splenocyte proliferation induced by LPS was decreased dose dependently, but proliferation by Con-A was increased slightly in concentrations of $10^{-7}-10^{-6}M$. 6. Significant cytotoxicity of splenocytes with $CdCl_2$ were shown at $10^{-4}M$ treated group, especially at 24 hrs. From these results, it could be concluded that Cd might modulate the immune responses by modifying a distribution of T cell subpopulations.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.283-316
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• 1977

In an attempt to obtain a basic information to develop an effective integrated system of controlling sheath blight of rice in Korea, the transition of this disease, the variation of cultural characters and pathogenicity of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. Rice sheath blight which has been minor disease in the past was widely spread, especially since 1971. This disease has promptly spread all over the country and infected 65.2% of total rice growing area in 1976. Various factors are considered to be related to such transition of this disease. Above all, increace of application of nitrogenous fertilizer, early season and earlier cultivation of rice, introduction of more susceptible "Tongil" varieties etc. must be important factors influencing the outbreak of this disease. 2. Great variations in cultural characteristics-such as mycelial growth rate, color of the medium, amount of the aerial mycelium, shape and color of the sclerotia- and in the pathogenicity of isolates of the pathogen, Thanatephorus cucumeris Dank were observed. The optimum temperature for mycelial growth also varied with isolates, from $25^{\circ}C$ to $30^{\circ}C$. There were not necessarily any correlation between curtural characteristics and pathogenicity of isolates of Thanatephorus cucumens. 3. Mycelial grow th of isolates of Thanatephorus cucumens on the PDA medium were correlated with the air temperatures of the region where the isolates were collected. The isolates from the regions with high temperature grew well on PDA medium at $35^{\circ}C$ than those from the region with low temperature, on the other hand, the isolates from the regions with the low temperature grew well on the same medium at $12^{\circ}C$ than those from the regions with high temperature. 4. Pectin polygalacturonase (PG) and cellulase (Cx) were most active on the 3rd day after inoculation on the leaves of rice plant with Thanatephorus cucumeris, whereas pectin methylestrase (PE) was most active on the 4th day after inoculation. Relationship between the activities of PE of isolates and the strength of pathogenicity of isolates was obtained, but PG and cellulase activities were not correlated with pathogenicity of isolates. 5. The tolerence of sclerotia from in-vitro culture to low temperature varied with their water content, the dried cultural sclerotia were more tolerent than wet ones, Dried cultural sclerotia maintained almost 100% germinability for 45 days at $-20^{\circ}C$, whereas wet sclerotia lost viability at $-5^{\circ}C$. The germination ratio of the sclerotia after overwintering changed from 18% to 70% according to the water content of the test paddy fields and the ratio was low in wet paddy condition. 6. To investigate the host range of this fungi in and near paddy field, 17 weeds were inoculated with fungi. The lesions of sheath blight disease was obserbed on Sagittaria trifolia L., Echinochloa crusgalli P. Beauv., Monochoria vaginal is Presl, Polygonum Hydropiper L., Eclipta prostrata L., Digitaria sanguinalis Scapoli. 7. When the level of nitrogen applied was doubled over standard level, total nitrogen content in rice sheath increased, ami when silicate was applied, starch content in rice sheath decreased, inducing the rice plants more susceptible to sheath blight disease. Increased dressing of potash ferilizer reduced the incidence of sheat blight disease. 8. The percentage of infected stems in the early period increased more in the narrow hill plot than in the wide hill plot, but in the late period this tendency was inversed; the percentage of infected stems as well as severity in the wide hill plot increased more compared to the narrow hill plot, and the disease severity in the one plant per hill plot was also low. The number of stems in the wide hill plot was more than the number of stems in the narrow hill plot. This indicates that the microclimate, such as the relative humidity, in the narrow hill plot was more favorable for the development of this disease. 9. There was a high negative correlation between the disease severity of varieties to the sheath blight and the maturity of the varieties, that is, the early varieties were more susceptible than the late ones, and much-tillering varieties usually showed more infection than less tillering varieties. 10. No relationship was obtained between the percentage of infected stems in the early period and the severity after heading, whereas a distinct relationship was obtained between former and latter after Aug. 10.