• Korean Journal of Environmental Biology
• /
• v.35 no.4
• /
• pp.694-705
• /
• 2017

The aim of this study was to isolate and identify marine bacterium with anti-methicillin-resistant Staphylococcus aureus (MRSA) activity, and to purify the anti-MRSA compound, as well as to determine its activity and synergistic effects. Among the marine bacteria isolated in this study, the YJ-1 isolate had the strongest anti-MRSA activity. The YJ-1 isolate was identified on the basis of its biochemical characteristics and an analysis of 16S rRNA gene sequences. The YJ-1 isolate showed over 99.2% homology with Pseudomonas stutzeri, and was designated as a Pseudomonas sp. YJ-1. The optimal culture conditions were $25^{\circ}C$ and initial pH 7.0. For the purification of the anti-MRSA compounds, the YJ-1 was cultured in Pa PES-II medium, and the culture filtrates were extracted by ethyl acetate, hexane, and 80% MeOH. The 80% MeOH fraction was separated by a $C_{18}$ ODS column, silica gel chromatography and a reverse phase HPLC, to yield three anti-MRSA agents, the MR1, MR2, and MR3 compounds. When the MR1 compound of $250{\mu}g\;mL^{-1}$ concentration was applied to the MRSA cells, over 95% of bacterial cells was killed within 48 hr. Compared with vancomycin and ampicillin, the MR1 compound showed significant anti-MRSA activity. In addition, the anti-MRSA activity was increased by dose and time dependent manners. Furthermore, the combination of an MR1 compound with vancomycin produced a more rapid decrease in the MRSA cells than did the MR1 compound alone. Taken together, our results suggest that the Pseudomonas sp. YJ-1 and its anti-MRSA compounds could be employed as a natural antibacterial agent in MRSA infections.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.42 no.4
• /
• pp.229-236
• /
• 2022

This study was conducted to evaluate the efficacy of adding the microbial inoculants to silage for reducing mycotoxins in rice straw silage. When a single agent of L. plantarum and a mixed agent of L. plantarum and S. cerevisiae were added in rice straw silage contaminated mycotoxins, it had an effect on silage fermentation and fiber degradation as well as mycotoxin reduction. Among the mycotoxins, only ochratoxin A and zearalenone were found in the test sample. Ochratoxin A and zearalenone showed a decreasing trend with the addition of silage inoculants compared to the control groups (38.11±2.22 and 633.67±50.30 ㎍/kg), and there was a significant difference at the mixed agents; 27.78±2.28 and 392.72±25.04 ㎍/kg, respectively (p<0.05). The pH was lower in the single agent and the mixed agent compared to the control (p<0.05). The concentration of lactic acid was higher in the single agent (11.73±0.31 mM) than in the control group (8.18±0.93 mM), and the highest concentration was 16.01±0.88 mM in the mixed agent (p<0.05). Acetic acid and propionic acid were found to be significantly lowered with the addition of silage inoculants (p<0.05). Total VFA was also lower at the addition of silage inoculants than the control group (p<0.05). The rumen in situ dry matter degradation of NDF and ADF was maintained at the highest levels of the mixed agent during the culture period, followed by the single agent and the control group at the lowest level. NDF and ADF degradation showed a significant difference at all time points after 12 and 24 hours of culture, respectively (p<0.05). The study results showed that the silage inoculants had the positive effects on quality increasing of rice straw silage; fermentative charateristics, fiber degradation and mycotoxins reduction. Ochratoxin A and zearalenone were greater reduction by adding bacterial inoculants of silage. Therefore it is considered that L. plantarum and S. cerevisiae will improve the quality and stability with remediation of mycotoxin in silage.

• Korean Journal of Breeding Science
• /
• v.51 no.4
• /
• pp.504-514
• /
• 2019

'Yechan' is a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance. It was a derived from a cross between 'Hopum' and 'Iksan537' (cultivar name 'Haepum'). 'Hopum' is a high grain quality mid-late maturing rice cultivar with strong lodging tolerance and 'Haepum' is a high grain quality medium maturing rice cultivar with multiple disease resistance. To shorten the breeding period, another culture method was applied to the F₁ plants. 'Yechan' was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for grain quality, lodging, and disease resistance. The heading date of 'Yechan' was August 14, one day later than that of 'Nampyeong'. 'Yechan' is a cultivar tolerant to lodging and it has short culms. It has multiple disease resistance against rice blast, rice stripe virus, and bacterial blight, including the K3a race, the most virulent race in Korea. The yield of 'Yechan' was similar to that of 'Nampyeong'. 'Yechan' showed excellent grain appearance, superior taste when cooked, and enhanced milling performance; thus, we concluded that it could contribute to the improvement of Korean japonica rice cultivar quality. 'Yechan', a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance, would be suitable for cultivation in the southern plain area in Korea and has been utilized in the breeding programs aimed at enhancing the grain quality and stability for the cultivation of Korean japonica rice (Registration No. 7647).

• Korean Journal of Agricultural Science
• /
• v.19 no.1
• /
• pp.40-50
• /
• 1992

This experiment was carried out to stimulate lactic starter culture for yoghurt manufacturing. A each of 1.5% of Bios 2000, CR starter medium, and Yeast extract were added to bulk medium, acidity, pH and changes in the number of lactic acid bacteria were investigated at, intervals of two hours for Lactobacillus bulgaricus and four hours for Streptococus thermophilus and Lactobacillus casei. The results obtained were summarized as follows. 1. The acidity of control arrived at 0.99% after 16 hours of incubation during the incubation of Lactobacillus bulgaricus. Whereas that of CR starter medium reached 1.00% at 12 hours of incubation. Yeast extract, 1.12% at 12 hours, and Bios 2000 reached 0.97% at 10 hours respectively, Thus, Bios 2000 showed the fastest rate of acid production. 2. When the acidity of experiment medium peaked on optimum levels. pH of control was 4.03 in 16 hours of incubation during the incubation of Lactobacillus bulgaricus. Whereas that of Bios 2000 reached 4.10 of Yeast extract reached 3.97 at 12 hours, and of CR starter medium reached 4.05 at 12 hours. 3. Lactic acid bacterial counts were $3.1{\times}10^{10}/ml$ after 16 hours of incubation during the incubation of lactobacillus bulgaricus, Whereas those of Bios 2000 reached $2.1{\times}10^{10}/ml$ at 10 hours, with the fastest stimulation of growth, The counts in CR starter medium were at $2.9{\times}10^{10}/ml$ at 12 hours, and Yeast extract were $3.8{\times}10^{10}/ml$ at 12 hours. 4. The acidity of control, CR starter medium, and Yeast extract reached 0.92% at 44 hours, and 0.96% at 32 hours, and 0.90% at 32 hours respectively, Also, that of Bios 2,000 reached 0.97% at 32 hours, which exhibited the highest, among the treatments. 5. The pH of control was 4.27 at 44 hours. that of CR starter medium was 4.33 at 40 hours and that of Yeast extract was 4.25 at 32 hours during the incubation in Streptococcus thermophilus. Besides, pH of Bios 2000 is lowest as 4.18 at 32 hours. 6. Lactic acid bacterial counts in control, CR starter medium, and Yeast extract during the incubation of Streptococcus thermophilus were $9.8{\times}10^{9}/ml$ at 44 hours,$9.5{\times}10^{8}/ml$ at 40 hours, and $9.6{\times}10^{8}/ml$ at 32 hours. And, the highest number was $2.0{\times}10^{9}/ml$ for Bios 2000 at 32 hours. 7. The acidity of control during the incubation of Lactobacillus casei reached 0.92% at 40 hours, and those of CR starter medium and Yeast extract were 0.95% at 40 hours, and 1.01% at 36 hours respectively. Also, Bios 2000 had the highest acidity as 0.94% at 32 hours. 8. The pH of control, CR starter medium and Yeast extract during the incubation Lactobacillus casei was 4.27 at 40 hours. 4.21 at 40 hours, and 4.15 at 36 hours respectively. Also, Bios 2000 showed the lowest pH, as 4.23, at 32 hours. 9. Lactic acid bacterial counts in control, CR starter medium and Yeast extract during the incubation of Lactobacillus casei were $9.4{\times}10^{7}/ml$ at 40 hours, $1.1{\times}10^{8}/ml$ at 40 hours, and $5.0{\times}10^{8}/ml$ at 36 hours respectively. And, the progress of 32 hours showed the highest number of lactic acid bacteria as$6.4{\times}10^{8}/ml$ in Bios 2000.

• Pediatric Infection and Vaccine
• /
• v.8 no.2
• /
• pp.191-198
• /
• 2001

Purpose : The purpose of this study was to investigate clinical features of hospitalized infants 28~90 days of age with fever without source and to analyze those of young febrile infants using risk criteria for serious bacterial infection. Methods : The clinical features of 131 infants 28~90 days of age admitted to the Ulsan Dong-Kang General Hospital Pediatric Department because of fever(temperature ${\geq}38^{\circ}C$ rectally) without source, from January 2000 to December 2000, were investigated by retrospective chart review. The clinical features of 131 febrile infants were analyzed using Rochester criteria. Results : Among 131 cases, there were 60 cases(45.8%) of urinary tract infection, 33 cases (25.2%) of aseptic meningitis, 2 cases(1.5%) of bacteremia and 36 cases(27.5%) of no specific diagnosis. Among 131 cases, there were 57 cases(43.5%) in low risk group and 74 cases(56.5%) in not low risk one by Rochester criteria. A significant difference in the incidence of urinary tract infection, aseptic meningitis and no specific diagnosis was not found between both groups. Male to female ratio was 1.8 : 1. Sex ratio between both groups was not significantly different. Most febrile infant were noted in spring(35.1%) and the summer(36.7%). The peak incidence of aseptic meningitis was noted in May and June. The fever subsided mostly within 48~72 hours after administering antimicrobial agents(61.8~83.2%). A significant difference in duration of fever after administering antimicrobial agents was not found between both groups. Conclusion : A selected group of low risk infants 28~90 days of age with fever without source can be managed as outpatients provided that a thorough initial evaluation is performed, that parents can reliably monitor their infant closely at home and that careful follow up can be assured. Because bag collected specimens were more likely to yield indeterminate urine culture result, a suprapubic or catheter obtained urine specimen for culture is a necessary part of the evaluation of all febrile infants 28~90 days of age. The further prospective study on evaluation and management of young febrile infant should be performed in our hospital.

• Tuberculosis and Respiratory Diseases
• /
• v.47 no.6
• /
• pp.775-785
• /
• 1999

Background : Though surgery plays an important role in the management of patients with Mycobacterium tuberculosis infection, there is little information regarding the timing of resection. We tried to find out the ideal timing of operation. Method: A retrospective review was performed in 69 patients underwent pulmonary resection for pulmonary tuberculosis between January 1993 and December 1997. They were categorized into various groups according to the length of preoperative specific drug therapy. The rates of treatment failure, realpse and complication in each group were compared statistically by $x^2$-test. Results: Eighty one point two percent were men and 18.8 % women with a median age of 33 years(range, 16 to 63 years). The mean number of resistant drugs was 3.l(range, 0 to 9). Patients were treated preoperatively with multidrug regimens, which mean number of preoperative specific drugs was 4.6, in an effort to reduce the mycobacterial burden with the mean length of preoperative drug therapy, 5.0 months. Postoperative treatment was conducted for a mean period of 13.0 months with a mean number of postoperative specific drugs, 4.4. Postoperative treatment failures were confirmed in 8 among 69 patients(11.6%). 2 of these 8 patients were showed up in the preoperative 3 to 4 months medication group and each of the rest was occurred in the preoperative 2 to 3, 5 to 6, 6 to 7, 12 to 13, 17 to 18 months, less than one month medication group, respectively. 59 of 69 patients were available for evaluation of the relapse rate with the mean duration of the postoperative follow-up, 19.8 months. In 4 patients bacterial relapse was confirmed(6.8%). Each of these 4 was in the preoperative 1 to 2, 2 to 3, 3 to 4, 5 to 6 months medication group. Categorized into various groups according to the length of preoperative specific therapy, there were no statistical significances of the treatment failure rate, relapse rate and complication rate in the groups. There were seven treatment failures of 28 who were AFB culture positive until the time of operation(25%, p<0.01). Categorized the preoperative AFB culture positive group into various groups according to the length of preoperative drug therapy, there were no statistical significances, either. Conclusion: We believe that operation plays an important ancillary role in the treatment of pulmonary tuberculosis. Our results indicate that the timing of resection according to the length of preoperative drug therapy may not cause trouble.

• Tuberculosis and Respiratory Diseases
• /
• v.51 no.6
• /
• pp.559-569
• /
• 2001

Background : Pleural effusion is one of the most common clinical manifestations associated with a variety of pulmonary diseases such as malignancy, tuberculosis, and pneumonia. However, there are no useful laboratory tests to determine the specific cause of pleural effusion. Therefore, an attempt was made to analyze the various types of pleural effusion and search for useful laboratory tests for pleural effusion in order to differentiate between the diseases, especially between a malignant pleural effusion and a non-malignant pleural effusion. Methods : 93 patients with a pleural effusion, who visited the Severance hospital from January 1998 to August 1999, were enrolled in this study. Ultrasound-guided thoracentesis was done and a confirmational diagnosis was made by a gram stain, bacterial culture, Ziehl-Neelsen stain, a mycobacterial culture, a pleural biopsy and cytology. Results : The male to female ratio was 56 : 37 and the average age was $47.1{\pm}21.8$ years. There were 16 cases with a malignant effusion, 12 cases with a para-malignant effusion, 36 cases with tuberculosis, 22 cases with a para-pneumonic effusion, and 7 cases with transudate. The LDH2 fraction was significantly higher in the para-malignant effusion group compared to the para-pneumonic effusion group [$30.6{\pm}6.4%$ and $20.2{\pm}7.5%$, respectively (p<0.05)] and both the LDH1 and LDH2 fraction was significantly in the para-malignant effusion group compared to those with tuberculosis [$16.4{\pm}7.2%$ vs. $7.6{\pm}4.7%$, and $30.6{\pm}6.4%$ vs.$17.6{\pm}6.3%$, respectively (p<0.05)]. The pleural effusion/serum LDH4 fraction ratio was significantly lower in the malignant effusion group compared to those with tuberculosis [$1.5{\pm}0.8$ vs. $2.1{\pm}0.6$, respectively (p<0.05)]. The LDH4 fraction and the pleural effusion/serum LDH4 fraction ratio was significantly lower in the para-malignant effusion group compared to those with tuberculosis [$17.0{\pm}5.8%$ vs. $23.5{\pm}4.6%$ and $1.3{\pm}0.4$ vs. $2.1{\pm}0.6$, respectively (p<0.05)]. Conclusion : These results suggest that the LDH isoenzyme was the only useful biochemical test for a differential diagnosis of the various diseases. In particular, the most useful test was the pleural effusion/serum LDH4 fraction ratio to distinguish between a para-malignant effusion and a tuberculous effusion.

• Korean Journal of Breeding Science
• /
• v.41 no.4
• /
• pp.654-659
• /
• 2009

"Cheongcheongjinmi" is a new japonica rice variety developed from a cross between Iri401 and Ilpumbyeo by the rice breeding team of National Institute of Crop Science, RDA. This variety is suitable for ordinary season culture of low level nitrogen application. Heading date of "Cheongcheongjinmi" is August 17, 4 days later than that of Sobibyeo in plain areas. It has culm length of 82 cm, and relatively semi-erect pubescent leaf blade and slightly tough culm tolerant to lodging with good canopy architecture. This variety has 13 tillers per hill, 126 spikelets per panicle and 90.2% of ripened grains. "Cheongcheongjinmi" showed lower spikelet fertility than Sobibyeo when exposed to cold stress. This variety showed slower leaf senescence and lower viviparous germination compared to Sobibyeo during the ripening stage. "Cheongcheongjinmi" is susceptible to blast disease, bacterial blight, virus diseases and planthoppers. The dried plant weight, total nitrogen and RuBisCO activity of "Cheongcheongjinmi" were higher than those of Sobibyeo in low level nitrogen application. The milled rice of "Cheongcheongjinmi" exhibits translucent, clear non-glutinous endosperm and medium short grain. It shows lower protein and amylose contents than those of Sobibyeo, and better palatability of cooked rice compared to Hwaseongbyeo. The milled rice yield of this cultivar is about 5.10 MT/ha at low level nitrogen application of ordinary season culture in local adaptability test for three years. Especially, "Cheongcheongjinmi" has better milling properties such as the percentage of whole grain in milled rice and milling recovery of whole grain, respectively than those of Sobibyeo. "Cheongcheongjinmi" would be adaptable to middle plain areas and middle-western coastal areas of Korea.

• Journal of Life Science
• /
• v.28 no.9
• /
• pp.1056-1061
• /
• 2018

This article reports an agar-degrading marine bacterium and characterizes its agarase. The agar-degrading marine bacterium, KC-1, was isolated from seawater on the shores of Sacheon, in Gyeongnam province, Korea, using Marine Broth 2216 agar medium. To identify the agar-degrading bacterium as Agarivorans sp. KC-1, phylogenetic analysis based on the 16S rRNA gene sequence was used. An extracellular agarase was prepared from a culture medium of Agarivorans sp. KC-1, and used for the characterization of enzyme. The relative activities at 20, 30, 40, 50, 60, and $70^{\circ}C$ were 65, 91, 96, 100, 77, and 35%, respectively. The relative activities at pH 5, 6, 7, and 8 were 93, 100, 87, and 82%, respectively. The extracellular agarase showed maximum activity (254 units/l) at pH 6.0 and $50^{\circ}C$ in 20 mM of Tris-HCl buffer. The agarase activity was maintained at 90% or more until 2 hr exposure at $20^{\circ}C$, $30^{\circ}C$ and $40^{\circ}C$, but it was found that the activity decreased sharply from $60^{\circ}C$. A zymogram analysis showed that Agarivorans sp. KC-1 produced 3 agar-degrading enzymes that had molecular weights of 130, 80, and 69 kDa. A thin layer chromatography analysis suggested that Agarivorans sp. KC-1 produced extracellular ${\beta}$-agarases as it hydrolyzed agarose to produce neoagarooligosaccharides, including neoagarohexaose (21.6%), neoagarotetraose (32.2%), and neoagarobiose (46.2%). These results suggest that Agarivorans sp. KC-1 and its thermotolerant ${\beta}$-agarase would be useful for the production of neoagarooligosaccharides that inhibit bacterial growth and delay starch degradation.

• The Korean Journal of Ecology
• /
• v.17 no.3
• /
• pp.299-310
• /
• 1994

Intraspecific clonal interactions have important influences on a population structure of the cellular slime mold (CSM). This study was to investigate whether or not evolutionary change in a population could be induced by clonal competition, and to elucidate how various clones in a population evolve in a homogeneous environment of laboratory culture. The characteristic clones of Polysphondylium pallidum which had different resource consumption rates (RCR) and mating types I and II were selected for study. Investigation was conducted for 4 experimental time interval $(T_0-T_4)$; one experimental time interval took almost 10-14 days from inoculation to havest of fruiting bodies. Two sets of 50 clones were cultured from 50 clones at To, and RCR variations of the population were compared between $(T_0\;and\;T_4)$ for each set of clones. Each clone of the CSM had a diverse resource consumption rate, or growth rate, in a homogeneous and limited Cerophyl agar plate despite the passage of 48-56 generations from the beginning of the experiment. Diverse clones with different growth rate could coexist in one site of the homogeneous agar plate as well as heterogeneous soil microenvironment. When there was high clonal diversity of RCR, a clone in a population had high chances to encounter other clones with resultant increased clonal competition. In one set, 26 of 37 clones of mating type I were changed to mating type Il for the 4 experimental time intervals, which indicated that the rate of competitive exclusion among clones during total experiment from $(T_0\;to\;T_4)$ was 0.703. In another set, 31 of 37 clones of mating type I were changed to mating type II , having the rate of competitive exclusion 0.838. The frequency of each of mat~ng types changed by 0.93-1.29% in each successive generation. The competitive exclusion among clones occurred by 1.26-1.75% when approximately $2.6{\times}10^8$ bacterial cells were provided as food and thereafter one generation of myxamoebae of CSM elapsed at room temperature. This finding implicated that in the vegetative state of P, pallidurn there was 1.26-1.75% probabil~ty of evolutionary change per generation changing from one clone to another clone.