• 한국식품영양과학회지
• /
• 제24권2호
• /
• pp.293-298
• /
• 1995

Antimicrobial effect of tea extracts from green tea(steamed, roasted), oolong tea and black tea was investigated. Minimal inhibitory concentration(MIC) of tea extraxcts against 9 well known strains of foodborne pathogenic bacteria such as the Gram positive and Gram negative bacteria was determined at 37$^{\circ}C$. Significant antimicrobial activity was observed in the steamed green tea and the roasted green tea of the water-soluble fraciton, and the steamed green tea of the methanol-soluble fraction, and the steamed green tea, roasted green tea and the oolong tea of the crude catechin fraction. The MIC of these extracts against B. subtillis were 700$\mu\textrm{g}$/ml, 500$\mu\textrm{g}$/ml and 120 $\mu\textrm{g}$/ml, respectively. The crude catechin fraction possessed greater antimicrobial activity than did the other fractions. Among tea extracts, extracts of steamed green tea, roasted green tea and oolong tea showed higher antimicrobial activity than them of black tea. The MIC of the crude catechin fraction obtained from tea extracts against Gram-positive bacteria such as M. Iuteus, B. subtillis and S. mutans were 30~50$\mu\textrm{g}$/ml, 120~240$\mu\textrm{g}$/ml and 120~180$\mu\textrm{g}$/ml, and against Gram-negative bacteri such as e. aerogenes and V. parahaemolyticus were 50~60$\mu\textrm{g}$/ml and 60~70$\mu\textrm{g}$/ml in the broth medium, respectively. Especially, the MIC to Streptococcus mutans which has known as a causative bacteria of a decayed tooth were 120$\mu\textrm{g}$/ml, 140$\mu\textrm{g}$/ml, 180$\mu\textrm{g}$/ml and above 1,000$\mu\textrm{g}$/ml in steamed green tea, roasted green tea, oolong tea and black tea, respectively. Tea extracts had strong growth inhibition activity against foodborne pathogenic and dental bacteria.

• Asian-Australasian Journal of Animal Sciences
• /
• 제32권7호
• /
• pp.1052-1061
• /
• 2019

Objective: This study was conducted to identify duck liver-expressed antimicrobial peptide 2 (LEAP-2) and demonstrate its antimicrobial activity against various pathogens. Methods: Tissue samples were collected from 6 to 8-week-old Pekin ducks (Anas platyrhynchos domesticus), total RNA was extracted, and cDNA was synthesized. To confirm the duck LEAP-2 transcript expression levels, quantitative real-time polymerase chain reaction was conducted. Two kinds of peptides (a linear peptide and a disulfide-type peptide) were synthesized to compare the antimicrobial activity. Then, antimicrobial activity assay and fluorescence microscopic analysis were conducted to demonstrate duck LEAP-2 bactericidal activity. Results: The duck LEAP-2 peptide sequence showed high identity with those of other avian species (>85%), as well as more than 55% of identity with mammalian sequences. LEAP-2 mRNA was highly expressed in the liver with duodenum next, and then followed by lung, spleen, bursa and jejunum and was the lowest in the muscle. Both of LEAP-2 peptides efficiently killed bacteria, although the disulfide-type LEAP-2 showed more powerful bactericidal activity. Also, gram-positive bacteria was more susceptible to duck LEAP-2 than gram-negative bacteria. Using microscopy, we confirmed that LEAP-2 peptides could kill bacteria by disrupting the bacterial cell envelope. Conclusion: Duck LEAP-2 showed its antimicrobial activity against both gram-positive and gram-negative bacteria. Disulfide bonds were important for the powerful killing effect by disrupting the bacterial cell envelope. Therefore, duck LEAP-2 can be used for effective antibiotics alternatives.

• 약학회지
• /
• 제32권4호
• /
• pp.222-229
• /
• 1988

A series of substituted benzylthioalkanamidocephalosporins 3a-3p were synthesized and tested in vitro antibacterial activity. Of these new cephalosporins exhibited good antibacterial activity against Gram-positive bacteria whereas none of the compounds possessed the activity against Gram-negative bacteria at the concentration tested.

• Bulletin of the Korean Chemical Society
• /
• 제8권3호
• /
• pp.189-192
• /
• 1987

The syntheses of mercaptotetrazoles and cephalothin analogs are described. Their in vitro potency was established. The compounds exhibited high antibacterial activity against Gram-positive bacteria and moderate activity against Gram-negative bacteria.

• 한국환경보건학회지
• /
• 제33권2호
• /
• pp.104-114
• /
• 2007

This study evaluated the airborne concentrations of bacteria, Gram-negative bacteria, and fungi in waiting rooms, wards, and outdoors, according to time and particle size between October 17 and November 28, 2003. The geometric mean number of airborne bacteria was highest in the morning. The more people there were, the higher was the total bacteria concentration. The concentration of fungi was also highest in the morning. Temperature and relative humidity affected the concentrations of fungi significantly (p<0.05). This study found relationships between microorganism concentrations and (actors such as time, place, temperature, humidity, ventilation, and number of people. Therefore, to manage the pollution resulting from airborne microorganisms, each time, place, and environmental factor should be examined periodically, and the number, size, and movement of airborne microorganisms should be evaluated.

• Clinical and Experimental Pediatrics
• /
• 제50권1호
• /
• pp.56-64
• /
• 2007

목 적 : 소아 종양 환자에서 발열이 있는 경우, 즉각적인 경험적 항생제 치료가 필요하기 때문에, 지역이나 병원 내에서 발생한 균혈증의 흔한 원인균과 항생제 감수성에 대한 최근 경향에 대한 정보가 필요하다. 본 연구에서는 4년간 소아 종양 환자에서 분리된 균혈증의 원인균 분포와 이들의 항생제 감수성에 대하여 분석하고자 하였다. 방 법 : 2002년 1월부터 2005년 12월까지 서울대학교 어린이병원 소아 종양 환자 128명 환아에서 발생한 197례의 균혈증과 이들에서 분리된 214균주에 대하여 분석하였다. 결 과 : 총 214균주 중 그람음성균이 64.0%, 그람양성균이 31.3%였으며 진균은 4.7%이었다. 균혈증을 일으킨 가장 흔한 균은 Klebsiella species(21%)와 E. coli(16.8%)였으며, CNS와 viridans streptococci도 7.9%와 7.5%로 분리율이 높았다. 호중구 감소증이 있는 환자군에서 그람음성균이 차지하는 비율이 감소증이 없는 환자군에 비해 높았고(67.5% vs. 51.1%, P=0.018), 균혈증 발생 당시 중심 정맥관을 가진 경우에 CNS(12.7% vs. 2.1%, P=0.004)와 viridans streptococci(11.0% vs. 3.1%, P=0.036)가 차지하는 비율이 더 높았다. 항생제 감수성 검사에서 그람양성균에서는 penicillin, oxacillin 및 vancomycin 내성률이 각각 83.3%, 48.5% 및 0.5%였으며, 그람음성균에서는 cefotaxime, piperacillin/tazobactam, imipenem, gentamicin 및 amikacin 내성률이 24.1%, 17.2%. 6.6%, 21.6% 및 14.2%이었다. 균혈증의 경과를 알 수 있었던 179례 중 42례(23.5%)가 중환자실 치료를 받았으며, 20례(11.2%)가 사망하였으며, 그람 음성균 감염의 경우 그람 양성균 감염에 비해 중환자실 치료율이 높았으며(26.5% vs. 10.3%, P=0.016), 중심 정맥관을 가진 경우에 중환자실 치료 빈도(34.4% vs. 10.8%, P<0.001)와 사망률(16.7 % vs. 4.8%, P=0.012)이 높았다. 결 론 : 최근 4년간 소아 종양 환자에서의 균혈증 분석 결과, 아직 그람음성균이 차지하는 빈도가 높으며 특히 호중구 감소증이 동반되었을 때 그람음성균에 대한 적절한 치료가 우선 시행되어야 하겠다. 하지만 그람양성균이 차지하는 비율이 증가하고 있는 것도 경험적 항생제 결정시 고려하여야 할 것으로 판단된다.

• 한국축산식품학회지
• /
• 제43권3호
• /
• pp.402-411
• /
• 2023

This study was conducted to investigate the bactericidal effect of nisin (Nisin) only, atmospheric pressure plasma (APP) only, and a combination of APP and nisin (APP+Nisin)(APP+Nisin) on beef jerky and sliced ham inoculated with Escherichia coli O157:H7, gram-negative bacteria. The bactericidal effect against E. coli O157:H7 and Listeria monocytogenes was confirmed using a nisin solution at a concentration of 0-100 ppm, and APP+Nisin was tested on beef jerky and sliced ham using 100 ppm nisin. Beef jerky and sliced ham were treated with APP for 5 min and 9 min, respectively. In the bacterial solution, 100 ppm nisin out of 0-100 ppm nisin exhibited the highest bactericidal activity against L. monocytogenes (gram-positive bacteria; p<0.05); however, it did not exhibit bactericidal effects against E. coli O157:H7 (gram-negative bacteria). The APP+Nisin APP+Nisin exhibited a 100% reduction rate in both E. coli O157:H7 and L. monocytogenes compared to the control group, and was more effective than the Nisin. The APP+Nisin decreased the number of colonies formed by 0.80 and 1.96 Log CFU/g for beef jerky and sliced ham, respectively, compared to the control, and exhibited a higher bactericidal effect compared to the Nisin (p<0.05). These results demonstrate the synergistic bactericidal effect of APP and nisin, providing a possible method to improve the limitations of nisin against gram-negative bacteria. In addition, this technology has the potential to be applied to various meats and meat products to control surface microorganisms.

• The Plant Pathology Journal
• /
• 제15권2호
• /
• pp.79-86
• /
• 1999

• Archives of Pharmacal Research
• /
• 제17권2호
• /
• pp.131-133
• /
• 1994

New istain-3-isonicotinylhydrazones, isationazine and its Mannich bases and spiro (indoline-3,2'-thiadiazoline)-2-one have been synthesized. These compounds have been screenced for their antibacterial activity against the Gram-positive and Gram-negative bacteria.

• 한국식품위생안전성학회지
• /
• 제10권2호
• /
• pp.65-71
• /
• 1995

Bacteriocins from lactic acid bacteria have attracted much attention in recent years because of their useful worth in increasing safety and extending shelf life of foods. These substances show an inhibitory effect against some food spoilage bacteria and food-borne pathogens. The inhibitory effect fo the bacteriocin produces by lactic acid bacteria against Listeria monocytogenes(L. monocytogenes) was examined in this study. The culture supernatants of 5 kinds of bacteria among the 10 kinds of testes lactic acid bacteria had the inhibitory activity against Listeria sp., various Gram positive and Gram negative bacteria. Bacteriocin produced by Lactobacillus plantarum(Lact. plantarum) LMG 7945 was the most active toward L. monocytogenes. Bacteriocin production of the Lact. plantarum LMG 7945 cultured on MRS broth was increased late logarithmic phase over early stationary phase. This bacteriocin was stable at heat treatment and acidic pH relatively; The activity was retained after heating at 121$^{\circ}C$ for 15min and was active in the pH range of 2~4 but was lost above pH 5.