The Salmonella typhimurium cdd gene encoding cytidine deaminase (cyti-dine/2'-deoxycytidine aminohydrolase; EC 3.5.4.5.) was isolated through shotgun clon-ing by complementation of the E. coli odd mutation. By subsequent deletion and sub-cloning from the

항생제 및 항균 물질 등의 오, 남용으로 인하여 항생제 내성균들이 등장, 사회적으로 큰 문제가 되고 있으며, 최근에는 식물이나 probiotics 등과 같이 항생제를 대체할 수 있는 물질에 대한 연구가 활발히 진행되고 있다. 이에 본 연구에서는 국내에서 오래 전부터 민간 요법으로 사용되어 오던 백련초 (Opuntia ficus-indica var. saboten)를 이용하여 in vitro와 in vivo에서 Salmonella enteyica serova. Enteritidis (S. enteritidis), S. enterica serova. Typhimurium (S. Typhimurium) DT104 및 Escherichia coli O157:H7에 대한 항균능을 평가하였다 백련초의 수용액이 포함된 Moulter Hinton agar에 Salmonella spp. 및 S. coli O157:H7를 접종한 결과 이들 균에 대한 억제능(inhibitory activity)을 확인할 수 있었다. 백련초 제제를 경구투여한 군에서 분변으로 배출되는 S.typhimurium DT104의 수가 급격히 감소하였고, 낀 후에는 더 이상 분변으로 균이 배출되지 않았으며, intestinal IgA가 유의적으로 증가함이 확인되었다. 본 연구를 통하여 백련초가 in vitro에서 S. enteritis, S. Typhimurium DT104와 E. coli O157:H7대한 항균력을 나타낼 뿐만 아니라 마우스의 gastrointestinal tract에서 역시 Salmonella에 대한 항균력을 보임을 확인할 수 있었다. 본 연구를 통해 백련초 및 그 성분을 이용한 병원성 세균의 제거 및 면역 증진 효과 등과 같은 연구의 필요성이 확인되었고, 그 응용 가능성도 매우 높을 것으로 사료된다.

In order to investigate the classification and antibiotic resistance of Salmonella species 718 isolates were isolated from patient in Seoul from 1996 to 2001. The two hundred and ninety eight isolates (41.5%) were identified as Sal. Enteritidis, followed by Sal. Typhi 218 isolates (30.4%), and Sal. Typhimurium 87 isolates (12.1%). The identified Salmonella species were most resistant to tetracycline (32.7%), followed by streptomycin (28.0%), ticarcillin (18.1%) and ampicillin (12.4%). Among isolates, 34.7% of Sal. Enteritidis were resistant to tetracycline, 32.3% to streptomycin, 23.2% to ticarcillin, 13.5% to ampicillin, respectively. 13.8% of Sal. Typhi were resistant to streptomycin, 10.6% to tetracycline, respectively. 66.7% of Sal. Typhimurium were resistant to tetracycline, 42.5% to streptomycin, 28.7% to ticarcillin, 26.4% to ampicillin and 17.2% to chloramphenicol, respectively. Of 718 isolates, 324 isolates (45.1%) were resistant to 1 or more drugs and 64 isolates (19.8%) were resistant to 1 drug, 132 isolates (40.7%) were resistant to 2 drugs, 50 isolates (15.4%) were resistant to 3 drugs, 27 isolates (8.3%) to 4 drugs, 27 isolates (8.3%) to 5 drugs, 22 isolates (6.8%) to 6 drugs. The most prevalent multiple resistant pattern was tetracycline-kanamycin (35.5%), followed by tetracycline-kanamycin-ticarcillin (8.3%), and tetracycline-kanamycin-ticarcillin-ampicillin (7.4%). Antibiotic resistant rate of Sal. Typhimurium was 73.6%, followed by Sal. Enteritidis 53.7% and Sal. Typhi 19.3%. Most Sal. Enteritidis was resistant to 1 drug or 2 drugs, whereas Sal. Typhi and Sal. Typhimurium were more resistant to 5 (16.7%) or 6 drugs (26.6%). The old generation antibiotics such as ampicillin, tetracycline, and streptomycin were annually more resistant than the new generation antibiotics such as ceftriaxone, ciprofloxacin or cefoxitin.

The polymerase chain reaction was used to selectively detect sequences within the fimbrial antigen of Salmonella enteritidis. Sterile milk was artificially inoculated with known amount of S. enteritidis and then DNA was extracted with guanidine thiocyanate/phenol/chloroform, followed by PCR. A detection limit of as few as 100 colony forming unit (cfu) per 0.5 ml milk was obtained with this method. For the whole procedure, it took only 5 h. A semi-quantitative polymerase chain reaction assay which allows an estimation of colony forming unit of S. enteritidis was developed. Known amount of standard plasmid pGem-4Z-Sef B(-) containing cloned S. enteritidis fimbrial antigen gene was co-amplified with Salmonella genomic DNA isolated from artificially inoculated milk. The same set of primers were used for the amplification and the products were cleaved with Bam HI. The concentration of the target DNA could be estimated by comparing the intensity of the two bands after electrophoresis. The PCR-based protocol described in this paper provides a rapid, simple, and sensitive method for detecting S. enteritidis in milk.

동치미액은 전통적으로 냉면국물로 이용되어왔다. 냉면국물의 미생물 오염문제를 해결하기 위하여 항균활성이 높은 김치 젖산균 Lactobacillus homohiochii B21과 Leuconostoc mesenteroides subsp. mesenteroides C16을 스타터로 혼합사용하여 동치미액을 제조하고, 이를 냉면국물에 100%, 50%, 10% 및 0% 첨가하여 20℃ 및 10℃에서 보관할 때에 동치미액의 항균력으로 인하여 의도적으로 첨가한 Salmonella typhimurium과 Staphylococcus aureus의 증식이 억제되는 정도를 조사하였다. 동치미액 100%인 냉면국물은 20℃에서 보관할 때는 Salmonella typhimurium은 16시간만에, Staphylococcus aureus는 32시간만에 10^6CFU/ml에서 10^0CFU/ml로 각각 급격히 사멸하였고, 10℃에서 보관할 때도 시간경과에 따라 생균수가 급격히 감소하였으나 감소속도는 20℃의 경우보다 느렸다. 동치미액을 50% 첨가한 육수에서도 Salmonella typhimurium과 Staphylococcus aureus는 시간경과에 따라 급격히 감소하였으며, 감소속도는 동치미액 100%일 경우보다 느렸다. 동치미액을 10% 첨가한 육수에서는 20℃에서 보관할 때는 초기에 Salmonella typhimurium과 Staphylococcus aureus의 균수증가가 약간 있었으나 동치미액 무첨가에 비하여 현저히 억제되었으며, 8시간∼16시간 이후부터는 균수가 서서히 감소하였다. 육수에 동치미액을 첨가하지 않았을 경우에는 20℃에서 보관할 때는 초기부터 Salmonella typhimurium과 Staphylococcus aureus의 균수증가가 급격히 이루어졌으며, 10℃에서 보관할 때는 24시간 이후부터 서서히 증가하였다. Salmonella typhimurium과 Staphylococcus aureus에 대한 본 동치미액의 억제력은 후자의 미생물보다 전자에 대하여 더 강하게 나타났다. 본 연구의 동치미액을 육수에 50% 첨가하여 냉면국물을 제조한다면 보관중의 미생물 오염문제 해결에 큰 도움이 될 것으로 판단된다.

This study was carried out to isolate and identify Salmonella species from poultry slaughterhouses and pork meat processing plants during the period from January 1997 to August 1998, and analyze resistance of antimicrobial agents and plasmid profiles of isolated Salmonella strains. A total of 15 Salmonella strains was isolated from poultry carcasses, swine carcasses, pork meats and cutting boards. Identified Salmonella strains were S. typhimurium, S. heidelberg, S. hilingdon, S. mbandaka, and S. virginia. Ten (66.7%) of 15 Salmonella strains showed resistance to antimicrobial agents and five strains (33.3%) of them were resistant to two or more antimicrobial agents. Plasmids were isolated from three Salmonella isolates which had two or more plasmids.

This study was performed to investigate the changes of amount of S. typhimurium during cooking processes using pork and japchae (a Korean food which is made from meat, vegetables and noodles), and to support a practical application to develop a hazard analysis critical control point (HACCP) model. The pork was purchased in a retail shop, cut (0.5 cm × 10 cm × 10 cm, 25 g), tested for Salmonella contamination (results : negative), inoculated with S. typhimurium (10^7 CFU/g), then treated in various conditions related to cooking. After thawing for 24 hours in various conditions, the number of S. typhimurium was increased to 10^(10) CFU/g at a refrigerated temperature (4-10℃), and to 10^(21) CFU/g at room temperature (22-29℃). After thawing in a microwave oven for 40 seconds, the number of S. typhimurium increased to l0^8 CFU/g. During the thawing period, the number of S. typhimurium increased over time. At the refrigerated temperature, the number of the bacteria was 10^(10) CFU/g after 24 hours, 10^(13) CFU/g after 48 hours, and 10^(20) CFU/g after 72 hours. At room temperature the number of bacteria reached 10^(11) CFU/g in 2 hours, 10^(15) CFU/g in 4 hours, 10^(16) CFU/g in 8 hours, 10^(18) CFU/ g in 12 hours, and 10^(21) CFU/g in 24 hours. After cooking in a frying pan (150±7℃) for 3 minutes, the bacterial count was 10^6 CFU/g. After cooking in hot water for 20 minutes, the bacterial count was 10^7 CFU/g at 60℃, 10^6 CFU/g at 63℃, and 10⁴ CFU/g at 65℃. The fried pork was mi×ed with cooked vegetables, noodles, sesame oil, sesame seeds, and seasonings to make Korean japchae. This process took 10±2 minutes. The bacterial count in the japchae increased to 10^7 CFU/g from the count of 10^6 CFU/g of the fried pork before it was mixed with the other ingredients. These results indicate that the amount of S. typhimurium is effected by various different cooking processes. This study can suggest that pork should be cooked in water at over 65℃ for 20 minutes in order to prevent food poisoning, if the pork is contaminated with S. typhimurium. The presence of S. typhimurium in the raw pork is identified in an HA for japchae, and the primary CCP for japchae is inadequate cooking (cooking method and time/temperature). We need to standardize time-temperature-size and amount of pork in cooking japchae, because pork is usually cooked in ordinary frying pans when we make this food.