With a rabbit model, the present study was performed to examine the effect of Escherichia coli lipopolysaccharide (E. coli LPS) on hormones. Cortisol, epinephrine, and norepinephrine concentrations in LPS-treated groups were high at all sampling periods (from 3 hrs to 72 hrs) as compared to control group (p$lt;0.05 or p$lt;0.01). The each peak time was at respectively 24 hrs, 3 hrs, and 12 hrs. Insulin and glucagon concentrations in LPS-treated groups elevated up to 12 hrs (p$lt;0.01 or p$lt;0.05) with a each peak point at 12 hrs or 6 hrs, while those of the rest sampling points (from 24 hrs to 72 hrs) were lower than that of control (p$lt;0.05). Increase of cortisol concentration was generally dose-dependent, whereas the changes of the other hormones were irregular patterns. These observations show that E. coli LPS lead to releases of stress hormones such as cortisol, epinephrine, and norepinephrine and disturbances of endocrine systems. These LPS-induced hormonal disorders may cause physiologically fatal results.

To investigate the effects of bacterial endotoxin on lipids and cytokines, and to explain the relationships between their changes, we carried out this study using experimentally Escherichia coli (E. coli) endotoxin-induced septicemic rabbits. The triglyceride and cholesterol concentrations in endotoxin groups were generally high (p$lt;0.01 or 0.05) at all sampling time points (from 3hr to 24 hr), while phospholipid concentrations in endotoxin groups elevated in dose-dependent fashion at 3hr and 6hr after endotoxin injection compared to control group (p$lt;0.05). There were significant negative correlations between lipids changes and cytokines (TNF-α and IL-1β) each other (p$lt;0.05), and endotoxic rabbits having higher triglyceride of cholesterol levels shown relatively better conditions compared with others. As a result, the alterations in the lipid compositions caused by endotoxin may imply an active exhibition of the host defense mechanism rather than the disturbances of lipid metabolism.

본 연구는 병원성 Escherichia coli O157 : H7에 의한 감염을 예방하기 위하여 알칼리에서의 적응성과 항균요법제에 의한 불확실성화 효과를 조사하였다. Escherichia coli O157 : H7은 고 농도의 알칼리 (pH 11.5)에 노출 후, pH 9에서의 증식이 pH 7에서보다 좀 더 저항성이 있게 나타나 알칼리에서의 적응능력이 강했다. 이러한 알칼리 적응성은 pH 9에서 6시간 이내에서 잘 나타났다. 한편 Escherichia coli O157 : H7은 항균요법제 중 saicin 과 ceftnaxone에서 감수성이 매우 높았고, 반면, erythromycin과 yosamycin에서는 저항성이 높았다. 또한 saicin과 ceftriaxone에 5∼100kGy로 감마선을 조사하여도 균주의 최소발육저해농도(MIC)에는 영향을 미치지 않았다.

벼의 엽록체 small HSP의 고온 스트레스 하에서의 기능을 밝히기 위하여 Oshsp21 cDNA를 pET 발현 vector에 도입하였다. 형질전환된 대장균 배양액에 IPTG를 첨가하여 단백질 발현을 유도시킨 다음 고온 stress 하에서의 생존율을 대조구와 비교하였다. 그 결과 대조균주의 경우 에서의 생존율이 크게 감소하였으나 Oshsp21이 발현된 대장균의 경우 70% 이상의 생존율을 나타내었다. 또한 대장균 단백질을 에서 30분간 열처리한 후, 대장균 단백질을 가용성과 비가용성 단백질로 분획한 다음, 각각의 비율을 조사한 결과, 대조균주의 경우 총 단백질의 약 60%가 비가용성 단백질로 변성되었으나, Oshsp21을 발현시킨 대장균의 경우 총 단백질의 약 35%만이 비가용성 단백질로 나타났다. 이러한 결과는 벼의 엽록체 small HSP는 세포내에서 분자 chaperone으로 기능하여 고온내성을 부여할 수 있음을 나타낸다.

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 Listeria monocytogenes와 Escherichia coli O157:H7의 증식이 억제되는 정도를 조사하였다. 동치미액 100%인 냉면국물은 20℃에서 보관할 때에 Listeria monocytogenes는 8시간만에, Escherichia coli O157:H7는 40시간만이 10^6CFU/ml에서 10^0CFU/ml로 각각 급격히 사멸하였고, 10℃에서 보관할 때에도 시간경과에 따라 생균수가 급격히 감소하였으나 감소속도는 20℃에서 보관할 때보다 느렸다. 동치미액을 50% 첨가한 육수에서도 Listeria monocytogenes와 Escherichia coli O157:H7는 시간경과에 따라 급격히 감소하였으며, 감소속도는 동치미액 100%일 경우보다 느렸다. 동치미액을 10% 첨가한 육수는 20℃에서 보관할 때는 초기에 Listeria monocytogenes 및 Escherichia coli O157:H7의 균수증가가 약간 있었으나 동치미액 무첨가에 비하여 현저히 억제되었으며, 16시간 이후부터는 균수가 서서히 감소하였다. 동치미액을 첨가하지 않은 육수는 20℃에서 보관할 때는 초기부터 Listeria monocytogenes 및 Escherichia coli O157:H7의 균수증가가 급격히 이루어졌으며, 10℃에서 보관할 때는 24시간 이후부터 서서히 증가하였다. Listeria monocytogenes 및 Escherichia coli O157:H7에 대한 본 동치미액의 항균활성은 후자의 미생물보다 전자에 대하여 더욱 강하게 나타났다. 본 연구의 동치미액을 육수에 50% 첨가하여 냉면국물을 제조한다면 보관중의 미생물 오염문제 해결에 큰 도움이 될 것으로 판단된다.

최근 산업의 발달로 인한 식품의 안전성에 대한 국민의 우려가 증가되고 있으며 특히 식품을 미생물의 증식으로부터 안전하게 보존하기 위한 천연식품보존제의 개발이 요구되고 있다. 지구상에 풍부한 천연자원인 키토산과 합성화학보존제인 소르빈산을 사용하여 그람음성 병원성 식중독 원인균인 E. coli O157:H7과 대표적 그람양성 식중독 원인균인 Staph. aureus에 대해 실험한 결과는 다음과 같았다. 5. coli O157:H7에 대한 키토산의 최소발육억제농도는 pH 5.0에서 500 ppm, pH 5.5에서 250 ppm, pH 6.0에서 500 ppm, 그리고 pH 6.5에서 2000 ppm이었으며, Staph. aureus에 대한 키토산의 최소발육억제농도는 pH 5.0에서 31.3 ppm이었으며 , pH 5.5 이상에서는 62.5 ppm이었다. 소르빈산의 최소발육억제농도는 pH 5.0에서 500 ppm, pH 5.5에서 1500 ppm, 그리고 PH 6.0 이상에서는 2000ppm이상이었다. Staph. aureus에 대한 소르빈산의 최소발육억제농도는 pH 5.0에서 1500ppm이었으며, pH 5.5 이상에서는 2000 ppm 이상이었다. E. coli O157:H7에 대한 키토산과 소르빈산의 병 용처리효과는 pH에 크게 영향을 받아 pH 6.5에서는 키토산농도 500 ppm과 소르빈산 500 ppm농도에 발육이 억제되었으나 pH 5.0에서는 키토산농도 250 ppm과 소르빈산 31.3 ppm에 억제되었다. 한편, Staph. aureus에서는 pH에 대한 영향이 별로 없었으며, 키토산의 영향을 크게 받으나 소르빈산의 영향은 거의 없었다. pH 6.5, 37℃의 조건하에서 E. coli O137:H7은 키토산 500 ppm 및 소르빈산 500 ppm 처리와 키토산 250 ppm 및 소르빈산 250 ppm 병용처리군에서 모두 증식이 억제되었으나 키토산과 소르빈산 단독처리군에서는 배양시간이 증가함에 따라 균의 증식이 계속되었다. Staph. aureus는 소르빈산에 영향을 받지않았으며 병용효과보다는 키토산에 대한 영향이 컸다. pH 5.5, 37℃의 조건하에서 E. coli O157:H7은 키토산 500 ppm, 250 ppm 단독첨가시와 병용처리시 모두 3시간 이내에 균증식이 억제되었다. Staph. aureus의 경우는 키토산 50 ppm 단독처리군과 키토산 25 ppm과 소르빈산 2000 ppm 병용처리군에서 균증식이 사면되었다. E. coli O157:H7에 대한 키토산과 소르빈산병용처리시 MIC와의 상관관계는 pH 6.5에서 R=0.95(p<0.01), pH 6.0에서 R=0.99(p<0.01), pH 5.5에서 R=0.97(p<0.01), 그리고 pH 5.0에서 R=0.99(p.0.01)로 높은 상관관계를 나타내었다. Staph. aureus에 대해서는 소르빈산의 병용처리에 의한 효과는 거의 없었다. 이상의 결과로 종합하면 pH변화에 따른 키토산과 소르빈산 단독 및 병용처리로 인한 상승효과를 확인할 수 있었으며 이 결과 천연식품인 키토산을 병용함으로써 인체에 영향이 있는 합성화학보존제인 소르빈산의 양을 감소시킬 수 있었으며, 또한 식품의 보존성을 더 증가 또는 유지시킬수 있을 것으로 기대되었다.

본 연구 E. coli O157:H7에 대한 LP system(lactoperoxidae/thiocyanate/hydrogen peroxide)의 항균효과를 측정하기 위해 수행되었다. 초기 접종수준(10^2, 10^4, 10^7 cfu/ml), LP의 농도(10 ppm, 20 ppm, 30 ppm), 배지종류 (TSB, UHT milk, raw milk), 배양온도(5℃, 10℃, 15℃) 등에 따라 E. coli O157:H7에 대한 항균효과를 측정, 비교한 결과, 초기 접종수준을 10^2/ml으로 하였을 때와 LP의 농도를 10 ppm 및 5℃ 배양에서 항균력이 가장 높게 나타났다.

A study was undertaken to determine the thermal inactivation of Escherzchia coli O157:H7 as influenced by the effects of temperature, time, suspension medium and ascorbate. Tryptic soy broth was more heat resistant than phosphate buffer (pH 7.1), with D values of 1.52-1.68 min at 60℃ and 1.51-1.63 min at 70℃ compared with 1.52-1.65 min at 60℃ and 1.26-1.61 min at 70℃ for phosphate buffer as suspension medium. E. coli O157:H7 was completely inhibited within 30 min when small inoculum (10^6 CFU/ml) was heated at 70. When E. coli O157:H7 was preheated at 48℃ for 60 min in phosphate buffer before heating, D values were 1.28-1.60 min at 60℃, and 1.13-1.56 min at 70℃, showing that preheating increases the heat resistance of the strain. Phosphate buffer containing ascorbate (0.001 M) was enhanced the thermal inactivation of the strain when inoculated as large inoculum (10^9 CFU/ml), while ascorbic acid was no effect at low cell concentrations (10^6 CFU/ml).

This study was intended that the biochemical patterns, bioserological characteristics, resistance of antibiotics, and transferable resistance patterns of 35 Escherichia coli strains from 79 fish and shellfish samples in marine markets from August to October, 1995. The Standard plate count, coliforms and fecal coliforms were also counted in the 79 cases and analysed the correlationship each other. Geometric means of Standard plate count in seawater fish, shellfish, mollusca and crustacean were 1.4 × 105 CFU/g, 4.0 × 10^5 CFU/g, 2.4 × 10^5 CFU/g, 4.7 × 10^5 CFU/ g, and those of coliforms were 1.3 × 10¹ CFU/g, 4.8 × 10³ CFU/g, 8.9 × 10² CFU/g, 5.8 × 10³ CFU/g. There were no fecal coliforms in the fish and mollusc. However, the geometric means of coliforms in the shellfish and crustacean (1.1 × 10¹ CFU/100g, 10 CFU/100 g) were less than those of fish and mollusca. The important biochemical characteristics of E. coli distinguished from the shellfish and crustacean were motility, ornithine decarboxylase, mucate, esculin. The fermentative properties of E. coli were also sucrose, salicin, sorbitol, and raffinose. Of 35 isolates of E. coli, 13 strains (37.1%) showed the pathogenic O antisera, which were O:27 3 strains (23.1%), O:159 2 strains (15.4%) and O:148, O:119, O:142, O:158, O:136, O:18, O:128, and O:168 1 strain (7.7 %), respectively.

Effects of benzoate (0-0.6 g/l and sorbate (0-2.0 g/l) on the growth of Escherichia coli O157:H7 in tryptic soy broth at various pH levels (4-8) and temperatures (4℃, 37℃) were investigated. Benzoate and sorbate were inhibited the growth of E. coli 0157:H7 up to 12 hours cultivation at 4℃, and 2.0 g/l sorbate was only inhibited during 48 hours cultivation at 37℃. Among the pH levels tested, pH 4 showed significant inhibitory effect against the E. coli O157:H7 on 4℃ and at 37℃, respectively. When used in combination 0.2 g/l benzoate and sorbate were completely inhibited the growth of E. coli O157:H7 on pH 4 and at 37℃. While on pH 5 at 4℃, all of the concentration tested did not exert any inhibitory effect. The combined effects were retarded more than single treatment of E. coli O157:H7.

The growth inhibition effect of orally administrated yogurt ACE and Metchnikoff upon E. coli O157:H7 and S. typhimurium inoculated into gastric lumen of rabbits was investigated. The rabbits challenged with each 1 ml of suspension containing 10^8 CFU/ml of the pathogens were divided into 4 groups by the interval of yogurt administration: A group; preadministrated 7 days before inoculation of the pathogens and fed daily; B group; administrated daily after inoculation of the pathogens, C group; administrated every 3 days after inoculation of the pathogens; Control group, not fed after inoculation of the pathogens. Each 3 ml of yogurt containing 10^9 CFU/ml was orally administrated into rabbits. All yogurt administrated groups (A, B, C) showed growth inhibition effect on E. coli O157:H7 in one day after inoculation of the pathogen by the level of 0.8-1.0 log CFU/g, compared with the result differences between the control group and the yogurt administrated groups. In the control group after 5 days of inoculation, the number of colonized pathogens was 10^5-10^6 CFU/g, whereas 10³-10⁴ CFU/g was detected in the yogurt administrated groups. After 10 days of inoculation, the viable pathogen number per gram (g) of the rabbit feces was 10³ CFU/g in the control group, whereas the number below 10¹ CFU/g was detected in the group A, and 10² CFU/g in the group B and C. The growth inhibition effect of yogurt administration on E. coli O157:H7 was highly increased in the order of A, B, and C group. The same effect on S. typhimurium was observed at the level of 2 log CFU/g in the Metchnikoff yogurt administrated groups, compared with the control group result in one day after inoculation of the pathogen. In 7 days after inoculation of the pathogen, the viable number was increasingly decreased, and finally after 15 days no viable cell of S. typhimurium was discharged into the fecal samples in the group A, and the mean level of 10¹ CFU/g was detected in the group B, but there was no growth inhibition effect in the group C. The growth inhibition effect on S. typhimurium was observed at the same level of viable cell number between the yogurt ACE administrated groups and the control group in 5 days after inoculation. But, after 10 days of inoculation the viable cell number was started to decrease, and the viable cell of S. typhimurium was not discharged from rabbit intestinal contents after 15 days of inoculation in the yogurt ACE administrated groups. In such a case that yogurt was administrated in order to prevent the pathogens, pre-administration on a daily basis one week before inoculation of the pathogens exerted considerable effect in growth inhibition. In comparison with two kinds of yogurt tested in this study, the growth inhibition effect on two kinds of pathogens was observed more highly in the Metchnikoff administrated group than the ACE administrated group.

Lactobacillus acidophilus NCFM, Lactobacillus casei YIT 9018, Bifidobacterium longum 8001, and Bifadobacterium longum 8025 at the level of 10^6 cfu/ml were cultured with 10⁴ cfu/ml of Escherichia colt O157:H7 KSC 109 or Salmonella typhimurium ATCC 14028, in order to verify the effects of lactic acid bacteria and bifidobacteria on the growth of the pathogens. In the mixed culture of lactic acid bacteria with E. colt O157:H7 KSC 109, growth inhibition and atypical microcolonies of E. colt O157:H7 KSC 109 were observed. The pathogens inoculated grew for 5 hours (pH 5.3), by the time L. acidophilus NCFM reached the exponential growth phase, and then the surviving pathogens were decreased to 10¹ cfu/ml after 35 hours. When L. casei YIT 9018 was grown with the pathogens, they grew for 10 hours (pH 4.6), by the time L. casei YIT 9018 reached the end of exponential growth phase, and then the surviving pathogens were decreased drastically. Up to the stationary growth phase of lactic acid bacteria, L. acidophilus NCFM exhibited stronger inhibition against the pathogens than L. casei YIT 9018 did, which might be attributed to its faster growth. Likewise bifidobacteria inhibited the growth of the pathogens. tested, bifidobaceria was weaker in the inhibitory activity than lactic acid bacteria. When Bifidobacterium longum 8001 was cultured with the pathogens, E. colt O157:H7 KSC 109 was gradually inhibited at the stationary growth phase of bifidobacteria, atypical microcolonies were formed on Levine EMB medium after 48 hours, and Salmonella grew up to 10^6 cfu/ml, then was drastically inhibited at the exponential growth phage of Bifxdobacterium longum 8001. But when Bifidobacteriuam longum 8025 was cultured with the pathogens, the pathogens grew to the same level of Bifidobacteriuam longum 8025 after 10 hours, then the surviving pathogens were decreased drastically.

Escherichia coli O157:H7 and Salmonella ser. typhimurium are pathogens involved in food poisoning in numerous countries. This study aimed to obtain knowleges on the survival of E. coli O157:H7 KSC 109 and S. ser. typhimurium ATCC 14028 in fermented milk products which were on sale in Suwon Yakult supplier. To the final concentration of 10³-10⁴ cfu/ml of E. coli O157:H7 KSC 109 or S. ser. typhimurium ATCC 14028 in the fermented milks, Metchnikoff, Ace, Yakult, Mastoni and Super100 were inoculated with these pathogens and then were stored at 4 and viable cells of these pathogens were periodically counted. The results showed that the survival of two pathogens differed in the different types of fermented milks tested. Number of surviving E. coli O157:H7 KSC 109 and S. ser. typimurium ATCC 14028 cells (initial inoculum, 10³-10⁴ cfu/ml) were decreased to 10', 102 cfu/ml in Ace after 100 hours, and were decreased gradually to 10¹ cfu/ml in Yakult after 250 hours. In the other fermented milks, viable cells of E. coli O157:H7 KSC 109 was not drastically decreased but those of S. ser. typhimurium ATCC 14028 was decreased gradually to 10² (Mastoni), and to 10¹ cfir/ml (Super100) after 250 hours. It appeared that S. ser. typhimurium ATCC 14028 was more susceptible than E. coli O157: H7 KSC 109 at low pH. Vibale cells of E. coli O157:H7 KSC 109 was not drastically decreased in most of fermented milks tested except Ace and Yakult, but in general, S. ser. typhimurxum ATCC 14028 was drastically decreased in most of the fermented milks. The major inhibition factor against these pathogens in the fermented milks during storage at 4℃ appeared to be the acidity and the metabolites produced by the starters bacteria used in fermented milk products.

Surface swab samples from beef (188), pork (240) and chicken (95) carcasses were collected from slaughterhouse in Kangwon and Kyunggi areas from March through July 1996. The samples were examined on the level of E. coli biotype I relevant to fecal contamination due to unsanitary processing control and the existence of verocytotoxin-producing E. coli (VTEC). E. coli biotype I were confirmed from 38.8% of beef, 40.0% of pork, and 69.5% of chicken carcasses. Little variation was noted among three sampling points; rump, flank and neck of beef, ham, belly and jowls of pork. E. coli O157:H7 was only confirmed from 2 of 188 beef carcasses. E. coli O157 were isolated from 6.4% of beef, 2.5% of pork, and 1.1% of chicken carcasses among E. coli biotype I. All the isolated E. coli O157 showed positive for vero cell cytotoxicity test. Isolation rate of E. coli O157 in summer was higher than in spring. In case of pork and chicken carcasses, E. coli O157 was isolated in summer only.

Vibrio vulnificus에서 lipopolysaccharide(LPS)를 추출하여 지방산 조성을 분석한 후 이 결과를 Escherichia coli LPS와 Salmonella typhimurium LPS의 것들과 비교하였다. Vibrio vulnificus LPS의 주 지방산은 myristic acid(C14:0, 41.37%)이었고 Escherichia coli LPS는 lauric acid(C12:0, 37.03%), Salmonella typhimurium LPS는 capric acid(C10:0, 48.60%)로 서로 달랐으나 이 세가지 지방산이 각 LPS의 주성분이었다(70%이상).