• 한국미생물·생명공학회지
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• 제34권1호
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• pp.52-57
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• 2006

새로운 고지혈증 예방 제품 개발을 위한 기초 자료를 얻고자 우선 전통 된장으로부터 HMG-CoA reductase 저해 물질을 강력하게 세포외로 생산하는 D-3 세균을 최종 분리 하였다. D-3 균의 미생물학적 특성을 조사한 결과 그람양성의 간균으로 운동성이 있었고 통성 혐기성이였다. 이들 특성과 16S rRNA 염기서열의 분석 결과 등을 종합하여 Bergey's manual로 동정한 결과 Bacillus cereus D-3로 동정되었다. HMG-CoA reductase 저해물질 생산 최적 조건을 조사한 결과 Bacillus cereus D-3를 glucose 2%, corn steep liquor $0.6%,\;K_{2}HPO_4\;0.04%,\;KH_{2}PO_4\;0.05%$를 함유한 Glucose-CSL 배지에 접종하여 $30^{\circ}C$에서 36시간 배양하여 얻은 상등액의 HMC-CoA reductase 저해활성이 39.4% 저해물질을 가장 많이 생성 하였다.

• 한국수산과학회지
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• 제13권4호
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• pp.163-171
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• 1980

최근 식중독 원인균으로 많이 보고되고 있는 Bacillus cereus균의 분포상태와 그 생리적 특성을 조사하기 위하여 1980년 5월부터 11월사이에 밥 32개, 김밥 20개, 떡 23개, 쌀 13개, 보리 13개 등 5종 총 101개 시료를 대상으로 B. cereus균의 분포상태와 그 생리화학상태, 용혈성과 증식속도 그리고 포자의 내열성을 실험한 결과를 요약하면 다음과 같다. 1. 미반류 75개 시료중에서 약 $35\%$에 상당하는 26개 시료와, 그 원료 26개 시료중 약 $54\%$에 상당하는 14개 시료에서 B. cereus균이 검출되었다. 또한 미반류에서는 B. cereus균의 검출율은 낮았으나 균주는 $10^{5-6}/g$으로 많았으며 쌀과 보리에서는 검출율은 높았으나 균주는 $10^3/g$ 정도로 적었다. 2. 총 40균주에 대한 생화학 실험결과 catalase, egg yolk reaction, gelatin hydrolysis, gucose fermentation 시험은 $100\%$ 양성반응을, 그리고 xylose, arabinose, mannitol oxidation 시험결과는 $100\%$ 음성반응을 나타내었다. 그밖에 Voges-Proskauer, citrate utilization, nitrate reduction, starch hydrolyis 시험결과는 균주에 따라 양성 또는 음성반응을 나타내었다. 3. 용혈성 양성균주는 40균주중 $70.0\%$에 상당하는 28균주였으며, 식중독 발생과 관계있는 용혈성 양성, 미분액화능 음성인 균주는 $38\%$에 상당하는 15균주이었다. 4. B. cereus균은 $10^{\circ}C$와 $50^{\circ}C$에서는 증식하지 않았으며 그 외 배양온도별 비증식속도와 평균 세대시간은 $20^{\circ}C$에서는 각각 $0.34hr^{-1},\;2.02hr$ 이었고, $30^{\circ}C$에서는 $0.73hr^{-2},\;0.95hr,\;35^{\circ}C$에서는 $0.79hr^{-1},\;0.88hr$, 그리고 $40^{\circ}C$에서는 $0.49hr^{01},\;1.44hr$이었다. 5. 포자의 내열성은 $D_{90}=29min,\;D_{95}=8.7min,\;D_{98}=3.7min$ 그리고 $D_{101}=2.3min$ 이었으며, z-value는 약 $10.5^{\circ}C$이었다.

• 한국축산식품학회지
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• 제35권2호
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• pp.272-276
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• 2015

The microbial distribution of raw materials and beef jerky, and the effect of nisin on the growth of Bacillus cereus inoculated in beef jerky during storage, were studied. Five strains of pathogenic B. cereus were detected in beef jerky, and identified with 99.8% agreement using API CHB 50 kit. To evaluate the effect of nisin, beef jerky was inoculated with approximately 3 Log CFU/g of B. cereus mixed culture and nisin (100 IU/g and 500 IU/g). During the storage of beef jerky without nisin, the number of mesophilic bacteria and B. cereus increased unlikely for beef jerky with nisin. B. cereus started to grow after 3 d in 100 IU nisin/g treatment, and after 21 d in 500 IU nisin/g treatment. The results suggest that nisin could be an effective approach to extend the shelf-life, and improve the microbial safety of beef jerky, during storage.

• 한국식품위생안전성학회지
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• 제23권4호
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• pp.343-347
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• 2008

최근 식사대용으로 각광을 받는 선식은 포장 후 더 이상 가열 처리 과정 없이 섭취하는 식품으로 포자를 형성하여 열처리 과정에서 완전히 사멸되지 않으며 생존하는 B. cereus에 의한 위해성이 문제시되고 있다. 따라서 시중에서 유통되고 있는 선식에 대한 B. cereus정량을 통해 오염 수준을 파악한 결과 선식 161점 중 57점 (35.4%)에서 B. cereur가 검출되었고 검출된 시료 57점 중에 100 FU/g 미만은 21점, 100-1000 CFU/g 미만은 33점, 1,000 CFU/g 이상은 3점이 검출되었다. 선식에서 분리한 B. cereus의 생화학적 특성을 통해 독소 형태를 알아본 결과는 enterotoxin 양성이 93%이며 emetic toxin 의심 균주는 5.3%였다. 이러한 B. cereus의 저감화를 위한 방안의 일환으로 선식의 제조 과정에서 B. cereus의 열처리 과정에 대한 사멸 정도를 측정하였다 측정한 결과 tryptic soy broth에 포자를 접종한 결과는 75, 80, 85, 90에서 40.3분, 8.8분, 3.3분, 1.1분이였다. 용질에 따라 수분 활성도가 낮아지면 열에 대한 저항성이 높아지므로 선식에 시료에 대한 D-value를 시험한 결과 $75^{\circ}C$, $80^{\circ}C$, $85^{\circ}C$, $90^{\circ}C$에서 37.1분, 22.5분, 4.9분, 3.1분이였다. Z-value는 tryptic soy broth에서는 $9.8^{\circ}C$이며 선식 시료에서는 $12.8^{\circ}C$였다. 따라서 선식에서 B. cereis에 대한 관리가 요구되어진다.

• Food Science and Biotechnology
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• 제17권3호
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• pp.603-607
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• 2008

Thirteen commercial antimicrobial products were examined to assess the sporicidal activity against Bacillus cereus spores at room temperature, 60 and $85^{\circ}C$. Neither the antimicrobials showed detectable antimicrobial activity against the B. cereus spores nor induced spore germination after the treatment at 0.5 or 1.0%(w/v, v/v) commercial antimicrobial agents at room temperature for 0.5 to 4 hr. However, when the antimicrobials such as chitosan, lactic acid, fermented pollen, grapefruit extract were applied with heat at $85^{\circ}C$ for 30 min, more than 1 log CFU/mL spores were additionally inactivated compared to only heat treatment without antimicrobials. Imposition of $60^{\circ}C$ to B. cereus spores with the higher concentration of 5.0%(v/v) lactic acid or 2.5%(w/v) thiamine dilaurylsulfate for the longer time incubation of 24 hr resulted in 3 log CFU/mL spore inactivation. This work showed that low concentrations of commercial antimicrobials by themselves did not inactivate B. cereus spores. However, when physical processes such as heat were combined together, antimicrobials showed a synergistic effect against B. cereus spores.

• 한국미생물·생명공학회지
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• 제44권3호
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• pp.254-260
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• 2016

Doenjang samples were prepared by inoculation of multiple starters consisting of two Bacillus spp., one yeast, and one fungus. Doenjang A was fermented with Bacillus amyloliquefaciens EMD17, B. amyloliquefaciens MJ1-4, Pichia farinosa SY80, and Rhizopus oryzae. Doenjang B and C were fermented with the same yeast and fungus but different Bacillus strains; namely, B. amyloliquefaciens EMD17 and B. subtilis CH3-5 for doenjang B, and B. amyloliquefaciens MJ1-4 and B. subtilis CH3-5 for doenjang C. Doenjang D was fermented with microorganisms present in rice straw (control). The doenjang samples were spiked with B. cereus ATCC14579 at two different levels, 10⁴ CFU/g doenjang (I) and 10⁷ CFU/g doenjang (II). All eight doenjang samples were fermented for 70 days at 25℃. Growth of B. cereus was inhibited in doenjang A, B, and C, with the bacterial cell count after 70 days being less than the initial 10⁴ CFU/g added, whereas B. cereus was not inhibited in doenjang D. Doenjang B showed the strongest inhibitory activity against B. cereus, with a cell count of less than 10³ CFU/g after 42 days, even when B. cereus was initially added at 10⁷ CFU/g. Some properties of the doenjang samples, such as pH, TA, and amino-type nitrogen content, were similar to those of doenjang fermented with starters only. The results indicate that carefully selected starters can effectively prevent the growth of B. cereus during doenjang fermentation.

• Food Science and Biotechnology
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• 제15권3호
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• pp.458-461
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• 2006

To determine whether the toxicity of Bacillus cereus would be seen in human cell lines and mice, we screened B. cereus B-38B, B. cereus B-50B, and B. cereus KCCM40935 for genes that coded for 5 enterotoxins using the polymerase chain reaction and cultivated them for 17 hr, by whose time they had grown to $10^7-10^8$ colony-forming units (CFU) per milliliter. Cell-free supernatant was added to make up 1% of the total reaction solution. Human cells from normal lung, lung carcinoma, embryonic kidney, and cervical adenocarcinoma cell lines were grown in culture. The cytotoxicity induced by adding the reaction solution was indicated by cell death rates of 0 to 70%, depending on the bacterial strain involved and the cell line. A lethality of 20% was observed when B. cereus cultures containing $10^7-10^8$ viable cells were administrated orally to mice. Therefore, the culture of B. cereus containing $10^7-10^8$ viable cells seems to have high cytotoxicity on human cell lines and lethality on mice.

• 한국축산식품학회지
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• 제31권1호
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• pp.40-46
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• 2011

The growth profile of Bacillus cereus in ready-to-eat (RTE) food products of animal origin was examined under different temperature and incubation conditions. In sandwiches and Kimbab, B. cereus did not grow or exhibited only minimal growth at 4 and $10^{\circ}C$, but it grew rapidly at ambient temperature. In sandwiches, B. cereus did not grow efficiently at $25^{\circ}C$, however, in ham, the main ingredient of sandwiches, B. cereus growth was observed at the same temperature, with bacterial levels reaching 7.94 Log CFU/g after incubation for 24 h at $25^{\circ}C$. Toxigenicity of B. cereus was observed only at temperatures above $25^{\circ}C$. In Kimbab, B. cereus produced toxin after 9 h at $30^{\circ}C$ and after 12 h at $25^{\circ}C$. Ingredients of sandwiches and Kimbab were collected from 3 different Korean food-processing companies to investigate the source of contamination by B. cereus. Among the 13 tested food items, 6 items including ham were found to be contaminated with B. cereus. Of these ingredients, B. cereus isolates from 3 items produced enterotoxins. None of these isolates harbored the emetic toxin-producing gene. The findings of the present study can be used for risk assessments of food products, including ham and cheese, contaminated with B. cereus.

• 한국식품과학회지
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• 제47권5호
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• pp.593-598
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• 2015

This study determined the thermal resistance of Bacillus cereus, Escherichia coli O157:H7, and Listeria monocytogenes in multi-grain soymilk and proposes processing conditions that meet the national standard for retort food products in Korea. D and z values were calculated from thermal inactivation kinetic curves after heating at 55, 60, and $65^{\circ}C$. The D value for B. cereus at $55^{\circ}C$ was the highest (22.8 min), followed by that for E. coli O157:H7 (18.8 min) and L. monocytogenes (17.6 min). At $60-65^{\circ}C$, the order was L. monocytogenes ($D_{60-65^{\circ}C}=3.4-0.9min$), E. coli O157:H7 (3.0-0.3 min), and B. cereus (1.2-0.3 min). The z values for these species were 5.2, 5.5, and $7.7^{\circ}C$, respectively. The Korean national standard for retort food products was achieved by thermal processing at $124{\pm}2^{\circ}C$ for 0.3-2.2 min. This study provides useful data for ensuring both the microbiological safety and product quality of multi-grain soymilk products.

• 한국수산과학회지
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• 제53권6호
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• pp.870-877
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• 2020

Twenty-three Bacillus cereus strain isolated from commercial jeotgal were investigated for 11 toxin genes and susceptibility to 25 different antimicrobials. The hemolytic enterotoxins hblA, hblC, and hblD were detected in 13.0%, and non-hemolytic enterotoxins nheA, nheB, and nheC were detected in 26.1%, 100%, and 100% of the isolates, respectively. The positive rates of cytK, entFM, becT, hlyII, and ces were 73.9%, 60.9%, 26.1%, 8.7%, and 0.0%, respectively. According to the disk diffusion susceptibility test, all of the strains studied were resistant to cefuroxime, followed by cefoxitin (78.3%), oxacillin (78.3%), ampicillin (69.6%), penicillin G (69.6%), and amoxicillin (65.2%). However, all the strains were susceptible to 11 other antimicrobials, including amikacin, chloramphenicol, and ciprofloxacin. The average minimum inhibitory concentrations of amoxicillin, ampicillin, and cefuroxime against B. cereus were 462.9, 235.0, and 135.0 ㎍/mL, respectively. These results highlight the need for sanitizing commercial jeotgal, and provide evidence to help reduce the risk of jeotgal contamination by antimicrobial-resistant bacteria.