시중에 유통 중인 샐러드와 김밥을 각각 100종 수거하 여 B. cereus 함량을 정량분석하였다. 샐러드는 불검출이 54종이었으며 10 CFU/g 이하가 8종, 100 CFU/g 이하가 25 종, 1,000 CFU/g 이하가 11종이었으며 1,000 CFU/g 이상 인 것이 2종이었다. 샐러드의 대한 모니터링 결과 평균은 1.18 log CFU/g 이었으며 표준편차는 0.71 log CFU/g이었다. 김밥에서는 100개의 검체중 20개의 검체에서 B. cereus가 검출되었으며 평균은 1.01 log CFU/g 이었으며 표준편차는 0.71 log CFU/g이었다. 모니터링 결과를 이용하여 통계적 검체채취 방법을 수립하고자 하였다. 검체채취 방법은 국제미생물위원회에서 제공하는 검체채취프로그램인 NEW sampleplan program을 이용하였으며 검체갯수를 고정한 후 미생물 기준인 m과 M, 그리고 허용한계값인 c 값을 변화 하면서 산출되는 합격률이 0.95에 가장 근사한 값을 선정 하였다. 그 결과 샐러드, 김밥에서의 가장 적합한 검체채취 기준은 3분법을 사용하는 것으로 n = 5, c = 0, m = 1,000, M = 10,000과 n = 5, c = 2, m = 100, M = 1,000의 기준이 설정되었다. 특히 후자에 서술된 기준은 현재 뉴질랜드에서 즉석섭취식품에서의 B. cereus에 대한 규격으로 사용하고 있어 국제적인 경향에도 부합함을 알 수 있었다.

살균제 저항성 Bacillus cereus 분리주의 포자에 살균제와 열을 가해 그 병합효과를 비교하였다. 사용된 B. cereus 균주는 차아염소계 처리 후 분리한 균주(S-BC-50, S-BC-52), 과산화수소 처리 후 분리한 균주(S-BC-23, S-BC-48), acetic acid 처리 후 분리한 균주(S-BC-54, S-BC-56)와 표준균주 B. cereus KCTC1661을 사용하였다. B. cereus 분리주의 포자를 다음 조건으로 처리하였다; i) 0.56% 과산화수소수(HP), ii) 3% acetic acid(AA), iii) 80oC 열처리(H80), iv) 90o 열처리(H90), v) HP+H80, vi) HP+H90, vii) AA+H80, viii) AA+H90. 포자를 HP와 AA 처리에 노출시킨 결과 포자가 감소하지 않았지만, H80과 H90 처리에서는 1~2 log CFU/mL가 감소하였다(P<0.05). 병합처리(HP+H80, HP+H90, AA+H80, AA+H90)에 포자를 적용시킨 경우, 포자수가 3-6 log CFU/mL 감소 하였지만, AA+H80과 AA+H90은 AA만 처리했을 때보다 오히려 포자 제어가 감소했다. 따라서 HP와 열처리를 병합했을 때는 B. cereus 포자를 불활성화하기에 효과적이지만, AA의 경우 B. cereus 포자가 열처리에 대한 저항성을 증가시키는 것으로 사료된다.

This study was performed to compared the effectiveness of individual treatments (electrolyzed water: EW, organic acid, and ultrasound) and their combination on reducing foodborne pathogens from perilla leaves. Perilla leaves were innoculated with a cocktail of Salmonella Typhimurium, Staphylococcus aureus, Bacillus cereus. Inoculated perilla leaves were treated with EW combined with different concentration of acetic acid (0.5%, 1.0%, 1.5%, 2.0%) for 1 min at room temperature. Treatment of 3 pathogens on perilla leaves with electrolyzed water combined with ultrasound (25 kHz) and 0.5% acetic acid was also performed for 1 min. While the numbers of S. Typhimurium and B. cereus showed reduced with increasing acetic acid concentration, there is no difference in the number of S. aureus treated with EW containing 0.5% to 1.5% acetic acid. Discoloration was observed the perilla leaves treated with EW combined with more than 1.0% acetic acid. For all three pathogens, the combined treatment of EW and ultrasound resulted in additional 0.42 to 0.72 log10 CFU/g. The maxium reductions of S. Typhimurium and B. cereus were 0.95, 1.23 log10 CFU/g after treatment with EW combined with 0.5% acetic acid and ultrasound simultaneously. The results suggest that the treatment of EW combined with 0.5% acetic acid and ultrasound increased pathogens reduction compared to individual treatment.

The effect of pt-I values of 6.5, 6.0, 5.0, and 4.0 on spore germination of Bacillus cereus (B. cereus) was investigated at water activity (a%) values of 0.98, 0.96, 0.94, and 0.90 in a controlled medium at 30°C for 7 days. The best condition for germination of spores of B. cereus was observed at pH 6.5 with aw 0.98. No matter what combination of a and pH is used, a complete inhibition of spore germination was achieved at either a,.. value of 0.90 or pH value of 4.0. Spore germination was also delayed or inhibited at aw 0.98 with pH 4.0, aw 0.96 with pH 5.0, and aw 0.94 with pH 6.5, 6.0, 5.0, or 4.0. The results indicate that the combined inhibitory effects of pH and water activity on the germination of B. cereus spores in controlled medium could be applied to food preservation.

Bacillus cereus is widely distributed on various foods and is known to cause clinical infections, food poisoning toxin induced diarrhea and vomiting. In this study, B. cereus group detected and analyzed rice, rice bran, and biofilm characterization of B. cereus confirmed. B. cereus was identified in approximately 34.6% of brown rice and 50.0% of rice bran. B. thuringiensis was detected in 3.9% of brown rice and 23% of rice bran, and B. mycoides was isolated from rice bran. The microtiter plate assay detected differences in biofilm-forming ability among B. cereus group isolates. Biofilm of B. cereus seemed to increase the MIC values of antimicrobial agent and antibiotic compounds compared with planktonic cells. Therefore, sufficient attention should be given to good manufacturing practice and good agriculture practice to avoid contamination of B. cereus group raw material including rice.

This study was practiced to survey food-borne bacterial aspects of Escherichia coli and Bacillus cereus etc. from 210 processed seasoned marine products in Garak fishery wholesale market in Seoul, 2009. Distributions of these bacterial isolates were 28 coliforms, 32 Bacillus spp., 71 Staphylococcus spp., 11 Listeria spp, and 10Enterococcus spp. in 157 dried squids, 23 dried file fishes, and 20 dried pollacks etc. respectively. Results in 16 kinds of antibiotics susceptibility test by disc diffusion method, special multiple drugs resistance patterns were NOR + LVX + CIP + SAM+ VA + S + TE + CF, SAM + C + VA, VA + S + TE, and VA + S in 9 E. coli strains, also,AMC + SAM + CF, SAM + CF, and VA + CF in 21 Bacillus cereus strains respectively. On the basis of the results above, many seasoned dried fishes had multiple drugs resistances, conclusively, we suggest limited guideline and special management on use of antibiotics in floating net cages of fishery farms.

Bacillus cereus is a gram-positive spore-forming bacterium and produces an emetic or diarrheal syndrome induced by an emetic toxin and an enterotoxin, respectively. In this study, the effect of different types of media, temperature, and time on the sporulation of B. cereus, and thermal resistance of B. cereus spores produced in various temperatures were evaluated. The highest levels of spores were detected when they are produced at 25℃. There were no significant differences in levels of spores produced at 25℃ among culture media and times while levels of spores produced at 43℃ were significantly reduced with the increase of time. However, thermal resistance of B. cereus spores could be affected by incubation temperature. In fact, higher D-values (12.0, 10.1, and 5.9 min for 2, 4, and 6 weeks, respectively) of spores produced at 43℃ were observed than did in samples produced at other temperatures (25 and 37℃). D-values of spores were 7.7, 8.2, and 12.0 min when they were produced at 25, 37, and 43℃ for 2 weeks, respectively. The sporulation of B. cereus at 25℃ could result in high amounts of spores however the sporulation at 43℃ for 2 weeks could be effective to produce thermal resistant spores.

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 문제시 되고 있다. 따라서 시중에서 유통되고 있는 선식에 대한 B. cereus정량을 통해 오염 수준을 파악한 결과 선식 161점 중 57점 (35.4%)에서 B. cereus가 검출되었고 검출된 시료 57점 중에 100 CFU/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 사멸정도를 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 ℃, 80 ℃, 85 ℃, 90 ℃에서 37.1분, 22.5분, 4.9분, 3.1분이였다. Z-value는 tryptic soy broth에서는 9.8 ℃이며 선식 시료에서는 12.8 ℃였다. 따라서 선식에서 B. cereus에 대한 관리가 요구되어진다.

Agarooligosaccharides were produced by β-agarase from Bacillus cereus ASK 202. LD_(50) of Agarooligosaccharides was determined to be 1359 mg/kg which corresponded to GRAS material. Agarooligosaccharides at 5% level exhibited 88.3% inhibition on TA98 and 54% on TA100, indicating agarooligosaccharides to be potent antimutagenic substance. Immunologic activity of agarooligosaccharides was also confirmed by mouse spleen cell culture. Agarooligosaccharides addition of 200 ㎕/ml stabilized spleen cells (2.5 × 10^6 cells/ml) as compared to control (6.4 × 10⁴ cells/ml).

Agar, one of the most abundant marine products has not been utilized extensively because of low level of processing technology in Korea. This research was carried out to improve the utilization of agar and consequent increase in profit. Antibacterial activity of agarooligosaccharides were evaluated against bacteria causing putrefaction and food poisoning. Addition of 0.4% agarooligosaccharides showed antibacterial activity toward Staphylococcus aureus and Escherichia coli O157:H7; furthermore, autoclave treatment of agarooligosaccharides solution enhanced the antibacterial activity. Agarooligosaccharides showed high stability against the pH change. Addition of amino acid(alanine, lysine, glycine, phenylalanine) in agarooligosaccharides solution enhanced antibacterial activity in E. coli O157:H7, Streptococcus mutans and Staphylococcus aureus.

Bacillus cereus B-amylase was purified by Sephadex G-100 gel filtration, CM Sephadex C-50 ion exchange chromatography and CM Sephadex C-50 ion exchange rechromatography. The purified enzyme showed 871unit/㎎ of specific activity. The purified enzyme was identified as homogenious by disc PAGE, SDS-PAGE and analysis of reaction product. The purified enzyme showed optimum pH 7.0. optimum temperature 50℃, and was stable at 0∼50℃ and at pH range of 6∼10.

인삼 추출물인 saponin이 Bacillus cereus의 성장에 미치는 영향을 세포의 성장 및 영양물질의 세포내 유입 정도와 효소 활성도를 관찰함으로써 알아보았다. 인삼 saponin을 Bacillus cereus의 배양액에 첨가하였을 때, 영양물질의 세포내 유입이 증가하고 이들 물질의 대사와 관련된 효소의 활성도가 증가하는 것으로 나타났다. 또한, saponin에 의해 Bacillus cereus 개체군의 전반적인 성장이 증가하였다. 성장의 증가 현상은 인삼 saponin이 세포막에 먼저 작용하여 세포의 영양물질 흡수 통로인 영양물질 결합 부위를 노출시켜 영양물질의 흡수를 증진시킨데 기인한 것으로 사료되는 바이다.