title: Bacillus cereus and Bacillus thuringiensis spores in Korean rice: prevalence and toxin production as affected by production area and degree of milling.
abstract: We determined the prevalence of and toxin production by Bacillus cereus and Bacillus thuringiensis in Korean rice as affected by production area and degree of milling. Rough rice was collected from 64 farms in 22 agricultural areas and polished to produce brown and white rice. In total, rice samples were broadly contaminated with B. cereus spores, with no effect of production area. The prevalence and counts of B. cereus spores declined as milling progressed. Frequencies of hemolysin BL (HBL) production by isolates were significantly (P ≤ 0.01) reduced as milling progressed. This pattern corresponded with the presence of genes encoding the diarrheal enterotoxins. The frequency of B. cereus isolates positive for hblC, hblD, or nheB genes decreased as milling progressed. Because most B. cereus isolates from rice samples contained six enterotoxin genes, we concluded that B. cereus in rice produced in Korea is predominantly of the diarrheagenic type. The prevalence of B. thuringiensis in rice was significantly lower than that of B. cereus and not correlated with production area. All B. thuringiensis isolates were of the diarrheagenic type. This study provides information useful for predicting safety risks associated with B. cereus and B. thuringiensis in rough and processed Korean rice.
authors.affiliation: Department of Food Bioscience and Technology, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-701, Republic of Korea.
authors.forename: Booyoung
authors.initials: B
authors.lastname: Kim
authors.affiliation: Department of Food Bioscience and Technology, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-701, Republic of Korea.
authors.forename: Jihyun
authors.initials: J
authors.lastname: Bang
authors.affiliation: Division of Human Environmental Sciences, Wonkwang University, Shinyong-dong, Iksan, Jeonbuk 570-749, Republic of Korea.
authors.forename: Hoikyung
authors.initials: H
authors.lastname: Kim
authors.affiliation: Korea Food Research Institute, Baekhyun-dong, Seongnam, Gyeonggi 463-746, Republic of Korea.
authors.forename: Yoonsook
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Korea Food Research Institute, Baekhyun-dong, Seongnam, Gyeonggi 463-746, Republic of Korea.
authors.forename: Byeong-Sam
authors.initials: BS
authors.lastname: Kim
authors.affiliation: Center for Food Safety and Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Griffin, GA 30223-1797, USA.
authors.forename: Larry R
authors.initials: LR
authors.lastname: Beuchat
authors.affiliation: Department of Food Bioscience and Technology, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-701, Republic of Korea. Electronic address: escheri@korea.ac.kr.
authors.forename: Jee-Hoon
authors.initials: JH
authors.lastname: Ryu
mesh_terms: D001409:Bacillus cereus / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D001413:Bacillus thuringiensis / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D003257:Consumer Product Safety; D004768:Enterotoxins / Q000378:metabolism*; D005506:Food Contamination / Q000032:analysis* / Q000706:statistics & numerical data; D005511:Food Handling; D012275:Oryza / Q000382:microbiology*; D056910:Republic of Korea; D013171:Spores, Bacterial / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004768:Enterotoxins
keywords: Bacillus cereus; Bacillus thuringiensis; Enterotoxin; Milling; Rice