title: Plant compounds enhance the assay sensitivity for detection of active Bacillus cereus toxin.
abstract: Bacillus cereus is an important food pathogen, producing emetic and diarrheal syndromes, the latter mediated by enterotoxins. The ability to sensitively trace and identify this active toxin is important for food safety. This study evaluated a nonradioactive, sensitive, in vitro cell-based assay, based on B. cereus toxin inhibition of green fluorescent protein (GFP) synthesis in transduced monkey kidney Vero cells, combined with plant extracts or plant compounds that reduce viable count of B. cereus in food. The assay exhibited a dose dependent GFP inhibition response with ~25% inhibition at 50 ng/mL toxin evaluated in culture media or soy milk, rice milk or infant formula, products associated with food poisonings outbreak. The plant extracts of green tea or bitter almond and the plant compounds epicatechin or carvacrol were found to amplify the assay response to ~90% inhibition at the 50 ng/mL toxin concentration greatly increasing the sensitivity of this assay. Additional studies showed that the test formulations also inhibited the growth of the B. cereus bacteria, likely through cell membrane disruption. The results suggest that the improved highly sensitive assay for the toxin and the rapid inactivation of the pathogen producing the toxin have the potential to enhance food safety.
authors.affiliation: Foodborne Contaminants Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA. reuven.rasooly@ars.usda.gov.
authors.forename: Reuven
authors.initials: R
authors.lastname: Rasooly
authors.affiliation: Foodborne Contaminants Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA. bradley.hernlem@ars.usda.gov.
authors.forename: Bradley
authors.initials: B
authors.lastname: Hernlem
authors.affiliation: Foodborne Contaminants Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA. xiaohua.he@ars.usda.gov.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: He
authors.affiliation: Healthy Processed Foods Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA. mendel.friedman@ars.usda.gov.
authors.forename: Mendel
authors.initials: M
authors.lastname: Friedman
mesh_terms: D000818:Animals; D001409:Bacillus cereus / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry; D002522:Chlorocebus aethiops; D000081007:Cymenes; D004768:Enterotoxins / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000188:drug therapy / Q000382:microbiology; D049452:Green Fluorescent Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D041943:Infant Formula / Q000382:microbiology; D050296:Microbial Viability; D039821:Monoterpenes / Q000737:chemistry; D012275:Oryza / Q000382:microbiology; D010936:Plant Extracts / Q000737:chemistry*; D012680:Sensitivity and Specificity; D041942:Soy Milk; D013662:Tea / Q000737:chemistry; D014709:Vero Cells
chemical_list: D000081007:Cymenes; D004768:Enterotoxins; D039821:Monoterpenes; D010936:Plant Extracts; D013662:Tea; D049452:Green Fluorescent Proteins; D002392:Catechin; C073316:carvacrol