title: Surfactins in natto: the surfactin production capacity of the starter strains and the actual surfactin contents in the products.
abstract: Surfactin-type lipopeptides are suspected of being implicated in the rare food poisonings caused by Bacillus species outside the Bacillus cereus cluster. In order to get information on surfactin levels in actual human foods, bacilli from three commercial samples of a Japanese traditional bean product, natto, were isolated in order to clarify their potential to produce the suspect lipopeptides. The isolated bacilli were characterized as Bacillus subtilis. They were β-hemolytic and gave a positive signal in the PCR screen for genes associated with surfactin production, and their culture extracts were cytotoxic to boar sperm cells. Organic extracts of both Bacillus cultures and the natto samples were analyzed for their surfactin content using ultrahigh-performance liquid chromatography with high-resolution mass spectrometry. All the strains proved to be surfactin producers (15 to 39 μg/ml culture medium); the natto samples contained as much as 2.2 mg g(-1) of surfactins. This means that consumers can ingest at least approximately 80 to 100 mg of surfactins per single 50-g natto serving apparently without suffering any ill effects, indicating a very low human toxicity.
authors.affiliation: University of Eastern Finland and Institute of Public Health and Clinical Nutrition, P.O. Box 1627, 70211 Kuopio, Finland.
authors.forename: Mari
authors.initials: M
authors.lastname: Juola
authors.affiliation: University of Eastern Finland and Institute of Public Health and Clinical Nutrition, P.O. Box 1627, 70211 Kuopio, Finland.
authors.forename: Kristiina
authors.initials: K
authors.lastname: Kinnunen
authors.affiliation: Technical University of Denmark, Department of Systems Biology, Building 221, 2800 Lyngby, Denmark.
authors.forename: Kristian Fog
authors.initials: KF
authors.lastname: Nielsen
authors.affiliation: University of Eastern Finland and Institute of Public Health and Clinical Nutrition, P.O. Box 1627, 70211 Kuopio, Finland. atte.vonwright@uef.fi.
authors.forename: Atte
authors.initials: A
authors.lastname: von Wright
mesh_terms: D000818:Animals; D001409:Bacillus cereus; D001412:Bacillus subtilis; D003470:Culture Media / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000382:microbiology; D013058:Mass Spectrometry; D010456:Peptides, Cyclic / Q000302:isolation & purification* / Q000633:toxicity; D016133:Polymerase Chain Reaction; D045730:Soy Foods / Q000032:analysis* / Q000382:microbiology / Q000633:toxicity; D013552:Swine
chemical_list: D003470:Culture Media; D010456:Peptides, Cyclic