Computer aided boar semen motility analysis for cereulide detection in different food matrices Andreja Rajkovic, Mieke Uyttendaele ⁎ , Johan Debevere Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Belgium Received 16 February 2006; received in revised form 22 September 2006; accepted 30 September 2006 Abstract Computer Aided Semen Analysis (CASA) study of the boar semen motility has been demonstrated to be an appropriate assay for detection of cereulide (Bacillus cereus emetic toxin). Application of the boar semen bio-assay to detect cereulide directly in foods requires investigation of potential interference of food components, preservatives and other microbial and chemical food contaminants with the bio-assay. Current study provides evidence that none of included Staphylococcus aureus enterotoxins A, B, C and D nor B. cereus Hemolysin BL (HBL) and non- hemolytic enterotoxin (NHE) and three mycotoxins (Sterigmatocystin, Fumonisin B1 and Patulin) exhibited a toxic impact on semen progressive motility. Aflatoxin M1, M3 and zearalenone impaired semen motility only at concentrations (0.004 mg ml - 1 , 0.1 mg ml - 1 and 10 mg ml - 1 , respectively) much higher than those found in foods and those permitted by legislation, in comparison to cereulide which induces motility cease at concentrations lower than 20 ng ml - 1 . Ten commonly used preservatives, namely potassium sorbate, sodium benzoate, (DL) malic acid, citric acid, (L+) tartaric acid, acetic acid, (DL) lactic acid, (L+) ascorbic acid, sodium chloride and sucrose induced no cease in spermatozoa motility even at preservative concentrations higher than permitted by legislation. Dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and acrylamide had no acute effect on spermatozoa motility at concentrations of 500 and 10,000 mg ml - 1 , respectively. Robustness of computer aided boar semen motility analysis, tested with 14 different foods inoculated with cereulide producing B. cereus, showed distinct cereulide production in seven samples (although B. cereus growth to counts higher than 8 log CFU g - 1 was noted in 11 samples), in amounts close to those reported in foodborne outbreaks. Test evaluation in 33 samples suspected to hold cereulide showed actual cereulide presence in ten samples and no interference of food matrix with the assay. © 2006 Elsevier B.V. All rights reserved. Keywords: Bacillus cereus; Cereulide; Computer aided semen analysis; Food; Enterotoxins 1. Introduction Cereulide, emetic toxin of Bacillus cereus, is recognized as the most perilous virulence factor from a wide spectrum of B. cereus pathogenesis. It is a causative agent of B. cereus related intoxications and is most commonly associated with farinaceous and starch rich products, where spores have survived cooking, germinated and allowed sufficient time at moderate temperature for growth and cereulide production to occur (Gibbs, 2003; Schoeni and Wong, 2005). Certain rice containing bakery products were found to hold cereulide in concentrations of 5–8 μgg - 1 (Jaaskelainen et al., 2003a,b). Even much lower concentrations of cereulide, ranging from 0.01 μgg - 1 up to 1.28 μgg - 1 , were reported in foods implicated in the emetic type of food poisoning (Agata et al., 2002). The clinical dose, suggested to be about 10 μg kg - 1 body weight (bw) (Paananen et al., 2002), is higher than those of some other known toxins (Staphylococcus aureus intoxica- tion that resembles symptoms of cereulide intoxication induces mild effects already at concentrations of 100 ng kg - 1 bw (Bergdoll, 1989)). The cereulide doses found in foods, although rarely, were in few occasions reported as lethal (Mahler et al., 1997; Dierick et al., 2005). Cereulide is a hydrophobic molecule that acts as an ionophore for potassium ions transporting them via the ion- International Journal of Food Microbiology 114 (2007) 92 – 99 www.elsevier.com/locate/ijfoodmicro ⁎ Corresponding author. Coupure links 653, B-9000 Ghent, Belgium. Tel.: +32 9 264 61 78; fax: +32 9 225 55 10. E-mail address: mieke.uyttendaele@UGent.be (M. Uyttendaele). 0168-1605/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2006.09.031