Traceability of potential enterotoxigenic Bacillus cereus in beepollen samples from Argentina throughout the production process

ANA C. LÓPEZ; LETICIA A. FERNÁNDEZ; ADRIANA M. ALIPPI

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2020 vol. 334

0168-1605

Bee-pollen is a functional food sold for human and animal consumption butalso is a favorable microhabitat for many spore-forming bacteria. Amongthem, Bacillus cereus can produce several toxins and other virulence factors,causing an emetic or diarrheal syndrome after ingestion. The study involved36 bee-pollen samples obtained from different sampling points throughoutthe production process (collecting, freezing, drying, and cleaning) inArgentina. Fifty isolates of B. cereus yielded 24 different fingerprint patternswith BOX and ERIC primers. Only three fingerprint patterns weremaintained throughout the production process. In contrast, others were lostor incorporated during the different steps, suggesting that crosscontaminationoccurred as shown by differences in fingerprint patterns afterfreezing, drying, and cleaning steps compared to the initial collection step.Genes encoding for cereulide (ces), cytotoxin K (cytK), sphingomyelinase(sph), the components of hemolysin BL (hblA, hblB, hblC, hblD) and nonhemolyticcomplex (nheAB) were studied. All the isolates displayed one ormore enterotoxin genes. The most frequent virulence genes detected belongto the HBL complex, being the most abundant hblA (98%), followed by hblD(64%), hblB (54%), and hblC (32%), respectively. Ten strains (20%),present at all sampling points, carried all the subunits of the HBL complex.The non-hemolytic enterotoxic complex (nheAB) was found in 48 strains(96%), while seven strains (14%) present at all sampling points showed theamplification product for sphingomyelinase (sph). One cereulide-producerwas isolated at the cleaning step; this strain contained all the componentsfor the hemolytic enterotoxin complex HBL, the NHE complex, and K related to the foodborne diarrhoeal syndrome. In total, 11 differentvirulence patterns were observed, and also a correlation between repfingerprintand virulence patterns. The results suggest that bee-pollen canbe contaminated at any point in the production process with potentialenterotoxic B. cereus strains, emphasizing the importance of hygienicprocessing.