title: Molecular and toxigenic characterization of Bacillus cereus and Bacillus thuringiensis strains isolated from commercial ground roasted coffee.
abstract: Thirty samples of roasted ground coffee beans from 10 different commercial brands were analyzed to investigate the occurrence and levels of Bacillus cereus and Bacillus thuringiensis strains. Strains were evaluated for their genetic diversity by repetitive element sequence  polymorphism PCR (Rep-PCR) and for their toxigenic profiles, i.e., the presence of hblA, hblC, hblD, nheA, nheB, nheC, cytK, ces, and entFM. Survival and multiplication of B. cereus sensu lato in the ready-to-drink coffee was determined to evaluate this beverage as a possible  vehicle for B. cereus infection. B. cereus was detected in 17 (56.7%) of the 30 samples, and B. thuringiensis was detected in 8 (26.7%) of the 30 samples. Five samples did not produce any characteristic growth. The most common gene, entFM, was detected in 23 strains  (92%). The NHE complex (nheA, nheB, and nheC genes) was found in 19 strains (76%). The HBL complex (hblA, hblC, and hblD) was found in 16 strains (64%). All strains were negative for ces. The cytK gene was found in 16 strains (64%). The  computer-assisted cluster analysis of Rep-PCR profiles using a clustering criterion of 80% similarity revealed four main clusters. Cluster 1 was the predominant and comprised three B. thuringiensis strains with 100% similarity, cluster 2 comprised two B. cereus strains (100%  similarity), cluster 3 comprised two B. thuringiensis strains (90% similarity), and cluster 4 comprised one B. thuringiensis strain and one B. cereus strain (85% similarity). The cluster analysis of fingerprints generated by Rep-PCR revealed a high genetic diversity among  the B. cereus strains, suggesting that the contamination could have originated from different sources. In our experiments, when sugar was added and the beverage was kept in thermic bottles there was a significant increase in B. cereus sensu lato levels, which may increase the  risk of food poisoning. These results highlight the need for additional studies on this subject to better evaluate coffee as a food poisoning vehicle.
authors.affiliation: Laboratório de Fisiologia Bacteriana, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil 4365, Pavilhão Rocha Lima, Sala 312, Manguinhos, CEP 21045-900 Rio de Janeiro, Brasil.
authors.forename: Jeane Quintanilha
authors.initials: JQ
authors.lastname: Chaves
authors.forename: Clara de Fátima Gomes
authors.initials: Cde F
authors.lastname: Cavados
authors.forename: Adriana Marcos
authors.initials: AM
authors.lastname: Vivoni
mesh_terms: D001409:Bacillus cereus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D001413:Bacillus thuringiensis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D001628:Beverages / Q000382:microbiology*; D016000:Cluster Analysis; D003069:Coffee / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004768:Enterotoxins / Q000235:genetics*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005517:Foodborne Diseases; D014644:Genetic Variation; D006801:Humans
chemical_list: D003069:Coffee; D004269:DNA, Bacterial; D004768:Enterotoxins