title: Molecular methods to evaluate biodiversity in Bacillus cereus and Bacillus thuringiensis strains from different origins.
abstract: The spore-forming genus Bacillus includes species of industrial, clinical and environmental significance. The possibility of differentiating between Bacillus cereus and Bacillus thuringiensis, toxin producers associated with illness, is a real need in monitoring potentially contaminated foods to understand the real distribution of B. cereus/B. thuringiensis in different outbreak cases. As the use of DNA comparison obtains clearer results than classical microbiological methods in distinguishing B. cereus from B. thuringiensis in this work PCR-TTGE (Temporal Temperature Gradient gel Electrophoresis), rep-PCR and RAPD-PCR methods have been compared to assess the intra- and inter-specific variability of B. cereus and B. thuringiensis. 80 strains of B. cereus and B. thuringiensis isolated from food, patients and pesticides were analyzed using a gyrB gene DNA sequence in TTGE; primer M13 in the RAPD-PCR and primers REP1DT and REP2DT in the rep-PCR methods. A widespread distribution of the electrophoretic profiles was obtained either for B. cereus or for B. thuringiensis using TTGE. rep-PCR and RAPD-PCR were not always able to group strains from the same origin or belonging to the same species. The fingerprints obtained with the rep- and RAPD-PCR methods confirm the high intraspecific variability present in B. cereus and B. thuringiensis indicating the difficulty to discriminate between these two species in outbreak cases.
authors.affiliation: Dipartimento di Scienze degli Alimenti, Facoltà di Agraria, Università di Udine, 33100 Udine, Italy. marisa.manzano@uniud.it
authors.forename: Marisa
authors.initials: M
authors.lastname: Manzano
authors.forename: Cristina
authors.initials: C
authors.lastname: Giusto
authors.forename: Lucilla
authors.initials: L
authors.lastname: Iacumin
authors.forename: Carlo
authors.initials: C
authors.lastname: Cantoni
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Comi
mesh_terms: D001409:Bacillus cereus / Q000145:classification* / Q000302:isolation & purification; D001413:Bacillus thuringiensis / Q000145:classification* / Q000302:isolation & purification; D044822:Biodiversity; D027081:DNA Gyrase / Q000235:genetics*; D017931:DNA Primers; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D006801:Humans; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods*; D019105:Random Amplified Polymorphic DNA Technique / Q000379:methods; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D027081:DNA Gyrase