Diversity of proteolytic Clostridium botulinum strains, determined by a pulsed-field gel electrophoresis approach.
Pulsed-field gel electrophoresis (PFGE) was applied to the study of the similarity of 55 strains of proteolytic Clostridium botulinum (C. botulinum group I) types A, AB, B, and F. Rare-cutting restriction enzymes ApaI, AscI, MluI, NruI, PmeI, RsrII, SacII, SmaI, and XhoI were tested for their suitability for the cleavage of DNA of five proteolytic C. botulinum strains. Of these enzymes, SacII, followed by SmaI and XhoI, produced the most convenient number of fragments for genetic typing and were selected for analysis of the 55 strains. The proteolytic C. botulinum species was found to be heterogeneous. In the majority of cases, PFGE enabled discrimination between individual strains of proteolytic C. botulinum types A and B. The different toxin types were discriminated at an 86% similarity level with both SacII and SmaI and at an 83% similarity level with XhoI. Despite the high heterogeneity, three clusters at a 95% similarity level consisting of more than three strains of different origin were noted. The strains of types A and B showed higher diversity than the type F organisms which formed a single cluster. According to this survey, PFGE is to be considered a useful tool for molecular epidemiological analysis of proteolytic C. botulinum types A and B. However, epidemiological conclusions based on PFGE data only should be made with discretion, since highly similar PFGE patterns were noticed, especially within the type B strains.
Nevas
Mari
M
Department of Food and Environmental Hygiene, Faculty of Veterinary Medicine, University of Helsinki, PO Box 66, 00014 Helsinki University, Finland. mari.nevas@helsinki.fi
Lindström
Miia
M
Hielm
Sebastian
S
Björkroth
K Johanna
KJ
Peck
Michael W
MW
Korkeala
Hannu
H
D015373:Bacterial Typing Techniques; D001905:Botulinum Toxins / Q000145:classification / Q000235:genetics; D003014:Clostridium botulinum / Q000145:classification* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D016521:Electrophoresis, Gel, Pulsed-Field; D014644:Genetic Variation; D017720:Molecular Epidemiology; D010447:Peptide Hydrolases / Q000378:metabolism; D010802:Phylogeny
D004269:DNA, Bacterial; D004262:DNA Restriction Enzymes; D010447:Peptide Hydrolases; D001905:Botulinum Toxins