Comparative Genomic Hybridization Analysis of Two Predominant Nordic Group I (Proteolytic) Clostridium botulinum Type B Clusters

Abstract

Comparative genomic hybridization analysis of 32 Nordic group I Clostridium botulinum type B strains isolated from various sources revealed two homogeneous clusters, clusters BI and BII. The type B strains differed from reference strain ATCC 3502 by 413 coding sequence (CDS) probes, sharing 88% of all the ATCC 3502 genes represented on the microarray. The two Nordic type B clusters differed from each other by their response to 145 CDS probes related mainly to transport and binding, adaptive mechanisms, fatty acid biosynthesis, the cell membranes, bacteriophages, and transposon-related elements. The most prominent differences between the two clusters were related to resistance to toxic compounds frequently found in the environment, such as arsenic and cadmium, reflecting different adaptive responses in the evolution of the two clusters. Other relatively variable CDS groups were related to surface structures and the gram-positive cell wall, suggesting that the two clusters possess different antigenic properties. All the type B strains carried CDSs putatively related to capsule formation, which may play a role in adaptation to different environmental and clinical niches. Sequencing showed that representative strains of the two type B clusters both carried subtype B2 neurotoxin genes. As many of the type B strains studied have been isolated from foods or associated with botulism, it is expected that the two group I C. botulinum type B clusters present a public health hazard in Nordic countries. Knowing the genetic and physiological markers of these clusters will assist in targeting control measures against these pathogens.Clostridium botulinum produces a potent neurotoxin during its growth. The toxin causes a potentially lethal paralytic disease, botulism, in humans and animals. The classical foodborne botulism follows the consumption of toxin-containing food or drink, while infant and adult intestinal botulism results from in vivo spore germination, outgrowth, and toxin production in the gut. Apart from attenuated intestinal microbial population, other factors affecting the colonization of C. botulinum in the intestinal forms of botulism are not known.Based on their physiology and genetic background, C. botulinum strains are divided into groups I to IV (13). Strains of groups I and II are associated with human disease. Group I strains produce neurotoxin serotypes A, B, and/or F, while the group II strains produce type B, E, or F toxin. Physiologically, groups I and II differ markedly from each other as well as from groups III and IV. Genomic analysis of group I and II C. botulinum strains by 16S rrn sequencing (13), ribotyping (10), and amplified fragment length polymorphism (11,15,16) is consistent with the divergent physiologies of the two groups (18).Nordic C. botulinum group I strains show a remarkable homogeneity (15,20,21,23). In a large pulsed-field gel electrophoresis (PFGE) analysis, the majority of group I strains isolated from various sources from Finland, Norway, and Denmark formed type B neurotoxin and...

Whole-Genome Single-Nucleotide-Polymorphism Analysis for Discrimination of Clostridium botulinum Group I Strains

“…This is similar to what has been observed for all HA ϩ OrfX Ϫ A1 strains; other strains lacking a toxin cluster in this position also lack most of the genes in the ars operon (16). Strains without these arsenic resistance genes are more sensitive to arsenic (31). It is possible that the gain of the HA Ϫ OrfX ϩ BoNT toxin cluster might have occurred using the ars operon as a homologous insertion region.…”

The Cold-Induced Two-Component System CBO0366/CBO0365 Regulates Metabolic Pathways with Novel Roles in Group I Clostridium botulinum ATCC 3502 Cold Tolerance

“…The lack of arsenic resistance-encoding genes in the cluster BI strains was consistent with significantly decreased robustness to the presence of sodium arsenite (47) or low temperature (48). In contrast, the cluster BII strains harboring a full complement of the arsenic resistance machinery showed tolerance to sodium arsenite (47) and to the lower end of the growth temperature range (48), with a 3.3°C lower minimum growth temperature than that of the arsenic-sensitive cluster BI strains. These findings were supported by the impaired or completely abolished growth of the cbo0751 (arsC) and cbo0753 (arsR) mutants, respectively, at 17°C compared to the wild-type strain.…”

“…Furthermore, recombinant CBO0365 was shown to bind to the promoter region of cbo0753 (arsR), suggesting direct transcriptional control the of the ars operon by CBO0365. In our previous studies, an association between arsenic resistance and robustness toward low temperature was observed in C. botulinum (47,48). The Nordic (group I) C. botulinum type B strains form two distinct clusters BI and BII (49,50), which differ in their genomic content and, in particular, in their arsenical resistance operon structure (47).…”

“…In our previous studies, an association between arsenic resistance and robustness toward low temperature was observed in C. botulinum (47,48). The Nordic (group I) C. botulinum type B strains form two distinct clusters BI and BII (49,50), which differ in their genomic content and, in particular, in their arsenical resistance operon structure (47). The lack of arsenic resistance-encoding genes in the cluster BI strains was consistent with significantly decreased robustness to the presence of sodium arsenite (47) or low temperature (48).…”

“…The Nordic (group I) C. botulinum type B strains form two distinct clusters BI and BII (49,50), which differ in their genomic content and, in particular, in their arsenical resistance operon structure (47). The lack of arsenic resistance-encoding genes in the cluster BI strains was consistent with significantly decreased robustness to the presence of sodium arsenite (47) or low temperature (48). In contrast, the cluster BII strains harboring a full complement of the arsenic resistance machinery showed tolerance to sodium arsenite (47) and to the lower end of the growth temperature range (48), with a 3.3°C lower minimum growth temperature than that of the arsenic-sensitive cluster BI strains.…”