Impact of Clostridium botulinum genomic diversity on food safety.
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ABSTRACT:
SUBMITTER: Peck MW
PROVIDER: S-EPMC5181784 | biostudies-literature | 2016 Aug
REPOSITORIES: biostudies-literature
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Impact of <i>Clostridium botulinum</i> genomic diversity on food safety.
Peck Michael W MW van Vliet Arnoud Hm AH
Current opinion in food science 20160801
The deadly botulinum neurotoxin formed by <i>Clostridium botulinum</i> is the causative agent of foodborne botulism. The increasing availability of <i>C. botulinum</i> genome sequences is starting to allow the genomic diversity of <i>C. botulinum</i> Groups I and II and their neurotoxins to be characterised. This information will impact on microbiological food safety through improved surveillance and tracing/tracking during outbreaks, and a better characterisation of <i>C. botulinum</i> Groups I ...[more]
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Project description:Botulinum neurotoxins (BoNTs) produced by the bacteria Clostridium botulinum are the causative agent of human and animal botulism, a rare but serious and potentially deadly intoxication. Foodborne botulism is caused by the consumption of foods containing BoNTs, which results from contamination of foods with C. botulinum spores and toxin production by the bacteria during growth within the food. Validation of the safety of food products is essential in preventing foodborne botulism, however, limited guidance and standards exist for the selection of strains used in C. botulinum food challenge studies. Sequencing and genomics studies have revealed that C. botulinum is a large, diverse, and polyphyletic species, with physiologic and growth characteristics studied only in a few representatives. Little is known about potential growth competition or effects on toxin production between C. botulinum strains. In this study, we investigated an applied cocktail of ten C. botulinum strains, seven Group I and three Group II. Whole genome SNP alignments revealed that this strain cocktail encompasses the major clades of the Group I and II C. botulinum species. While growth competition appears to exist between several of the strains, the cocktail as a whole resulted in high levels of BoNT production.
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Project description:The purpose of this study was to determine the level of genomic content similarity among selected strains of Clostridium botuinum type F strains.
2013-12-19 | GSE53456 | GEO
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Project description:Clostridium botulinum is a heterogeneous Gram-positive species that comprises four genetically and physiologically distinct groups of bacteria that share the ability to produce botulinum neurotoxin, the most poisonous toxin known to man, and the causative agent of botulism, a severe disease of humans and animals. We report here the complete genome sequence of a representative of Group I (proteolytic) C. botulinum (strain Hall A, ATCC 3502). The genome consists of a chromosome (3,886,916 bp) and a plasmid (16,344 bp) which carry 3,650 and 19 predicted genes, respectively. Consistent with the proteolytic phenotype of this strain, the genome harbours a large number of genes encoding secreted proteases and enzymes involved in uptake and metabolism of amino acids. The genome also reveals a hitherto unknown ability of C. botulinum to degrade chitin. There is a significant lack of recently acquired DNA, indicating a stable genomic content, in strong contrast to the fluid genome of C. difficile, which can form longer-term relationships with its host. Overall, the genome indicates that C. botulinum is adapted to a saprophytic lifestyle both in soil and aquatic environments. This pathogen relies on its toxin to rapidly kill a wide range of prey species, and to gain access to nutrient sources, it releases a large number of extracellular enzymes to soften and destroy rotting or decayed tissues.
2007-05-23 | E-TABM-264 | biostudies-arrayexpress
Project description:BackgroundType A1 Clostridium botulinum strains are a group of Gram-positive, spore-forming anaerobic bacteria that produce a genetically, biochemically, and biophysically indistinguishable 150 kD protein that causes botulism. The genomes of three type A1 C. botulinum strains have been sequenced and show a high degree of synteny. The purpose of this study was to characterize differences among these genomes and compare these differentiating features with two additional unsequenced strains used in previous studies.ResultsSeveral strategies were deployed in this report. First, University of Massachusetts Dartmouth laboratory Hall strain (UMASS strain) neurotoxin gene was amplified by PCR and sequenced; its sequence was aligned with the published ATCC 3502 Sanger Institute Hall strain and Allergan Hall strain neurotoxin gene regions. Sequence alignment showed that there was a synonymous single nucleotide polymorphism (SNP) in the region encoding the heavy chain between Allergan strain and ATCC 3502 and UMASS strains. Second, comparative genomic hybridization (CGH) demonstrated that the UMASS strain and a strain expected to be derived from ATCC 3502 in the Centers for Disease Control and Prevention (CDC) laboratory (ATCC 3502*) differed in gene content compared to the ATCC 3502 genome sequence published by the Sanger Institute. Third, alignment of the three sequenced C. botulinum type A1 strain genomes revealed the presence of four comparable blocks. Strains ATCC 3502 and ATCC 19397 share the same genome organization, while the organization of the blocks in strain Hall were switched. Lastly, PCR was designed to identify UMASS and ATCC 3502* strain genome organizations. The PCR results indicated that UMASS strain belonged to Hall type and ATCC 3502* strain was identical to ATCC 3502 (Sanger Institute) type.ConclusionsTaken together, C. botulinum type A1 strains including Sanger Institute ATCC 3502, ATCC 3502*, ATCC 19397, Hall, Allergan, and UMASS strains demonstrate differences at the level of the neurotoxin gene sequence, in gene content, and in genome arrangement.
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Project description:BackgroundClostridium botulinum is a group of four physiologically and phylogenetically distinct bacteria that produce botulinum neurotoxin. While studies have characterised variability between strains of Group I (proteolytic) C. botulinum, the genetic and physiological variability and relationships between strains within Group II (non-proteolytic) C. botulinum are not well understood. In this study the genome of Group II strain C. botulinum Eklund 17B (NRP) was sequenced and used to construct a whole genome DNA microarray. This was used in a comparative genomic indexing study to compare the relatedness of 43 strains of Group II C. botulinum (14 type B, 24 type E and 5 type F). These results were compared with characteristics determined from physiological tests.ResultsWhole genome indexing showed that strains of Group II C. botulinum isolated from a wide variety of environments over more than 75 years clustered together indicating the genetic background of Group II C. botulinum is stable. Further analysis showed that strains forming type B or type F toxin are closely related with only toxin cluster genes targets being unique to either type. Strains producing type E toxin formed a separate subset. Carbohydrate fermentation tests supported the observation that type B and F strains form a separate subset to type E strains. All the type F strains and most of type B strains produced acid from amylopectin, amylose and glycogen whereas type E strains did not. However, these two subsets did not differ strongly in minimum growth temperature or maximum NaCl concentration for growth. No relationship was found between tellurite resistance and toxin type despite all the tested type B and type F strains carrying tehB, while the sequence was absent or diverged in all type E strains.ConclusionsAlthough Group II C. botulinum form a tight genetic group, genomic and physiological analysis indicates there are two distinct subsets within this group. All type B strains and type F strains are in one subset and all type E strains in the other.
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Project description:The purpose of this study was to determine the level of genomic content similarity among selected strains of Clostridium botuinum type F strains. In this study, strains were selected that had already been chacaterized by botulinum neurotoxin gene sequencing. Strains harboring bont/F1, bont/F4 and bont/F5 were compared.
2013-12-19 | E-GEOD-53456 | biostudies-arrayexpress
Project description:The PFGRC has developed a cost effective alternative to complete genome sequencing in order to study the genetic differences between closely related species and/or strains. The comparative genomics approach combines Gene Discovery (GD) and Comparative Genomic Hybridization (CGH) techniques, resulting in the design and production of species microarrays that represent the diversity of a species beyond just the sequenced reference strain(s) used in the initial microarray design. These species arrays may then be used to interrogate hundreds of closely related strains in order to further unravel their evolutionary relationships. Clostridium botulinum produces botulinum neurotoxin (BoNT)and is classified as a “Category A” select agent. BoNT can be classified into seven serotypes designated A-G. There is considerable genetic variation within these serotypes, as demonstrated by the recognition of at least 47 subtypes. The most studied serotype, BoNT/A, has been found in a large and diverse group of clostridia, most of which express the subtype BoNT/A1. The BoNT/A1 producing C. botulinum strain ATCC 3502, used to obtain an initial annotated genome sequence, is not representative of the diverse clostridia group producing BoNT. Nearly 50% of C. botulinum strains producing BoNT/A1 have been shown to also encode unexpressed variants of BoNT/B with a distinct cluster arrangement. This nucleotide cluster is completely absent from the published genome sequence. In addition, a recently identified novel BoNT/A1 strain lacks the gene cluster seen in the genome sequence of ATCC 3502. Furthermore, a strain designated Hall A Hyper differs greatly from the sequenced strain as indicated by its ability to produce higher quantities of BoNT/A1. The genetic and phenotypic basis for this difference in BoNT expression is currently unknown, and the sequences of the BoNT gene and the cluster are identical in both strains. This observation supports the hypothesis that genes outside the toxin cluster are involved in the regulation and maturation of BoNT. The flow of genetic information within this group motivated us to identify novel genes for the purpose of creating a “species” DNA microarray to better understand the ancestral relationships among its members. Based on preliminary genotyping (MLST, and CGH using a single-genome-based array), 20 diverse C. botulinum strains were selected for sequencing. Sequence information obtained from this project, and from other publicly available sources, led to the development of a comprehensive species microarray for C. botulinum group members. The availability of the C. botulinum species DNA microarray has allowed us to carry out a collaborative CGH genotyping project to validate this microarray as well as understand the phylogenomic relationships among members of C. botulinum group.
2009-11-26 | GSE19107 | GEO
Project description:Genomic DNA of 61 strains of proteolytic Clostridium botulinum or Clostridium sporogenes was subjected to analysis by DNA microarray.
2008-12-31 | E-MEXP-1637 | biostudies-arrayexpress
Project description:BackgroundClostridium botulinum produces seven distinct serotypes of botulinum neurotoxins (BoNTs). The genes encoding different subtype neurotoxins of serotypes A, B, F and several dual neurotoxin-producing strains have been shown to reside on plasmids, suggesting that intra- and interspecies transfer of BoNT-encoding plasmids may occur. The objective of the present study was to determine whether these C. botulinum BoNT-encoding plasmids are conjugative.Methodology/principal findingsC. botulinum BoNT-encoding plasmids pBotCDC-A3 (strain CDC-A3), pCLJ (strain 657Ba) and pCLL (strain Eklund 17B) were tagged with the erythromycin resistance marker (Erm) using the ClosTron mutagenesis system by inserting a group II intron into the neurotoxin genes carried on these plasmids. Transfer of the tagged plasmids from the donor strains CDC-A3, 657Ba and Eklund 17B to tetracycline-resistant recipient C. botulinum strains was evaluated in mating experiments. Erythromycin and tetracycline resistant transconjugants were isolated from donor:recipient mating pairs tested. Transfer of the plasmids to the transconjugants was confirmed by pulsed-field gel electrophoresis (PFGE) and Southern hybridizations. Transfer required cell-to-cell contact and was DNase resistant. This indicates that transfer of these plasmids occurs via a conjugation mechanism.Conclusions/significanceThis is the first evidence supporting conjugal transfer of native botulinum neurotoxin-encoding plasmids in C. botulinum, and provides a probable mechanism for the lateral distribution of BoNT-encoding plasmids to other C. botulinum strains. The potential transfer of C. botulinum BoNT-encoding plasmids to other bacterial hosts in the environment or within the human intestine is of great concern for human pathogenicity and necessitates further characterization of these plasmids.
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