Whole genome sequencing of Clostridium butyricum that caused the first infant botulism in China

  Objective  To analyze the data obtained from a whole genome sequence of type E botulinum neurotoxin producing Clostridium butyricum TJ-S,which was isolated from stool sample of an infant botulism case for the first time in China.

  Methods  Genomic DNA was extracted from TJ-S isolate, the whole genome sequencing was carried out using Pacific Biosciences RS Ⅱ platform and analyzed.

  Results  One independent closed circle chromosome and one plasmid were found in TJ-S isolate. The lengths of the chromosome and plasmid were 3 949 987 bp and 747 151 bp, GC contents was 28.2% for chromosome and 28.2% for plasmid. The bont/e gene was found in the typical orfX cluster that located on chromosome, and there were three transposase encoding genes on upstream of the cluster. The phylogenetic analysis showed that TJ-S strain and two type E-producing C. butyricum stains which were isolated from infant botulism cases in the United Kingdom were in the same clade.

  Conclusion  The bont/e gene was located in the stable classic orfX cluster of C. butyricum, and it was the main pathogenic gene causing botulism in human. This is the first report of genomic data mining and analysis of type E botulinum neurotoxin producing C. butyricum in China.