Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

Taxonomic Identification of Bacillus Species Using Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2016 December, Volume 19, Issue 4, pages 110-120.

https://doi.org/10.5145/ACM.2016.19.4.110

Taxonomic Identification of Bacillus Species Using Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry

Won Seon Yu, Kyeong Min Lee, Kyu Jam Hwang

Pathogen Resource TF, Center for Infectious Diseases, Korea National Institute of Health, Korea Centers for Disease Control and Prevention, Cheongju, Korea

Abstract

Background: In this study, we compared various methods of taxonomic identification of Bacillus strains: biochemical methods, 16S rRNA gene sequencing, and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). We also developed a pathogen- isolate resource database, thus increasing the identification rate when using MALDI-TOF MS.

Methods: Thirty Bacillus strains were obtained from the NCCP (National Culture Collection for Pathogens) and were identified using the VITEK 2 system (bioMérieux, France), API kit (bioMérieux, France), 16S rRNA gene sequencing, and MALDI-TOF MS. The pathogenicity of Bacillus cereus was confirmed through the identification of virulent genes using a multiplex PCR, and both protein extraction for protein profiling in MALDI-TOF MS and repetitive-sequence fingerprinting were performed.

Results: The identification rates at the species level were 40%, 80%, and 76.3% for the VITEK 2 system (bioMérieux), 16S rRNA gene sequencing, and MALDI- TOF MS, respectively. When the major spectrum- profiling dendrogram was compared with the phylogenetic tree, which was constructed based on the 16S rRNA gene sequences and rep-PCR fingerprinting, the classifications were confirmed to be effective.

Conclusion: Identification of Bacillus strains using MALDI-TOF MS was more effective than that using the VITEK 2 system (bioMérieux), but was similar to that using 16S rRNA gene sequencing. Continual addition to a proteome-based database can result in increased identification rates for MALDI-TOF MS. (Ann Clin Microbiol 2016;19:110-120)

Keywords

Bacillus speciess, Identification, MALDI- TOF MS