• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.575-584
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• 2012

Listeria monocytogenes is an important foodborne pathogen that comprises four genetic lineages: I, II, III, and IV. Of these, lineage II is frequently recovered from foods and environments and responsible for the increasing incidence of human listeriosis. In this study, the phylogenetic structure of lineage II was determined through sequencing analysis of the ascB-dapE internalin cluster. Fifteen sequence types proposed by multilocus sequence typing based on nine housekeeping genes were grouped into three distinct sublineages, IIA, IIB, and IIC. Organization of the ascB-dapE internalin cluster could serve as a molecular marker for these sublineages, with inlGHE, inlGC2DE, and inlC2DE for IIA, IIB, and IIC, respectively. These sublineages displayed specific genetic and phenotypic characteristics. IIA and IIC showed a higher frequency of recombination (${\rho}/{\theta}$). However, recombination events had greater effect (r/m) on IIB, leading to its high nucleotide diversity. Moreover, IIA and IIB harbored a wider range of internalin and stress-response genes, and possessed higher nisin tolerance, whereas IIC contained the largest portion of low-virulent strains owing to premature stop codons in inlA. The results of this study indicate that IIA, IIB, and IIC might occupy different ecological niches, and IIB might have a better adaptation to a broad range of environmental niches.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.165-168
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• 2016

Surface protein internalin (InlA) is a major virulence factor of the food-borne pathogen L. monocytogenes. It plays an important role in bacteria crossing the host's barrier by specific interaction with the cell adhesion molecule E-cadherin. Study of this protein will help to find better ways to prevent listeriosis. In this study, a monoclonal antibody against InlA was used to detect InlA. The reaction was label-free and monitored in real time with an oblique-incidence reflectivity-difference (OI-RD) technique. The kinetic constants k_on and k_off and the equilibrium dissociation constant K_d for this reaction were also obtained. These parameters indicate that the antibody is capable of detecting InlA. Additionally, the results also demonstrate the feasibility of using OI-RD for proteomics research and bacteria detection.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2030-2035
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• 2016

Bacillus cereus causes food-borne illness through contaminated foods; therefore, its pathogenicity and genome sequences have been analyzed in several studies. We sequenced and analyzed B. cereus strain FORC_021 isolated from a sashimi restaurant. The genome sequence consists of 5,373,294 bp with 35.36% GC contents, 5,350 predicted CDSs, 42 rRNA genes, and 107 tRNA genes. Based on in silico DNA-DNA hybridization values, B. cereus ATCC $14579^T$ was closest to FORC_021 among the complete genome-sequenced strains. Three major enterotoxins were detected in FORC_021. Comparative genomic analysis of FORC_021 with ATCC $14579^T$ revealed that FORC_021 harbored an additional genomic region encoding virulence factors, such as putative ADP-ribosylating toxin, spore germination protein, internalin, and sortase. Furthermore, in vitro cytotoxicity testing showed that FORC_021 exhibited a high level of cytotoxicity toward INT-407 human epithelial cells. This genomic information of FORC_021 will help us to understand its pathogenesis and assist in managing food contamination.