title: Development of new multilocus variable number of tandem repeat analysis (MLVA) for Listeria innocua and its application in a food processing plant.
abstract: Listeria innocua is an important hygiene indicator bacterium in food industries because it behaves similar to Listeria monocytogenes, which is pathogenic to humans. PFGE is often used to characterize bacterial strains and to track contamination source. However, because PFGE is an expensive, complicated, time-consuming protocol, and poses difficulty in data sharing, development of a new typing method is necessary. MLVA is a technique that identifies bacterial strains on the basis of the number of tandem repeats present in the genome varies depending on the strains. MLVA has gained attention due to its high reproducibility and ease of data sharing. In this study, we developed a MLVA protocol to assess L. innocua and evaluated it by tracking the contamination source of L. innocua in an actual food manufacturing factory by typing the bacterial strains isolated from the factory. Three VNTR regions of the L. innocua genome were chosen for use in the MLVA. The number of repeat units in each VNTR region was calculated based on the results of PCR product analysis using capillary electrophoresis (CE). The calculated number of repetitions was compared with the results of the gene sequence analysis to demonstrate the accuracy of the CE repeat number analysis. The developed technique was evaluated using 60 L. innocua strains isolated from a food factory. These 60 strains were classified into 11 patterns using MLVA. Many of the strains were classified into ST-6, revealing that this MLVA strain type can contaminate each manufacturing process in the factory. The MLVA protocol developed in this study for L. innocua allowed rapid and easy analysis through the use of CE. This technique was found to be very useful in hygiene control in factories because it allowed us to track contamination sources and provided information regarding whether the bacteria were present in the factories.
authors.affiliation: Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Ohshima
authors.affiliation: Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Miku
authors.initials: M
authors.lastname: Nakagawa
authors.affiliation: Department of Food Technology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Krittaporn
authors.initials: K
authors.lastname: Thanatsang
authors.affiliation: Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Chirapiphat
authors.initials: C
authors.lastname: Phraephaisarn
authors.affiliation: Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Yuphakhun
authors.initials: Y
authors.lastname: Chaturongkasumrit
authors.affiliation: Department of Food Technology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Suwimon
authors.initials: S
authors.lastname: Keeratipibul
authors.affiliation: Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuda
authors.affiliation: Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Bon
authors.initials: B
authors.lastname: Kimura
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D019075:Electrophoresis, Capillary; D005511:Food Handling; D005516:Food Microbiology; D008087:Listeria / Q000235:genetics*; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D020080:Tandem Repeat Sequences
chemical_list: D017931:DNA Primers