Listeria thailandensis sp. nov

Area of Science:

• Microbiology
• Bacteriology
• Food Safety

Background:

• Listeria species are significant foodborne pathogens.
• Ongoing surveillance is crucial for identifying novel bacterial strains in food products.

Purpose of the Study:

• To characterize and classify a previously unknown bacterium isolated from food samples in Thailand.
• To determine if the isolate represents a new species within the Listeria genus.

Main Methods:

• Phylogenetic analysis using 16S rRNA gene and core Listeria genes.
• Whole-genome sequence analyses including average nucleotide blast identity (ANI), pairwise amino acid identity (AAI), and percentage of conserved proteins (POCP).
• Phenotypic characterization, including acid production from various carbohydrates.

Main Results:

• The novel bacterium could not be assigned to any known Listeria species.
• Phylogenetic and genomic analyses confirmed it as a new taxon within the Listeria genus, closely related to L. aquatica, L. floridensis, L. fleishmannii, and L. costaricensis.
• Phenotypic tests revealed unique acid production from d-tagatose and inositol compared to other Listeria species.

Conclusions:

• A new bacterial species, Listeria thailandensis sp. nov., is proposed.
• The type strain CLIP 2015/00305T represents this novel species.
• This finding expands the known diversity of the Listeria genus and highlights the importance of food surveillance.