Despite increasing knowledge and advancements in food preservation techniques, microbial spoilage of foods causes substantial losses with negative social and economic consequences. Brochothrix thermosphacta is one of the most common meat spoilage organisms and is closely related to the food-borne pathogen Listeria monocytogenes. While genome characterisation of L. monocytogenes and other Listeria species has been extensive, until now, genomic analyses have not been conducted of members of the Brochothrix genus.
In this study, 12 B. thermosphacta strains were sequenced and assembled to draft genome status. The genomes of the 12 strains were characterised in detail and a search was conducted for Listeria virulence genes and their remnants present in Brochothrix genomes.
Core- and pan genome analysis revealed a high degree of sequence similarity between the B. thermosphacta strains, with bacteriophage genes overrepresented among non-core genes. Other notable differences include the presence of tetracycline and mercuric resistance genes on mobile genetic elements in individual strains. Genes required for the conversion of pyruvate to malodourous compounds such as acetate, acetoin and butandiol were found as well as lipolytic enzymes and stress response regulatory genes, which likely play an important role in the spoilage process. Furthermore, orthologs of Listeria virulence proteins involved in virulence regulation, intracellular survival and surface protein anchoring were identified in the B. thermosphacta genomes, however, key virulence genes were not found. Collectively, this study not only provides a comprehensive analysis of the B. thermosphacta genome, but it also identifies a number of spoilage-relevant pathways, which may aid in the development of more effective mechanisms of actions in the prevention of food contamination and the spoilage process.