title: Insight into the Genome of Brochothrix thermosphacta, a Problematic Meat Spoilage Bacterium.
abstract: Brochothrix thermosphactais a dominant but poorly studied meat spoilage organism. It is a close relative of the foodborne pathogenListeria monocytogenes, andBrochothrixconstitutes the second genus in theListeriaceaefamily. Here, the genomes of 12B. thermosphactastrains were sequenced, assembled into draft genomes, characterized, and compared with the genomes ofBrochothrix campestrisandL. monocytogenesPhenotypic properties including biogenic amine production and antibiotic and heavy metal susceptibilities were tested. Comparative genomic analyses revealed a high degree of similarity among theB. thermosphactastrains, with bacteriophage genes constituting a significant proportion of the accessory genome. Genes for the production of the malodorous compounds acetate, acetoin, butanediol, and fatty acids were found, as were stress response regulatory genes, which likely play important roles in the spoilage process. Amino acid decarboxylases were not identified in the genomes, and phenotypic testing confirmed their absence. Orthologs ofListeriavirulence proteins involved in virulence regulation, intracellular survival, and surface protein anchoring were found; however, key virulence genes were absent. Analysis of antibiotic susceptibility showed that strains were sensitive to the four tested antibiotics, except for one tetracycline-resistant isolate with plasmid-mediated tetracycline resistance genes. Strains tolerated higher levels of copper and cobalt than of cadmium although not at concentrations high enough to categorize the strains as being resistant. This study provides insight into theBrochothrixgenome, links previous phenotypic data and data provided here to the gene inventory, and identifies genes that may contribute to the persistence of this organism in the food chain.IMPORTANCEDespite increasing knowledge and advances in food preservation techniques, microbial spoilage of foods causes substantial losses, with negative social and economic consequences. To better control the contamination and microbial spoilage of foods, fundamental knowledge of the biology of key spoilage bacteria is crucial. As a common meat spoilage organism,B. thermosphactacontributes substantially to spoilage-associated losses. Nonetheless, this organism and particularly its genome remain largely unstudied. This study contributes to improving our knowledge of theBrochothrixgenus. Spoilage-relevant pathways and genes that may play a role in the survival of this organism in a food processing environment were identified, linking previous phenotypic data and data provided here to the gene inventory ofBrochothrixand establishing parallels to and differences from the closely related foodborne pathogenL. monocytogenes.
authors.affiliation: CSIRO Agriculture and Food, Werribee, Victoria, Australia Tamsyn.Stanborough@csiro.au.|Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Tamsyn
authors.identifier: http://orcid.org/0000-0001-5945-2536
authors.initials: T
authors.lastname: Stanborough
authors.affiliation: CSIRO Agriculture and Food, Werribee, Victoria, Australia.
authors.forename: Narelle
authors.initials: N
authors.lastname: Fegan
authors.affiliation: Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Shane M
authors.initials: SM
authors.lastname: Powell
authors.affiliation: Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Tamplin
authors.affiliation: CSIRO Agriculture and Food, Werribee, Victoria, Australia.
authors.forename: P Scott
authors.initials: PS
authors.lastname: Chandry
mesh_terms: D000588:Amines / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001435:Bacteriophages / Q000235:genetics; D058640:Brochothrix / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000821:virology; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling; D005516:Food Microbiology; D018857:Food Packaging; D005519:Food Preservation / Q000379:methods; D005517:Foodborne Diseases / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D019450:Genes, MDR / Q000235:genetics; D016680:Genome, Bacterial; D008089:Listeria monocytogenes / Q000235:genetics; D008460:Meat / Q000382:microbiology*; D019216:Metals, Heavy / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological / Q000235:genetics; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000588:Amines; D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D019216:Metals, Heavy; D037521:Virulence Factors
keywords: Brochothrix; Listeria monocytogenes; meat spoilage; spoilage