title: The Siderophore Product Ornibactin Is Required for the Bactericidal Activity of Burkholderia contaminans MS14.
abstract: Burkholderia contaminansMS14 was isolated from soil in Mississippi. When it is cultivated on nutrient broth-yeast extract agar, the colonies exhibit bactericidal activity against a wide range of plant-pathogenic bacteria. A bacteriostatic compound with siderophore activity was successfully purified and was determined by nuclear magnetic resonance spectroscopy to be ornibactin. Isolation of the bactericidal compound has not yet been achieved; therefore, the exact nature of the bactericidal compound is still unknown. During an attempt to isolate the bactericidal compound, an interesting relationship between the production of ornibactin and the bactericidal activity of MS14 was characterized. Transposon mutagenesis resulted in two strains that lost bactericidal activity, with insertional mutations in a nonribosomal peptide synthetase (NRPS) gene for ornibactin biosynthesis and aluxRfamily transcriptional regulatory gene. Coculture of these two mutant strains resulted in restoration of the bactericidal activity. Furthermore, the addition of ornibactin to the NRPS mutant restored the bactericidal phenotype. It has been demonstrated that, in MS14, ornibactin has an alternative function, aside from iron sequestration. Comparison of the ornibactin biosynthesis genes inBurkholderiaspecies shows diversity among the regulatory elements, while the gene products for ornibactin synthesis are conserved. This is an interesting observation, given that ornibactin is thought to have the same defined function withinBurkholderiaspecies. Ornibactin is produced by mostBurkholderiaspecies, and its role in regulating the production of secondary metabolites should be investigated.IMPORTANCEIdentification of the antibacterial product from strain MS14 is not the key feature of this study. We present a series of experiments that demonstrate that ornibactin is directly involved in the bactericidal phenotype of MS14. This observation provides evidence for an alternative function for ornibactin, aside from iron sequestration. Ornibactin should be further evaluated for its role in regulating the biosynthesis of secondary metabolites in otherBurkholderiaspecies.
authors.affiliation: Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Deng
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Foxfire
authors.affiliation: Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, USA.|Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Sonya M
authors.initials: SM
authors.lastname: Baird
authors.affiliation: Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Jiayuan
authors.initials: J
authors.lastname: Jia
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA.
authors.forename: Keren H
authors.initials: KH
authors.lastname: Delgado
authors.affiliation: Central Alabama High-Field NMR Facility, Structural Biology Shared Facility, Cancer Center University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Shin
authors.affiliation: Department of Biology, Texas A&M University, College Station, Texas, USA jsmith@bio.tamu.edu sl332@msstate.edu.
authors.forename: Leif
authors.initials: L
authors.lastname: Smith
authors.affiliation: Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, USA jsmith@bio.tamu.edu sl332@msstate.edu.
authors.forename: Shi-En
authors.initials: SE
authors.lastname: Lu
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D000898:Antibiosis; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D019117:Burkholderia / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism; D016296:Mutagenesis; D016254:Mutagenesis, Insertional; D010453:Peptide Synthases / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D017262:Siderophores / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012097:Repressor Proteins; D017262:Siderophores; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins; D007501:Iron; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase
keywords: Burkholderia contaminans MS14; antibacterial activity; ornibactin