title: Fatty acid production from amino acids and alpha-keto acids by Brevibacterium linens BL2.
abstract: Low concentrations of branched-chain fatty acids, such as isobutyric and isovaleric acids, develop during the ripening of hard cheeses and contribute to the beneficial flavor profile. Catabolism of amino acids, such as branched-chain amino acids, by bacteria via aminotransferase reactions and alpha-keto acids is one mechanism to generate these flavorful compounds; however, metabolism of alpha-keto acids to flavor-associated compounds is controversial. The objective of this study was to determine the ability of Brevibacterium linens BL2 to produce fatty acids from amino acids and alpha-keto acids and determine the occurrence of the likely genes in the draft genome sequence. BL2 catabolized amino acids to fatty acids only under carbohydrate starvation conditions. The primary fatty acid end products from leucine were isovaleric acid, acetic acid, and propionic acid. In contrast, logarithmic-phase cells of BL2 produced fatty acids from alpha-keto acids only. BL2 also converted alpha-keto acids to branched-chain fatty acids after carbohydrate starvation was achieved. At least 100 genes are potentially involved in five different metabolic pathways. The genome of B. linens ATCC 9174 contained these genes for production and degradation of fatty acids. These data indicate that brevibacteria have the ability to produce fatty acids from amino and alpha-keto acids and that carbon metabolism is important in regulating this event.
authors.affiliation: Center for Integrated BioSystems, Utah State University, Logan, Utah 84322-4700, USA.
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Ganesan
authors.forename: Kimberly
authors.initials: K
authors.lastname: Seefeldt
authors.forename: Bart C
authors.initials: BC
authors.lastname: Weimer
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000597:Amino Acids, Branched-Chain; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001951:Brevibacterium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D050260:Carbohydrate Metabolism; D003470:Culture Media; D005227:Fatty Acids / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006863:Hydrogen-Ion Concentration; D007651:Keto Acids / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D001426:Bacterial Proteins; D003470:Culture Media; D005227:Fatty Acids; D007651:Keto Acids; D012965:Sodium Chloride