title: Cobalamin production by Lactobacillus coryniformis: biochemical identification of the synthetized corrinoid and genomic analysis of the biosynthetic cluster.
abstract: BACKGROUND
  Despite the fact that most vitamins are present in a variety of foods, malnutrition, unbalanced diets or insufficient intake of foods are still the cause of vitamin deficiencies in humans in some countries. Vitamin B12(Cobalamin) is a complex compound that is only naturally produced by bacteria and archea. It has been reported that certain strains belonging to lactic acid bacteria group are capable of synthesized water-soluble vitamins such as those included in the B-group, as vitamin B12. In this context, the goal of the present paper was to evaluate and characterize the production of vitamin B12in Lactobacillus coryniformis CRL 1001, a heterofermentative strain isolated from silage.
  
  
  RESULTS
  Cell extract of L. coryniformis CRL 1001, isolated from silage, is able to correct the coenzyme B12requirement of Salmonella enterica serovar Typhimurium AR 2680 in minimal medium. The chemical characterization of the corrinoid-like molecule isolated from CRL 1001 cell extract using HPLC and mass spectrometry is reported. The majority of the corrinoid produced by this strain has adenine like Coα-ligand instead 5,6-dimethylbenzimidazole. Genomic studies revealed the presence of the complete machinery of the anaerobic biosynthesis pathway of coenzyme B12. The detected genes encode all proteins for the corrin ring biosynthesis and for the binding of upper (β) and lower (α) ligands in one continuous stretch of the chromosome.
  
  
  CONCLUSIONS
  The results here described show for the first time that L. coryniformis subsp. coryniformis CRL 1001 is able to produce pseudocobalamin containing adenine instead of 5,6-dimethlbenzimidazole in the Coα-ligand. Genomic analysis allowed the identification and characterization of the complete de novo biosynthetic pathway of the corrinoid produced by the CRL 1001 strain.
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: Andrea Carolina
authors.initials: AC
authors.lastname: Torres
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: Verónica
authors.initials: V
authors.lastname: Vannini
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: Julieta
authors.initials: J
authors.lastname: Bonacina
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: Graciela
authors.initials: G
authors.lastname: Font
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina.
authors.forename: Lucila
authors.initials: L
authors.lastname: Saavedra
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Tucumán, Argentina. ptaranto@cerela.org.ar.
authors.forename: María Pía
authors.initials: MP
authors.lastname: Taranto
mesh_terms: D000225:Adenine / Q000378:metabolism; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001562:Benzimidazoles / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003038:Cobamides / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D007778:Lactobacillus / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D005810:Multigene Family; D016366:Open Reading Frames; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics; D020539:Sequence Analysis, Protein; D012820:Silage / Q000382:microbiology; D014805:Vitamin B 12 / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D001562:Benzimidazoles; D003038:Cobamides; C015158:5,6-dimethylbenzimidazole; C000913:cobamamide; D000225:Adenine; D014805:Vitamin B 12
keywords: Cobalamin production; Coenzyme B12 gene cluster organization; Lactobacillus