Cobalamin production by Lactobacillus coryniformis: biochemical identification of the synthetized corrinoid and genomic analysis of the biosynthetic cluster

CAROLINA TORRES; VERONICA VANINI; BONACINA JULIETA; FONT DE VALDEZ G; SAAVEDRA, LUCILA; TARANTO MP

BMC MICROBIOLOGY

BIOMED CENTRAL LTD

Lugar: Londres; Año: 2016 vol. 16

1471-2180

AbstractBackground: 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 reportedthat certain strains belonging to lactic acid bacteria group are capable of synthesized water-soluble vitamins suchas those included in the B-group, as vitamin B12. In this context, the goal of the present paper was to evaluate andcharacterize the production of vitamin B12 in Lactobacillus coryniformis CRL 1001, a heterofermentative strainisolated from silage.Results: Cell extract of L. coryniformis CRL 1001, isolated from silage, is able to correct the coenzyme B12 requirementof Salmonella enterica serovar Typhimurium AR 2680 in minimal medium. The chemical characterization of thecorrinoid-like molecule isolated from CRL 1001 cell extract using HPLC and mass spectrometry is reported. The majorityof the corrinoid produced by this strain has adenine like Coα-ligand instead 5,6-dimethylbenzimidazole. Genomicstudies revealed the presence of the complete machinery of the anaerobic biosynthesis pathway of coenzyme B12. Thedetected 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 ableto produce pseudocobalamin containing adenine instead of 5,6-dimethlbenzimidazole in the Coα-ligand. Genomicanalysis allowed the identification and characterization of the complete de novo biosynthetic pathway of the corrinoidproduced by the CRL 1001 strain