Identificación of new lactobacilli able to produce cobalamin (Vitamin B12)

VANNINI, V; F. DE VALDES, G; TARANTO, MP; SESMA, F

Villa Carlos Paz, Córdoba

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Resumen Cobalamin (CBL), a very complex vitamin made by some bacteria and archea, is essential to humans and animals. Recently we have discovered that a strain of Lactobacillus reuteri is able to produce this vitamin. Genomic analysis of some Lb. reuteri strains suggested that the cob genes involved in CBL biosynthesis were acquired by horizontal transfer. The aim of this work was to evaluate the distribution of cob genes and the ability to produce CBL in 16 lactobacilli strains used in the development of a bio-fortified functional food. A biological assay showed that Lb. coryniformis CRL 1001, Lb. curvatus CRL 1000, Lb. murinus CRL1104, and Lb. reuteri CRL 1101, 1324 and 1327 complemented the CBL requirements of the auxotrophic strain, Escherichia coli 113. Higher levels of CBL biosynthesis were observed in the presence of the CBL precursors, dimethylbenzimidazole (DMB) and uroporphyrinogen III. It was shown that some strains harbored the cbiF and hemC genes which show homology with the enzymes Precorrin-4 C11-methyltransferase and Porphobilinogen deaminase respectively, wich are involved in the CBL biosynthetic pathway. Moreover the key gene cobT was amplified by PCR and cloned into the pBluescript vector to perform regulatory studies. The results allow us to conclude that the CBL production is a strain dependent property supporting the horizontal transference hypothesis.