Metabolic shift in the production of corrinoid compounds by Lactobacillus coryniformis in the absence of purines

TORRES, ANDREA CAROLINA; ELEAN, MARIANO; HEBERT, ELVIRA MARÍA; SAAVEDRA, LUCILA; TARANTO, MARÍA PÍA

BIOCHIMIE

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Año: 2020 vol. 168 p. 185 - 189

0300-9084

Lactobacillus coryniformis CRL 1001 and L. reuteri CRL 1098 have the complete genes necessaryto synthesize pseudo-cobalamin as final product in a vitamin B12 free commercial medium. Unlikevitamin-B12 (the most biologically active form), the pseudo-cobalamin contains adenine instead of5,6-dimethlbenzimidazole (DMB) in the Coα-ligand. Considering the vitamin B12-gene clusters ofthese bacteria, the aim of this work was to analyze the production of corrinoids with DMB (vitaminB12) instead of adenine (pseudo-B12) as lower ligand base in a vitamin B12 free chemically definedmedium (CDM) without purines. Genome-wide screening of genes related to purine metabolismshowed that both strains possess all pur genes necessary for the synthesis of inositolmonophosphate, the main precursor for purine biosynthesis. Accordingly, both strains were able togrow in B12 free CDM without purines, with the supplementation of different syntheticintermediaries. Isolated compounds with positive B12 activity were quantified and characterized byLC/MS-MS. Total corrinoids values were higher for both strains in comparison to those obtained invitamin B12 free commercial medium. Interestingly, CRL 1001 strain synthesized cobalamin,suggesting that this strain is able to activate DMB as nitrogenous base instead adenine when it is inexcess in a purine-free medium. The present paper represents the first demonstration of a partialmetabolic shift to produce vitamin B12 in a Lactobacillus strain.