Vitamin B12 (cobalamin) synthesis by Lactobacillus coryniformis CRL 1001: biosynthetic pathway and improve production

TORRES, CAROLINA; VANNINI, VERÓNICA; FONT DE VALDEZ, GRACIELA; SAAVEDRA, LUCILA; TARANTO, MARIA PIA

Mar del Plata, Buenos Aires

Congreso; SAIB; 2015

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Cobalamin (CBL) is one of the most complex non-polymeric macromolecules synthesized by Eubacteria and Archaea. The biosynthesis de novo of CBL is highly complex and involves about 30 enzymes.We demonstrated that cell extract of Lactobacillus (L.) coryniformis CRL 1001 is able to correct the coenzyme B12 requirement of Salmonella Typhimurium AR 2680 (metE cbiB) in minimal medium. The aim of this study was analyse the gene cluster encoding for the enzymes involved in the vitamin B12 biosynthesis and establish the CBL biosynthetic pathway used by CRL 1001 strain.In silico analyzes reveal that L. coryniformis CRL 1001 possesses a coenzyme B12 gene cluster encoding the gene sets (cbi, cob, and hem) for CBL biosynthesis. Like the genome of Listeria sp, the CRL 1001 strain genome lack the gene cobT.. In replacements of this gene has 2 cbl genes, cblS and cblT, a α-ribazole or ribosyl kinase and α-ribazole transporter respectively. The cblT and cblS genes are present in CBL-producers Listeria strains and they were found in silico in L. rossiae DSM 15814 but both are absent in L. reuteri CRL1098, the first lactic acid bacterium described as cobalamin producer. To corroborate the genetic findings, we investigated the CBL synthesis by the CRL 1001 strain in the presence of key intermediates: DMB and L-Thr (Threonine) (separately and together). Even though, he addition of DMB increases the corrinoid compound production, the higher concentrations of CBL was obtained in presence of L-Thr. These results provided valuable evidence of the cobalamin synthesis pathway and its regulation in L. coryniformis CRL 1001, a potential probiotic strain.