Lactobacillus reuteriCRL1098 Produces Cobalamin

Abstract

We found that Lactobacillus reuteri CRL1098, a lactic acid bacterium isolated from sourdough, is able to produce cobalamin. The sugar-glycerol cofermentation in vitamin B 12 -free medium showed that this strain was able to reduce glycerol through a well-known cobalamin-dependent reaction with the formation of 1,3-propanediol as a final product. The cell extract of L. reuteri corrected the coenzyme B 12 requirement of Lactobacillus delbrueckii subsp. lactis ATCC 7830 and allowed the growth of Salmonella enterica serovar Typhimurium (metE cbiB) and Escherichia coli (metE) in minimal medium. Preliminary genetic studies of cobalamin biosynthesis genes from L. reuteri allowed the identification of cob genes which encode the CobA, CbiJ, and CbiK enzymes involved in the cobalamin pathway. The cobamide produced by L. reuteri, isolated in its cyanide form by using reverse-phase high-pressure liquid chromatography, showed a UV-visible spectrum identical to that of standard cyanocobalamin (vitamin B 12 ).

The complete coenzyme B12 biosynthesis gene cluster of Lactobacillus reuteri CRL1098

“…reuteri CRL1098 capable of fulfilling the auxotrophic vitamin B 12 requirements of three different indicator strains (Taranto et al, 2003). In the same study, Lb.…”

“…reuteri's chromosomal DNA with the restriction enzymes BamHI and BglII, using a cysG/hemD (Taranto et al, 2003) probe amplified from the same strain, showed that the signals obtained corresponded to DNA fragments larger than 15 kb for both restriction enzymes (data not shown). Based on this knowledge, two Lb.…”

“…The previously published sequence encoding the fusion protein homologous to CysG/HemD (Taranto et al, 2003) is flanked by the large cluster of 17 cbi genes (Fig. 1).…”

“…Lb. reuteri was the first lactic acid bacterium reported to be able to produce B 12 (Taranto et al, 2003). Increasing our understanding of how this GRAS (generally regarded as safe) organism encodes, acquired and maintains a biosynthetic pathway of such complexity and magnitude is of great importance to the medical field and for the food and feed industries.…”

Structural Characterization of the Active Site of the PduO-Type ATP:Co(I)rrinoid Adenosyltransferase from Lactobacillus reuteri

“…Recently, Lactobacillus reuteri strain CRL1098 was discovered to make B 12 de novo (26), and a gene putatively encoding a homolog of the SePduO enzyme was identified among the cluster of B 12 biosynthetic genes of this bacterium (GenBank TM accession number AY780645). In this study, we report the three-dimensional crystal structure of L. reuteri PduO-type corrinoid adenosyltransferase (LrPduO) complexed with MgATP at 1.68-Å resolution and provide a kinetic characterization of the enzyme.…”