Filipe Branco dos Santos, B. Teusink, W. M. D. Vos
Jul 13, 2009
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0
Influential Citations
2
Citations
Journal
Journal of Applied Microbiology
Abstract
Sir, In vitro studies have shown that the binding affinity of pseudovitamin B12 to intrinsic factor, a protein required for the absorption of vitamin B12 in mammals, is 500-fold lower than for cobalamin (Stupperich and Nexo 1991). Nevertheless, in vivo studies evaluating the efficiency of pseudovitamin B12 in correcting vitamin B12 deficiency remain to be carried out (Santos et al. 2007). These would be highly relevant from a scientific and biotechnological point of view, as stated recently in the Journal of Applied Microbiology (Molina et al. 2009). Contrary to what is suggested by Molina et al. (2009), we argue that the evidence presented in their study does not support that pseudovitamin B12 is biologically active in mice. In this study, the authors cultivate Lactobacillus reuteri in De Man, Rogosa, Sharpe (MRS) broth, a medium containing vitamin B12 (Chervaux et al. 2000). Under such conditions, de novo synthesis of pseudovitamin B12 is inhibited by a negative feedback regulatory mechanism by vitamin B12 itself (Santos et al. 2008), and L. reuteri will meet its B12-requirements by sequestering cobalamin from the environment, as described for many other organisms (Rodionov et al. 2003). This leads to a radically different explanation for their observations, which Molina et al. did not discuss in their paper. More likely than delivering pseudovitamin B12, L. reuteri is simply carrying over vitamin B12 freely available in MRS, which is then freed when (some) cells lyse either during suspension in water or during the passage through the digestive tract of the mice. It is our conviction that in order to demonstrate that the corrinoid produced by L. reuteri CRL1098 is a suitable source of vitamin B12 for mammals, at least the following criteria should be met: (i) L. reuteri should be cultured in B12-free medium as described previously (Santos et al. 2007); (ii) the identity of the corrinoid produced should be confirmed as pseudovitamin B12 and (iii) additionally, the purified pseudovitamin B12 should also be used independently to complement the vitamin B12-free diet. F. Santos, B. Teusink, W.M. de Vos and J. Hugenholtz 1 Center for Integrative Bioinformatics (IBIVU), Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands 2 Kluyver Centre for Genomics of Industrial Fermentation, NCSB, Julianalaan 67, 2628 BC Delft, The Netherlands. 3 Laboratory of Microbiology, Wageningen University and Research Centre, Dreijenplein 10, 6703 HB Wageningen, The Netherlands 4 TI Food and Nutrition, and NIZO food research, Kernhemseweg 2, PO Box 20, 6710 BA Ede, The Netherlands