Résumé:
It is now clearly established that vitamin B12 (cobalamin) plays an important role in the
cognitive functions efficiency. To understand how the gut microbiota protects cobalamin deficiency in
the central nervous system, we propose probiotic intake as a solution to neurological deficits related to
this vitamin. In this work, we continued the identification of bacteria isolated by Abbassa and
Moussa (2018) recognized for their good production of cobalamin. The identification focused on the
Gram and the physicochemical characteristics, as well as the fermentation of the different sugars to
identify the bacterial species. The in vivo study (not performed) on mice (CD320 KO: genetically
modified carrying a gene deficiency encoding the B12 receptor; compared to strains of wild mice)
describes the multi-T aquatic Labyrinthe and the open field tests highlighting the neuro-functional role
of vitamin B12 . Our macroscopic identification results indicate that all isolates give round, whitish
colonies with a smooth appearance, their size is approximately 1 to 2 mm in diameter.
Microscopically, the Gram is positive. The catalase and negative oxidase isolates were inoculated on
the Api 20A galleries and the fermentation profile examined on the Biomérieux website assumed that
the isolates of SL1 to SL10 belonged to the species L. fermentum, and the isolates SS1, SS2 and SS10
to the species L. brevis based on the esculin test. In the in vivo study and in accordance with the
behavioral deficits, the knockout model shows a decrease in behavioral expression. His results showed
that KO mice (deficient in B12 in the brain) had a longer labyrinth exit latency compared to control
WT mice. Using an open field test, Mimoun (2017) showed that KO mice essentially exhibited a
lower stress level since they spent, significantly, a less time staying in unprotected areas compared to
control WT mice. The study of the CD320 KO mouse model could provide a better understanding of
the effects of vitamin B12 deficiency observed in humans. Palliative treatment based on probiotic
intake could probably identify potential responses to various associated neurological disorders.
