show Abstracthide AbstractVitamin B12 (B12) is an important cofactor in mycobacterial metabolism, and some pathogenic mycobacteria need to obtain it from the host. In this study, we investigated the transport of vitamin B12 in Mycobacterium marinum. We identified a transcriptor regulator that could be potentially involved in the uptake process. RNA sequencing analysis were performed in order to elucidate the regulon of this new transcriptor. Overall design: The strain used in the experimen is a metH mutant that is sensitive to vitamin B12 since it relies on MetE (B12 supressed) to produce methionine. It presents a frame-shift mutation for the transcription regulator. The control strain is the metH mutant strain. The resulting mutants were grown on methionine and B12 before RNA extraction. Methonine chemically supplements the absence of MetH. Since the regulator is involved on the B12 uptake, to ensure a higher expression of the gene, we culture the strain with B12. RNA was extracted and transcriptomic analysis was performed.