protein by these genes is involucre to abate the oxidative stress provoked by heavy
metal nonessentials. The presence of thioredoxin codified by chrA gene has been
reported in enzymatic chromium reduction processes. The capacity to reduce U
Fig. 13.11 Phylogenetic tree for the sequence obtained of cadA gene. The analysis was carried out
with 550 aligned amino acids with related sequence to species that exhibit resistance to cadmium.
The tree was built using a maximum likelihood algorithm. The scale bar represents 50 nucleotide
substitutions per 100 amino acid. Bootstrap values, expressed as a percentage of 1000 repetitions,
are shown at branching points. Only values greater than 50% are displayed
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M. I. Neria-González and R. Aguilar-López