Since the early ages, human beings have used colored materials to leave marks on their environment and the following generations. In time, paints, which gained great importance with painting the objects and the items they used, brought environmental problems with them. Synthetic paints/dyes used to meet the increasing need over time had to be eliminated from the environment. Nowadays, using bacteria is considered as a good solution for eliminating dyes that contain azo groups. These dyes are

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... d in large quantities and difficult to decompose. The main goal of this study was to decolor six different (amido black 10B, evans blue, janus green, methyl orange, methyl red, and orange G) azo dyes by use of four different psychrotolerant Bacillus (Bacillus sp, B. cereus, B. mycoides, and B. subtilis) isolates. According to the obtained results, it was determined that the psychrotolerant Bacillus isolates could remove colors of the six azo dyes by presenting high decolorization activity (up to 98%).