FIGURE 6.

Microbial reduction of chlorine oxyanions – a schematic overview. (A) “classical” perchlorate reduction involving a functional chlorite dismutase (Cld, mainly found in mesophilic Proteobacteria), (B) reduction of chlorine oxyanions in the absence of Cld, employing an “intraspecies sulfur loop” (as found in A. fulgidus), (C) potential syntrophic reduction of chlorate and perchlorate, involving interspecies sulfur transfer. Perchlorate-reducing enzymes are depicted in green, chlorite dismutase in red and terminal oxidase in blue. Enzymes involved in the reduction of oxidized sulfur compounds (e.g., S⁰, S₂O₃^2-, S₄O₆^2-, etc.) are shown in yellow.