ENRICHMENT AND ISOLATION OF A REDUCTIVELY DEBROMINATING BACTERIUM FROM THE BURROW OF A BROMOMETABOLITE-PRODUCING MARINE HEMICHORDATE

An anaerobic 2,4,6-tribromophenol debrominating bacterium, strain DSL-1, was isolated from enrichment cultures inoculated with sediment from the burrows of the bromoaromatic-producing marine hemichordates Balanoglossus aurantiacus and Saccoglossus kowalewskyi. DSL-1 preferentially removed ortho-position bromines, resulting in the transient appearance of 2,4-dibromophenol and accumulation of 4-bromophenol. Cell-free extracts and partially purified reductive debrominase preparations from DSL-1 also debrominated 2,4,6-tribromophenol, yielding 2,4-dibromophenol and 4-bromophenol. Both NADH and NADPH stimulated 2,4,6-tribromophenol reduction by partially purified debrominase. These data are consistent with a reductive debromination mechanism. The organic cosubstrate(s) and specific electron donors used by DSL-1 in vivo are currently unknown.