A monobromoacetic acid-resistant bacterium, Bacillus strain I37c, was isolated from a marine sediment core. The strain grew in a medium containing 1.8 mg mL(-1) of monobromoacetic acid. It produced constitutively a 2-haloacid dehalogenase that catalyzed the dehalogenation of monobromoacetic acid, monochloroacetic acid, and both L- and D-2-chloropropionic acid. The optimal pH and temperature for the activity measured using a partly purified enzyme were similar to those of known group I haloacid dehalogenases.