Characterisation of an l-Haloacid Dehalogenase from the Marine Psychrophile Psychromonas ingrahamii with Potential Industrial Application

The recombinant l-haloacid dehalogenase from the marine bacterium Psychromonas ingrahamii has been cloned and over-expressed in Escherichia coli. It shows activity towards monobromoacetic (100 %), monochloroacetic acid (62 %), S-chloropropionic acid (42 %), S-bromopropionic acid (31 %), dichloroacetic acid (28 %) and 2-chlorobutyric acid (10 %), respectively. The l-haloacid dehalogenase has highest activity towards substrates with shorter carbon chain lengths (≤C3), without preference towards a chlorine or bromine at the α-carbon position. Despite being isolated from a psychrophilic bacterium, the enzyme has mesophilic properties with an optimal temperature for activity of 45 °C. It retains above 70 % of its activity after being incubated at 65 °C for 90 min before being assayed at 25 °C. The enzyme is relatively stable in organic solvents as demonstrated by activity and thermal shift analysis. The V _max and K _m were calculated to be 0.6 μM min^?1 mg^?1 and 1.36 mM with monobromoacetic acid, respectively. This solvent-resistant and stable l-haloacid dehalogenase from P. ingrahamii has potential to be used as a biocatalyst in industrial processes.