Characterization of cold-active dehydrogenases for secondary alcohols and glycerol in psychrotolerant bacteria isolated from Antarctic soil

A NAD(P)+-dependent secondary alcohol dehydrogenase (2°ADH) and a NAD+-dependent glycerol dehydrogenase (GDH) have been identified in a psychrotolerant Micrococcus sp. and Arthrobacter sp., respectively, both isolated from Antarctic soil. In partially purified cell-free extracts (enriched 84- and 78-fold for 2°ADH and GDH, respectively), the enzymes displayed cold activity: the 2°ADH had optimum for activity at 33 °C and retained 32% of its maximum activity at 6 °C, the corresponding values for the GDH were 35 °C and 43%. The enzymes were inactivated within 10 min at 50 and 60 °C, for 2°ADH and GDH, respectively. The 2°ADH was active against a wide range of medium chain-length alcohols, preferring (R)-stereoisomers; the enzyme was reversible with a higher affinity for the reduction of ketones. The GDH was active against glycerol and diols containing a secondary alcohol group. These properties make the enzymes candidates for low temperature biotransformations.