A NAD(P)(+)-dependent secondary alcohol dehydrogenase (2degrees 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 2degrees ADH and GDH, respectively), the enzymes displayed cold activity: the 2degrees ADH had optimum for activity at 33 degreesC and retained 32% of its maximum activity at 6 degreesC, the corresponding values for the GDH were 35 degreesC and 43%. The enzymes were inactivated within 10 min at 50 and 60 degreesC, for 2degrees ADH and GDH, respectively. The 2degrees 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.