The present invention relates to a nucleic acid molecule, which encodes a polypeptide having alcohol dehydrogenase activity, in particular methanol dehydrogenase activity, comprising having a nucleotide sequence selected from the group consisting of: (i) a nucleotide sequence as set forth in any one of SEQ ID NOs: 1 (mdh2-MGA3), 3 (mdh3-MGA3), or 5 (mdh2-PB1); (ii) a nucleotide sequence having at least 90% sequence identity, more particularly at least 91, 92, 93, 94, 95, 96, 97, 98 or 99% sequence identity, with a nucleotide sequence as set forth in any one of SEQ ID NOs: 1, 3 or 5; (iii) a nucleotide sequence which is degenerate with any one of the nucleotide sequences of SEQ ID NOs: 1, 3 or 5; (iv) a nucleotide sequence which is a part of the nucleotide sequence of any one of SEQ ID NOs: 1, 3 or 5, or of a nucleotide sequence which is degenerate with a sequence of SEQ ID NOs: 1, 3 or 5; (v) a nucleotide sequence encoding all or part of a polypeptide whose amino acid sequence is set forth in any one of SEQ ID NOs: 2 (Mdh2-MGA3), 4 (Mdh3-MGA3) or 6 (Mdh2-PB1); and (vi) a nucleotide sequence encoding all or part of a polypeptide which has an amino acid sequence having at least 90% sequence identity, preferably at least 91, 92, 93, 94, 95, 96, 97, 98 or 99% sequence identity, with an amino acid sequence as set forth in any one of SEQ ID NOs: 2, 4 or 6; or a nucleic acid molecule comprising a nucleotide sequence which is complementary to the nucleotide sequence of any one of (i) to (vi). Also provided are recombinant constructs, vectors and host cells comprising such a nucleic acid molecule and polypeptides encoded thereby. Such molecules may advantageously be used in the genetic modification of host cells, for example to introduce or modify methanol dehydrogenase activity.