FIG. 4.

Maximum-likelihood tree of deduced amino acid sequences of mxaF genes amplified from the ¹³C-DNA fraction (•). The tree was constructed with a filter (171 aligned amino acid positions; this excludes ambiguities and missing data), with the amino acid sequence of the structurally related ethanol dehydrogenase of Pseudomonas aeruginosa (26) as an outgroup. Multifurcations indicate branch points where the topology between maximum-likelihood, evolutionary-distance, and maximum-parsimony analyses of the data set were not supported by a strict consensus rule.