A PATTERN OF EVOLUTION IN THE GENUS ACETOBACTER

The facile mutation, recorded in a previous communication, whereby Acetobacter mesoxydans gave rise to “mutants” or “variants” indistinguishable from, respectively, A. xylinum and A. rancens, and to a number of less positively identifiable strains, has prompted a further search for similar evidence of mutation in other Acetobacter species. It has now been found that, with the exception of A. lovaniense N.C.I.B. 8620, and A. suboxydans N.C.I.B. 3734, all the strains studied already contained “morphological mutants,” some of which gave rise, under laboratory cultivation, to further mutants still more diverse in form and characteristics. From these and the previous results, a pattern of evolution in Acetobacter seems to emerge; it appears that there may be only one species of Acetobacter, or perhaps two, and that the numerous ones described in the literature are but mutants of one or two parent types. The implication of Leifson's work that the members of the suboxydans group are of different phylogenetic origin, and should not be included in Acetobacter, is accepted, such species being considered separately, and not being included in the evolutionary pattern suggested for Acetobacter proper.