Membrane properties of a plant-pathogenic mycoplasmalike organism.

In terms of biosystematics, the plant-pathogenic mycoplasmalike organisms (MLOs) have been tentatively placed into the class Mollicutes. Certain physiological tests have been used to distinguish families within this class: the sterol-nonrequiring Acholeplasmataceae differ from the sterol-requiring Mycoplasmataceae in that the former are more resistant to lysis by digitonin and more sensitive to lysis in hypotonic salt solutions. To test MLOs for these membrane properties and thus assist in their definitive classification, a dot-blot microassay procedure was used to detect nucleic acids released from lysed cells. The results show that MLOs resemble acholeplasmas grown in the absence of sterols in that they are resistant to digitonin and sensitive to hypotonic salt solutions. The MLOs can be differentiated from acholeplasmas grown without sterols by their greater resistance to lysis in hypotonic sucrose solutions.