FIG. 1.

PAGE analysis of phenol-water-extracted material from AK631 and class I mutants (A) and class II, III, and IV mutants (B). K antigen and LPS were visualized via alcian blue-silver staining. The four classes of mutants can be readily distinguished from the parental strain, AK631, by their lack of K antigen. Classes can be distinguished through the properties of their R-LPSs. In class I and class III mutants, the R-LPS is indistinguishable from that of the wild type (note that the lower R-LPS band is absent in the rkp-180 lane due to underloading of the lane). In the class II mutants, the R-LPS separates into the phenol phase during the phenol-water extraction. In the case of the class IV mutants, the R-LPS runs similarly to that of the exoB⁺ parental strain of AK631. WT, wild type; LMW PS, lower-molecular-weight polysaccharide.