Figure 7.

Blue-grey phase variation is readily observed in biofilm forming cultures. (A) Western blot analysis of LVS strains was performed on 8 representative colony variants that arose after streaking biofilm positive freezer stocks on chocolate agar. Pellets from purified isolates were lysed and equal concentrations of extracts were separated on SDS-PAGE gels blotted with either α-LPS (left) or α-capsule (right). In each case, α-GroEL was used as a loading control. WT corresponds to the wild-type LVS strain. Numbers correspond to the respective variant isolates. (B) A crystal violet biofilm assay was used to determine the biofilm forming capacity of each of the purified LVS isolates. Red asterisks indicate grey variants as identified by western blotting. Red lines indicate the median.