FIG. 6.

Microcolonies of different strains of B. burgdorferi on matrices of intact collagen. B. burgdorferi strains were cultured on type I intact collagen matrices for as long as 14 days in the presence of BSK-H medium with and without rabbit serum. Fluorescence microscopy photographs of the five strains are shown. After 14 days, all the Borrelia strains (except MC-1) were actively motile, and MC-1 was alive, as demonstrated by staining with the LIVE/DEAD Bac Light Viability kit. Strain MC-1 grew better in medium lacking rabbit serum.