Influence of cultivation media on genetic regulatory patterns in Borrelia burgdorferi

Barbour-Stoenner-Kelly II (BSKII) medium and BSKH medium both are routinely used for the cultivation of Borrelia burgdorferi. However, heretofore ther e have been no studies to compare how these two media affect gene expressio n patterns in virulent B. burgdorferi. In the present study, we found that some B. burgdorferi strain 297 genes (e.g., ospA, mlp-7A, mlp-8, p22, and l p6.6) that typically are regulated by temperature or pH displayed their pre dicted pattern of expression when B. burgdorferi was cultivated in BSKH med ium; this was not true when spirochetes were cultivated in conventional BSK II medium. The results suggest that BSKH medium is superior to BSKII medium for gene expression studies with B. burgdorferi.