Growth parameters of Borrelia burgdorferi sensu stricto at various temperatures.

Growth of Borrelia burgdorferi sensu stricto (prototype strain B-31) was studied in Barbour-Stoenner-Kelly BSK-H liquid medium, supplemented with 4.5% rabbit serum and antibiotics (phosphomycin, rifampicin), at various temperatures to early stationary growth phase. The number of cells was determined by darkfield microscopy. In the range of cultivation temperatures of 25 degrees C to 37 degrees C, generation time was between 8.26 and 12.36 h (the shortest one at 33 degrees C), and the specific growth rate between 0.056 and 0.083 h-1 (the highest one at 33 degrees C). The optimum growth temperature for B. burgdorferi was 33 degrees C, although good growth was also observed at 28 degrees C, 30 degrees C, 35 degrees C and 37 degrees C. The strain grew well but slowly at the temperature of 25 degrees C, whereas no growth was observed at 20 degrees C.