The influence of cholesterol, progesterone, 4-androstenedione and testosterone on the growth of Treponema denticola ATCC 33520 in batch cultures

Previously, we have shown that reference and freshly isolated Treponema denticola cultures are capable of metabolising cholesterol, progesterone, 4-androstenedione and testosterone by means of 5α-reductase, 3β-and 17β-hydroxysteroid dehydrogenase activity [Clark DT, Soory M. The metabolism of cholesterol and certain hormonal steroids by Treponema denticola. Steroids. 2006;71:352–63. [10]]. The aim of the work presented in this paper was to investigate the modulation of T. denticola growth in batch cultures by these steroids, using T. denticola ATCC 33520 as a model system. Growth curves were summarised using statistics based on optical density and protein yield. Cholesterol was found to stimulate growth at concentrations of 10 and 25 μg/mL. Certain hormonal steroids inhibited the maximum achievable optical density at concentrations of 1 and 10 μg/mL while the minimum concentration shown to inhibit protein yield was 0.001 μg/mL of progesterone. The potential of the hormonal steroids to inhibit growth was in the order of progesterone, 4-androstenedione and testosterone.