Effect of 7β‐hydroxycholesterol on growth and membrane composition of <i>Mycoplasma capricolum</i>

7β‐OH cholesterol in a cholesterol rich growth medium (5–10 μg/ml) extended the lag period and slowed down the growth rate of Mycoplasma capricolum cells. In a cholesterol poor medium (0.5 μg/ml) inadequate to support growth, 7β‐OH cholesterol exerts a synergistic effect on growth. The 7β‐OH cholesterol was incorporated unchanged from the growth medium and could be recovered exclusively in the membrane fraction. The incorporation of the 7β‐OH cholesterol has no effect on the total phospholipid content but the DPG to PG ratio was markedly decreased. Exchange studies with lipid vesicles revealed that whereas most of the cholesterol underwent exchange, only about 20% of the 7β‐OH cholesterol was exchanged.