“…A spiral [2] was attached from bottom to top on the inside wall of the medium sterilizing unit vessel. Inoculation was aided by the action of external electric rotary vibrator (MVSI 3, 300 W, Italvibras) [3], which together with the spiral structure caused the culture medium to move upwards in the vessel. At the end of the spiral there was a big outlet which led to the vertical downcomer tube [4].…”