TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred System: The reaction vessel is a cylindrical cylinder resting on a flat base and in its upper and lower parts with two tubes for connecting to the effluent and supply pipes. The internal structure comprises a circular arrangement of guide rods on a central tube, for receiving the cylindrical tubes containing the support units, a central tube not attached to the reaction vessel, an oxygenation system and a thermostat system. The support units are inside tubes of mesh material and provide independent sections to avoid the units becoming compressed. The tubes are introduced into the reactor via guide rods joined to a round profile structure that allows the tubes to be manipulated independently, so that the colonization step can be accelerated and the support units can be removed, without having to empty the reactors or stop the reactor for more periods longer than 2 hours. The round profile structure is a concentric arrangement, to reduce the total volume of the internal structure of the reactor. The guide rods and round structure are joined to a central tube that allows the internal structure of the reactor to be lifted up and removed for maintenance work. The oxygenation and thermostat systems are connected to the central tube, and the air and water pipes for these systems are inside this tube. The oxygenation system comprises a supply of air to the central tube and diffusers in the base of the internal structure, to provide an adequate aeration and agitation of the fermentation medium. The air guide and diffuser structure has a serpentine, spiral arrangement that allows the optimum temperature for microorganism growth to be maintained. The cover allows liquid and gas to be removed from the reactor and it is secured to the reaction vessel by a quick-action lock without screws. The cover comprises an assembly of plates which rotate in parallel at an angle to the ground. Instruments are provided, e.g. for controlling temperature, controlling the level of medium inside the reactor and measuring pH.