Abstract: A system for the preparation of biological agents can include a vessel in which the biological agents are fermented and in which the fermentation is monitored by a probe detection means. Probe support means are fastened to the wall of the vessel to support the probe detection means with its operative end within the vessel and to provide access from outside the vessel to the output of the probe detection means. The probe support means has a seal-engaging surface at its forwardmost end within the tank. A seal is seated on the probe detection means forwardly of probe support means, and a seal compression member is fastened to the probe support means to compress the seal between the seal-engaging surface of the probe support means, the seal compression means, and the outer surface of the probe detection means to limit the collection of fermentation material to the exposed outer surfaces of the system and permit cleansing and sterilization of the system.