Introduction to advantages and problems of shaken cultures

Shaking bioreactors are the most frequently used reaction vessels in biotec hnology and have been so for many decades. In spite of their large practica l importance, very little is known about the characteristic properties of s haken cultures from an engineering point of view. The few publications avai lable contain to some extent contradicting statements and conflicting advic e concerning the correct operating conditions of shaking bioreactors. Depen ding on the investigated microbial system, the engineering parameters may m ore or less significantly influence the experimental results in a quantitat ive as well as in a qualitative manner. Unfortunately, these kind of intera ctions are often overlooked or ignored by scientists. Precise knowledge abo ut the controlling hydrodynamic phenomena in shaking bioreactors and quanti tative information about the physical parameters influencing the cultures a re needed to assure reproducible and meaningful operating conditions. In th is introduction, the state of the art of culturing microorganisms in shakin g bioreactors is reviewed and some issues of their practical application in screening and process development projects are addressed. (C) 2001 Elsevie r Science B.V. All rights reserved.