S6: Cultivation in various types of microtiter plates, and the quantification of cell mass using flatbed scanning and image analysis software

Since bioassays and other analytical methods require less and less sample material, ever smaller microbial culture volumes suffice for microbial screenings and optimization studies for fermentative and biotransformation processes. The challenge of the last decade has been to miniaturize cultivation systems, while maintaining the quality of growth and axenicity as traditionally achieved in shake flasks and stirred bioreactors. The use of standard microtiter plates for this purpose is particularly attractive because of the availability of compatible robots, readers, and other equipment.

The presentation will focus on state-of-the-art methods for turning the individual wells from microtiter plates into high-quality "mini-bioreactors". Topics include the hydrodynamics, degree of turbulence, and oxygen transfer rates (OTRs) that can be achieved in 24, and 96 well microtiter plates with either square deepwells or round wells, in combination with well-closure systems that are necessary to maintain axenicity, prevent cross-contamination, limit the evaporation rate, and to limit the headspace refreshment rates during vigorous orbital shaking.

Other topics are methods for synchronization of cultures growing in different wells of one MTP, and the use of flatbed- scanning technology in combination with image analysis software to follow the growth in multiple MTPs in time.