Automated production of high density cosmid and YAC colony filters using a robotic workstation

We report here on a system for automated preparation of high-density colony filters of arrayed libraries using the high density replicating system (HDR) for the Beckman Biomek 1000 robotic workstation. This system, consisting of a 96-pin tool, a sterilization station and controlling software, transfers samples from microplates onto target membranes in arrays up to 36 times the density of a 96-well microplate. The transfer operation can be completely automated with the addition of the Biomek Side Loader System, which consists of a robotic arm capable of transferring plates and filters between the Biomek working tablet and a storage area. Using the complete system, we are able to plate 32 replica filters (8 x 12 cm), each containing the clones from 16 different microplates (i.e., 1536 clones per filter), in a 16-h overnight run without any operator intervention. We describe conditions used for transfer of bacterial yeast colonies and fixation of DNA to the membranes, and we illustrate hybridization results obtained with cosmid and YAC filters.