The development and application of automated gridding for efficient screening of yeast and bacterial ordered libraries

An automated gridding procedure for the inoculation of yeast and bacterial clones in high-density arrays has been developed. A 96-pin inoculating tool compatible with the standard microtiter plate format and an eight-position tablet have been designed to fit the Biomek 1000 programmable robotic workstation (Beckman Instruments). The system is used to inoculate six copies of 80 x 120-mm filters representing a total of ~20,000 individual clones in approximately 3 h. High-density arrays of yeast artificial chromosome (YAC) and cosmid clones have been used for rapid large-scale hybridization screens of ordered libraries. In addition, an improved PCR library screening strategy has been developed using strips cut from the high-density arrays to prepare row and column DNA pools for PCR analysis. This strategy eliminates the final hybridization step and allows identification of a single clone by PCR in 2 days. The development of automated gridding technology will have a significant impact on the establishment of fully versatile screening of ordered library resources for genomic studies.