Modern genetics and genomics research increasingly depends on large collections of recombinant microorganisms such as the bacterium Escherichia coli, transformed with plasmids or other type of molecular clones.  The collections can number in the thousands to hundreds of thousands, and are typically stored in 96- or 384-well plates.  For example, a complete collection of full length human cDNAs (~20,000 clones of human full length messenger RNAs) occupies about 250 96-well plates.  These are stored frozen at -80˚C and thawed before sampling. A typical requirement is to isolate a subset of 10, 100 or 1000 such clones for further studies, and this is done sterilely using a small pipette toothpick or other sterile instrument to transfer small numbers of cells into fresh growth medium, where the cells are expanded and the DNA is prepared for further studies.

We have designed built and tested a prototype device that fully automates the strain retrieval process under conditions that only transiently thaw the sample of interest rather than the entire multiwell plate.  Hundreds of strains can be picked per hour with full hands off automation.  The core of the system is a commercial robotic freezer that stress over 900 multiwell plates.  Condensation is minimized by the maintenance of a dry nitrogen environment in the freezer and throughout the picking system.  A heated pin thaws the well of interest transiently and moves the picked sample to a destination well containing growth medium.  The sample well quickly refreezes due its proximity to adjacent frozen wells. The now contaminated pin is sterilized by an ethanol heat treatment and returned to a carousel system. As the plate remains outside the freezer for only one to a few minutes, the remaining wells do not thaw.  Other applications of and enhancements to the system will be discussed.

See-J-Boeke’s-Presentation-Automated-Retrieval-of-Viable-Microorganism-Samples