Refinement of Lyophilization Methodology for Storage of Large Numbers of Bacterial Strains. R. D. Gitaitis, Associate Professor, Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793. Plant Dis. 71:615-616. Accepted for publication 2 February 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0615.

A method was developed for the lyophilization of large numbers of bacterial strains. A heavy loopful of bacteria picked from a 48- to 72-hr culture on an agar medium was mixed with 0.2 ml of sterile evaporated milk in a well of a 96-well plastic microwell tissue culture plate. Bacterial suspensions were frozen for 1 hr at –73 C, then placed in a lyophilizer chamber. Samples were lyophilized for either 5 or 24 hr. After removal from the lyophilizer chamber, the microwell plates were placed under vacuum and heat-sealed in polyethylene bags. Samples were stored at room temperature or at –73 C. Viability of bacteria was checked periodically. A lyophilized pellet was mixed with 0.2 ml of sterile distilled water, and the suspension was streaked on a suitable agar medium. The bacteria have remained viable for at least 1 yr.

Keyword(s): freeze-dry, Clavibacter michiganense subsp. michiganense, Xanthomonas campestris pv. vesicatoria.