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Liquid Nitrogen Storage of Phytopathogenic Bacteria. L. W. Moore, Assistant Professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; René V. Carlson, Former Laboratory Assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331, Present address: 4086 W. 13th Ave., Vancouver, B.C., Canada. Phytopathology 65:246-250. Accepted for publication 20 September 1974. DOI: 10.1094/Phyto-65-246.

A simple, uniform method of culture storage in liquid nitrogen was developed to preserve selected species of Agrobacterium, Corynebacterium, Erwinia, Pseudomonas, and Xanthomonas. Survival of cells was generally enhanced by suspending them in 10% skim milk before freezing and storage. However, the most convenient procedure was to freeze and store all species except the "soft-rotting" types in the culture medium in which they were grown. Regardless of the nature of the suspending fluid, the viability of rapidly-frozen cells usually declined immediately after freezing, but remained stable thereafter through 12 and 30 months of storage at –172 to –196 C. By contrast, viability dropped rapidly over a 6-month period for several species stored at –20 C, but survival was enhanced in 10% skim milk. Pathogenicity was unaffected by storage under liquid nitrogen.