Rhizobium melilotiB323 cells were suspended in deionized water, phosphate buffer pH 6.5 and 5.5 and these buffers supplemented with Ca2+, Mg2+(1 mmol/l) and Fe3+(0.1 mmol/l). Initial cell count was 1.108cells/ml. The viable count of rhizobia suspended in buffer at pH 6.5, with and without salts, remained constant or even increased during storage. Cells suspended in buffer at pH 5.5 with salts, decreased in numbers in the first 5 months, then, until the 10th month, the count remained at 105cells/ml. Rhizobia suspended in buffer at pH 5.5 and deionized water decreased in viability almost to zero by the 10th month. In those suspensions where viability was maintained, the symbiotic infectivity of cells was also maintained as compared with a control performed with fresh cultured rhizobia. In suspensions in deionized water and buffer at pH 5.5 where the viability diminished during the experiment, the rhizobia lost their ability to infect roots immediately after inoculation but maintained their capacity to form late nodules on the hosts.
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