Characterization of germination and activation of Bdellovibrio bdellocysts.

A simple method of assaying germination of bdellocysts in liquid medium has been devised. Bdellocysts can be induced to germinate by any of eight L-amino acids or the monovalent cations K+ and NH4+. L-Glutamine was the best individual inducer of germination, although the resulting rate of germination was much slower than in a complex medium. The use of a defined germination medium containing L-glutamine, KCl, and NH4Cl produced a faster rate of germination than did complex media. Bdellocysts germinated most rapidly at pH 8.0 and at 35 degrees C and required aerobic conditions. Respiration of bdellocysts began to increase at 3 min after the addition of germinants. Germination was inhibited by respiratory-chain inhibitors and by inhibitors of macromolecular synthesis. When bdellocysts were heat shocked at sublethal temperatures for short periods, there was no effect on the rate of germination in the defined germination medium or in the complex medium. However, heat-shocked bdellocysts germinated at a much faster rate in the presence of single inducers of germination when compared to nonshocked bdellocytes.