Purification of Halobacteriovorax from plaques and the influence
of Vibrio minicells. Since filtration was unsuccessful, attempts
were made to collect pure Halobacteriovorax by picking
agar from the center of large (5-mm-diameter), clear plaques,
where it was assumed that host cells would have succumbed from
predation. Our results indicate that this was not the case. Some
persistence of host cells remained within the plaques and led to the
outgrowth of vibrios in enrichments of the picked materials. We
hypothesize that V. parahaemolyticus persists within clear plaques
as minicells and that Vibrio minicells are resistant to predation by
Halobacteriovorax. Clearly, minicells are smaller than Halobacteriovorax;
thus, there is no mechanism for Halobacteriovorax to
enter into minicells to replicate. This suggests that minicells may
protect Vibrio populations in the environment from total collapse
as a survival mechanism during periods when Halobacteriovorax
levels are high, thus preserving individual Vibrio species.