A Comparison of the Survival of Intraperiplasmic and Attack Phase Bdellovibrios with Reduced Oxygen

The ability of intraperiplasmic and attack phase bdellovibrios to survive and/or grow under anoxic and microaerobic conditions was examined. Both halotolerant and nonhalotolerant bdellovibrio strains were examined. In all instances, the bdellovibrio strains were unable to grow under anoxic conditions, but were able to survive for periods of time in both the extracellular and intraperiplasmic forms. However, the intraperiplasmic organisms were observed to survive longer. Increased temperature hastened the loss of viability of both forms of the predatory bacteria in oxic and anoxic environments. Under microaerobic conditions, halotolerant bdellovibrios were observed to grow, although at a slightly reduced rate than in atmospheric oxygen, while two nonhalotolerant isolates survived but did not grow. The ability of attack phase bdellovibrios to survive in an anoxic environment for up to nine days and their growth or survival under microaerobic conditions greatly expands the possible ecological niches in which the predators may be active members of the microbial community.