Abstract
The effects of bdellovibrio infection on host permeability and respiration were investigated by measuring respiration rates and the rate of o-nitrophenyl-beta-d-galactopyranoside hydrolysis during the course of single infection cycles of Bdellovibrio bacteriovorus strain 109 growing on Escherichia coli ML 35 (lac i(-)z(+)y(-)). The data show that among the very early consequences of parasite attack on the host are an increase in permeability and a general disruption of respiratory activity of the host, and it is suggested that both phenomena stem from early damage to host membrane. The rapid onset of damage after inception of the cycle and the failure of streptomycin to prevent the damage indicate that complete penetration of the parasite into the host is not a requirement for the observed effects. The data also show that bdellovibrio does not use host energy-generating mechanisms for its growth and suggest that the parasites may have a search mechanism that permits them, to some degree, to distinguish between infected and uninfected hosts.