Response of Neisseria gonorrhoeae to Bdellovibrio species.

Bdellovibrio species are small, highly motile bacteria that are predators upon other bacteria in nature. Bdellovibrios attach to, penetrate, replicate within, and destroy prey that share the general characteristic of gram negativity. The lipopolysaccharide moiety of the cell membrane of target microorganisms appears to contain the principal receptor site for bdellovibrio attachment. Since gonococci also contain lipopolysaccharide that is similar in many respects to that contained within gram-negative rods, studies were conducted to determine the extent of gonococcal interaction with a variety of bdellovibrio species. Despite transient attachment, penetration of gonococci by bdellovibrios never occurred. Failure of bdellovibrio parasitization was unrelated to gonococcal species, colony type, piliation, penicillin susceptibility, or virulence as influenced by passage in embryonated eggs. In experiments involving mixtures of gonococci and more typical gram-negative bacillary prey, the latter were always attacked by bdellovibrios, whereas the former were ignored. Despite evidence for similarities between gonococcal and gram-negative bacillary lipopolysaccharides, resemblances do not extend to the point where gonococci are susceptible to bdellovibrio parasitization.