Serotyping of Bdellovibrios by Agglutination and Indirect Immunofluorescence

Abstract

A comparative serological study was undertaken to clarify the uncertain interrelationships among various bdellovibrios. A total of 17 predacious (hostdependent) strains and 12 nonpredacious strains were serotyped. Strains were grouped into serotypes on the basis of positive agglutination and strongly positive fluorescence cross-reactions. The results of division of the strains into serogroups by these two methods were identical. Bdellovihrio starrii strain A3.12 and Bdellovibrio stolpii strain UKi2 were found to be antigenically distinct from each other and from the group of strains comprising Bdellovihrio hacteriovorus; the latter was found to be an antigenically heterogeneous group consisting of at least nine serogroups. All nonpredacious strains were found to be related antigenically to their obligately predacious counterparts. An antigen(s) common to all of the Bdellovibrio strains examined was exhibited as weakly positive fluorescence. Selected strains of Bdellovihrio were studied by Ouchterlony immunodiffusion, which confirmed the serogrouping results and provided a technically simple method of serotyping. Further immunochemical characterization of the strains of Bdellovihrio in conjunction with increased knowledge of other differences among strains will likely result in the formation of additional species of Bdellovihrio.

Serogrouping of Halophilic Bdellovibrios from Chesapeake Bay and Environs by Immunodiffusion and Immunoelectrophoresis

“…The serologic heterogeneity of the halophilic Bd is manifest by these findings. This is consistent with findings that there may exist several serologic groups of nonhalopililic Bd (4,10) and that one nonhalophilic species alone (B. bacteriovorus) may contain as many as nine distinct serogroups. Of special interest was the finding that all 10 aquarium antigen preparations of Bd cross-reacted with antisera produced against an aquarium isolate.…”

“…Immunological parameters alone, or in combination with other techniques, may be useful tools in the taxonomy of halophilic Bd. Nonhalophilic Bd have been separated into several serologically distinct subgroups which may share a common antigen (2,5,10). Little is known regarding the number of different halophilic subgroups of Bd.…”

“…Biochemical tests are not reliable since it may be difficult to distinguish between reactions caused by contaminating prey metabolic enzymes and reactions of bdellovibrios (Bd). Little is known of the nutritional and metabolic characteristics of the Bd, and these characteristics are not useful taxonomically (10). The result has been little or no progress in defining subgroups of Bd and little upon which to base taxonomic status and appropriate classification.…”

“…define the subgroups of the Bd. Immunological studies involving the terrestrial Bd have resulted in several serologically distinct subgroups which may share a common antigen (2,5,10). Because little is known regarding the number of different halophilic subgroups of Bd, and no immunologic characterization of the halophilic Bd has ever been reported in the literature, a study of the serological relationships among various halophilic strains of Bd was undertaken.…”

A proposal for the reclassification of Bdellovibrio stolpii and Bdellovibrio starrii into a new genus, Bacteriovorax gen. nov. as Bacteriovorax stolpii comb. nov. and Bacteriovorax starrii comb. nov., respectively.

“…High levels of diversity among Bdellovibrio species has also been demonstrated using physiological and cultural characteristics such as fatty acid composition , antibiotic resistance patterns and enzymic activities (H. N. Williams, unpublished data). An analysis of serological properties (Schelling et al, 1977), phage typing and physiological properties of the organisms has revealed that all three recognized species (B. bacteriovorus 100 T , B. stolpii Uki2 T and B. starrii A3.12 T ) form distinct groups (Althauser et al, 1972 ;Hashimoto et al, 1970 ;Varon & Levisohn, 1972).…”