OUTER-MEMBRANE PROTEIN HETEROGENEITY WITHIN PSEUDOMONAS-FLUORESCENS AND P-PUTIDA AND USE OF AN OPRF ANTIBODY AS A PROBE FOR RIBOSOMAL-RNA HOMOLOGY GROUP-I PSEUDOMONADS

The electrophoretic patterns of outer membrane proteins of strains rep resenting the biovars of Pseudomonas fluorescens and Pseudomonas putid a were analyzed by gel electrophoresis, The outer membrane protein pro files were variable, and they were not useful for assigning strains to a specific biovar, However, three or four predominant outer membrane proteins migrating at 42 to 46 kDa, 33 to 38 kDa, and 20 to 22 kDa wer e conserved among the strains, They could be tentatively identified as OprE (44 kDa), OprF (38 kDa), OprH (21 kDa), and OprL (20.5 kDa), whi ch are known proteins from Pseudomonas aeruginosa. A 37-kDa OprF-like protein was purified from P. fluorescens DF57 and used to raise a poly clonal antibody, In Western blot (immunoblot) analysis, this antibody reacted with OprF proteins from members of Pseudomonas rRNA homology g roup I but not with proteins from nonpseudomonads. The heterogeneity i n M(r) of OprF was greater among P. fluorescens strains than among P. putida strains, Immunofluorescence microscopy of intact cells demonstr ated that the antibody recognized epitopes that were accessible only a fter unmasking by EDTA treatment, The antibody was used in a colony bl otting assay to determine the percentage of rRNA homology group I pseu domonads among bacteria from the rhizosphere of barley. The bacteria w ere isolated on 10% tryptic soy agar, King's B agar, and the pseudomon ad-specific medium Gould S1 agar, The estimate of OprF-containing CFU in rhizosphere soil obtained by colony blotting on 10% tryptic soy aga r was about 2 and 14 times higher than the values obtained from King's agar and could S1 agar, respectively, indicating that not all fluores cent pseudomonads are scored on more specific media, The colonies reac ting with the OprF antibody were verified as being rRNA homology group I pseudomonads by using the API 20NE system.