Virulence, Serological, and Other Physiological Studies of Bacterium flaccumfaciens, Bact. phaseoli, and Bact. phaseoli sojense

Abstract

Morphological studies resulted in the isolation of a "smooth" and a "rough" strain of Bact. phaseoli sojense and of 2 strains also differing in colony characteristics from pure cultures of the other 2 organisms under discussion. Physiological reactions were recorded on starch agar, gelatin, in various sugar broths, and litmus milk. In the serological studies both the agglutinin and the precipitin tests were used. The 2 strains of Bad. fiaccumfaciens differed morphologically and in the degree of pathogenicity but were identical physiologically, serologically and in the acid agglutination test. The Bact. phaseoli strains differed slightly in their morphological and cultural characteristics and in virulence, but were indistinguishable serologically and by the acid agglutination test. The "smooth" (S) and "rough" (R) strains of Bact. phaseoli sojense differed morphologically, in virulence, and in range of acid agglutination but were indistinguishable in their physiological and serological reactions. "The greater virulence of the S strain seems to be correlated with motility and lesser agglutinability and the lesser virulence of the R strain with low motility or non-motility and with greater agglutinability. In the acid zone there also appears to be a correlation between low P.D. and high agglutination and between high P.D. and low agglutination, but not in the alkaline." The S strain agglutinated only between p H 1.2 and 4.0, while the range of acid agglutination for R extended from p H 2.0 to 9.4 with the exception of p H 5.5 to 5.8. The attempt to differentiate the S and R strains by the precipitin test, using filtrates of broth cultures, failed. The S strain remained constant throughout the investigation but the R strain, though remaining unchanged in culture media, yielded both S and R colonies when passed through soybean plants. " Bact. flaccumfaciens, Bact. phaseoli, and Bact. phaseoli sojense all differ serologically and can be differentiated by the use of the agglutination test. Bact. flaccumfaciens serologically stands apart from Bact. phaseoli and Bact. phaseoli sojense which are quite closely related. This is in harmony with the cultural findings." The isoelectric point for all 3 organisms is between pH 1.2 and 3.0.