AGGLUTINATION OF PSEUDOMONAD CELLS BY PLANT-PRODUCTS

Cells of plant pathogenic and saprophytic species of pseudomonads were differentially agglutinated by preparations from Dark Red kidney bean leaves. Water homogenates of bean leaves caused agglutination of the saprophytic pseudomonads Pseudomonas fluorescens and P. putida but no agglutination of the plant pathogens P. phaseolicola or P. syringae. Agglutination with P. tabaci was variable. The agglutinin was detected in both pellet and supernatant after centrifugation of the water homogenate at 6000 g for 10 min. This agglutinin was protease and trypsin stable, was insensitive to salt except above 0·15 M and required a divalent metal ion for activity. An agglutinin with apparently different properties was released by 0·3 m NaCl treatment of a crude preparation. of isolated bean leaf cell walls. This wall-released agglutinin caused a more variable agglutination of both saprophytic and pathogenic pseudomonads. The wall agglutinin was protease and trypsin labile and was inhibited by salt or metal ions above 0·02 m. Agglutination of pseudomonad cells by characterized plant components was also demonstrated. Pectin and galacturonic acid but not other plant cell wall polysaccharides produced agglutination. The plant lectins concanavalin A, wheat germ agglutinin and phytohemagglutinin but not ricin caused agglutination of the bacterial cells. © 1979.