@article{smith_wollum_1993, title={PHYSICOCHEMICAL AND D-GALACTOSE-MEDIATED INTERACTIONS IN THE ATTACHMENT OF BRADYRHIZOBIUM-JAPONICUM TO ROOTS OF GLYCINE-MAX}, volume={39}, ISSN={["1480-3275"]}, DOI={10.1139/m93-034}, abstractNote={ The roles of electrostatic, hydrophobic, and lectin-mediated interactions in the attachment of Bradyrhizobium japonicum to soybean (Glycine max [L.] Merr.) seedling roots were examined. Cell suspensions (104 cfu/mL) of B. japonicum strain USDA 110 were exposed to excised root segments during 2-h adhesion assays. The presence of the specific hapten for the soybean seed lectin, the sugar N-acetyl-D-galactosamine (GalNac), did not inhibit attachment, but D-galactose did (29% of untreated control). Some D-galactose inhibition (69% of control) was observed when the bacteria were preincubated in the presence of the sugar before the attachment assay but not when the roots were preincubated. Attachment was pH dependent, reaching maximum values between pH 6.0 and 6.5. The polycations DEAE-dextran and poly-L-lysine stimulated adhesion 12- and 5-fold to excised root segments, respectively; DEAE-dextran caused a 7-fold attachment stimulation to intact seedling roots. Segregation of bacterial cells into hydrophobic and nonhydrophobic fractions by preexposure to polystyrene did not affect attachment to roots, nor did the presence of two detergents, sodium dodecyl sulfate and Tween 80. These results indicate that hydrophobic interactions are not involved in the attachment, but anionic repulsion may limit attachment between B. japonicum cells and G. max roots (both surfaces are negatively charged at the assay medium pH of 6.3). The attachment is not via the GalNac-specific soybean lectin but apparently is mediated by a D-galactose-binding moiety located on the bacterial cell surface.Key words: bradyrhizobia, attachment, bacterial lectins, polycations }, number={2}, journal={CANADIAN JOURNAL OF MICROBIOLOGY}, author={SMITH, GB and WOLLUM, AG}, year={1993}, month={Feb}, pages={245–251} }