Attachment of Alcaligenes to rice roots

The processes of attachment to rice roots of the associative diazotroph Alcaligenes faecalis were examined. Three modes of attachment of A. faecalis were distinguished: adsorption, anchoring and colonization, proposed as a result of using an 15N-labelling technique and Tn5-induced mutants. Che− mutants affected adsorption, but not anchoring. Exo−Che− mutant was defective in both adsorption and anchoring. Exo− or Exo++ mutants were only defective in anchoring. Effective colonization was necessary for establishment of the associative system. Pectinase and exopolysaccharide (EPS) played important roles in the association between the host plant and bacteria.