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Abstract
Motility of Agrobacterium tumefaciens C58C1 consisted of long straight runs, with relatively few tumbles. Speeds of up to 60 μm s−1 and runs of up to 500 μm were recorded. The propulsive mechanism appeared to resemble that of Rhizobium. Chemotaxis towards carbohydrates resolved four groups of sugars: chemoattractants with peaks at 10−6 m (sucrose, glucose and fructose); 10−5 m (maltose, lactulose and galactose); 10−4 m (raffinose, stachyose and arabinose); and weak or non-attractants (palatinose, lactose, cellobiose and xylose). In descending order, the magnitude of the responses was as follows: sucrose ⪢ maltose > lactulose > glucose > galactose/fructose > stachyose/arabinose/raffinose. The amino acids valine and arginine were good chemoattractants with peaks at 10−3 m, but no significant attraction was observed with alanine, cysteine, methionine or glycine. These results are indicative of a highly sensitive chemotaxis system towards sugars in A. tumefaciens C58C1, and suggest a role for this process in the ecology of the organism.
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