TABLE 2.

Amounts and relative sizes of uronic acid-containing material secreted by Alg⁺ P. aeruginosa FRD1 and its Alg⁻ algKΔ derivative FRD1100

Strain	Relevant genotype	Uronic acid concn (μg/ml) in treated samplesa
		Dialyzed against same vol	Dialysate of same vol	Dialyzed exhaustively
FRD1	algK+	1,800	70	1,800
FRD1100	algKΔ	700	700	0

^aMAP culture supernatants of FRD1 and FRD1100 were dialyzed against an equal volume (7 ml) of Tris-HCl buffer. Uronic acids in the bag and those small enough to diffuse into the dialysate were determined by the carbazole method. Both supernatants contained high concentrations of uronic acids, but only the algKΔ mutant (FRD1100) produced dialyzable uronic acids. The low values obtained with negative control strain FRD1105 were subtracted as background values to produce the values shown. Following extensive dialysis against buffer, all uronic acids produced by FRD1 remained in the sac, but all those produced by FRD1100 had diffused out of the dialysis sac and became undetectable.