FIG. 2.

Effects of fractionated serum components on NE-induced stimulation of bacterial growth. (a) Viable counts of E. coli strain E2348/69 after 18 h of incubation from an inoculum of 10² CFU/ml in (i) SAPI minimal salts medium, (ii) SAPI medium supplemented with 50 μM NE, (iii) SAPI medium supplemented with 30% bovine serum, and (iv) SAPI medium supplemented with 30% bovine serum and 50 μM NE. (b) Superdex 75 elution profile of 1 ml of bovine serum. (c) viable counts of strain E2348/69 after 18 h of incubation from an inoculum of 10² CFU/ml in SAPI minimal medium supplemented (10%, vol/vol) with filter-sterilized fractions from the column shown in panel b. Assays were performed in the absence (○) or presence (●) of 50 μM NE. (d) SDS-PAGE of proteins in 5-μl aliquots of fractions 6 to 18 of the column shown in panel b; the position of Tf is indicated. Lane M contains marker proteins. Sizes are shown in kilodaltons. Lane S contains 0.5 μl of unfractionated bovine serum, and lane T contains 2 μg of purified human Tf.