Fig. 4.

Purification of growth-promoting compounds from yeast extract.

(A) Yeast extract powder was sequentially extracted with ethyl acetate, acetone and methanol. The methanol extract was separated by reverse-phase (RP) column chromatography using an ODS column as described in Materials and Methods. (B) Growth assays were performed in the basal medium supplemented with reverse-phase column chromatography fractions (panel A). The turbidity was measured using a 96-well plate reader at 490 nm. YE, yeast extract.