FIG. 3.

Mean bacterial proportions in all samples over the experimental period for pHs 6.8, 7.5, and 8.5, as determined by fluorescence in situ hybridization. Population proportions are expressed as percentages of total bacteria. The inocula were human feces (1% [wt/vol]), and the incubations were carried out in batch cultures for 48 h with phosphatidylcholine as the main substrate at a concentration of 0.5% (wt/vol). Control fermentors did not contain phosphatidylcholine. a, significantly different from the initial sample (P < 0.05); b, significantly different from the initial sample (P < 0.01); c, significantly different from the T48 control (P < 0.05); d, significantly different from the T48 control (P < 0.01); e, significantly different from the T48 sample at pH 7.5 (P < 0.05); f, significantly different from the T48 sample at pH 8.5 (P < 0.05).