Fig. 2.

Heme detection in fecal samples. Feces of germ-free and conventional mice, and of newborn and adult humans were tested for their capacity to stimulate B. thetaiotaomicron growth in the gel setup. Feces samples resuspended to 100 mg/ml in 0.9 % NaCl were heated to 90 °C for 10 min; 50 μl (5 mg feces) was deposited in each well. Heme (310 ng) was used as control. The deposited samples are as indicated above each well. a. The gel contains Bt in M17-glu 0.2 %. b. The gel is as in "A", to which we added heme (2.5 μM) to mask the effect of heme supplied by samples. Note that baseline growth of Bt is stimulated by heme throughout the gel (region of the gel indicated at right by the green bracket). The same samples as in "A" were loaded. The gel shown was prepared without sugar to lower bubble formation due to CO₂ production; however, comparable results are obtained in the presence of 0.2 % to 0.5 % glucose. The gels shown are representative of at least 20 germfree and 10 conventional mouse feces, and 5 meconiums and 3 human adult feces samples tested in this way