Abstract
The microbioassay (MB) method was applied to the detection of galactose in paper chromatography. Mutabile-type variant (M) of Salmonella typhimurium or Escherichia coli, the growth of which is specifically inhibited in the presences of galactose, was used as the test organism. The paper disc was prepared from the sport of galactose on filter paper and placed on agar plate containing M (disc method) ; or the paper disc was cut into pieces and added into cup on the agar plate (cup method) . After overnight incubation at 37°C, the resulting inhibition zone around the disc or cup was measured.
From the experimental results, the cup method appeared to be somewhat more sensitive than the disc method. Galactose could be detected only from the position of Rf =0.2 after the ascending chromatography using the solvent composed of n-butanol, acetic acid and water (4: 1: 5) . The end point of the positive inhibition zone in MB method was 1.2 r. On the other hand, that of the detectable spot by the color reaction (aniline phthalate) was 0.9 r. When galactose solution was mixed with glucose having near Rf value, the size of inhibition zone was almost unchanged, the position of galactose on the filter paper being able to be differentiated from that of glucose by the combination of MB method and color reaction
The MB method proved also to be applicable to the thin layer chromatography of galactose.
