1.Growth of bacteria isolated from the purified tracts of
Aporrectodea caliginosa earthworms (81 strains, 1) and the
soddypodzolic soil (89 strains, 2) on humic acid from brown
coal (HAc) as the single carbon source (0.1 mg/ml). Here and
in Figs. 2 and 3, the mean values of the optical density at
492 nm are given for all the bacteria tested (n = 2).