Growth of Bacillus subtilis and Spore Germination in Soil Observed by a Fluorescent-antibody Technique

Vegetative bacteria of Bacillus subtilis placed in contact with an acid forest soil initially declined in number but grew after the development of fungal hyphae. Growth did not occur in sterile soil, nor in alkaline forest soil unless fungal growth was stimulated. Spores of B. subtilis would not germinate in the same acid forest soil unless fungal growth took place, and hardly germinated at all in the alkaline soil. Roots of seedlings of Pinus sylvestris inhibited both vegetative growth and spore germination. These results are consistent with the observed distribution of vegetative bacteria and spores of B. subtilis in forest soils.