FIG 2.

Germination and outgrowth of B. subtilis 2-, 47-, and 98-day spores in rich or minimal medium. Spores harvested from sporulation plates after 2, 47, or 98 days were purified as described in Materials and Methods. Spores were then incubated at 37°C in either L broth plus l-valine (A) or Spizizen’s minimal medium plus l-alanine (B) as described in Materials and Methods, and spore germination, outgrowth, and vegetative growth were followed by measuring the OD₆₀₀ of the cultures. The symbols used are as follows: ○, 2-day spores; ●, 47-day spores; and ▵, 98-day spores. This experiment was carried out twice, with essentially identical results.