FIG. 1.

Culture conditions affecting capsule production in rare, encapsulated B. cereus strains. Microscopic images captured (at ×100) of B. cereus 03BB87 following incubation (a) at 30°C in HI plus horse serum plus sodium bicarbonate, (b) at 30°C in HI broth, and (c) at 30°C on SBA in 5% CO₂. These images represent the degree of capsule formation observed with India ink staining of cells, noted in Table 1 as +, −, and V, respectively. Each represents three independent experiments, where each of the three test strains and two control strains was cultured under the various growth conditions.