Fig. 1. Growth of L. casei in the presence of NaHSeO₃. Growth of L. casei in (a, b) MRS or (c, d) MRS supplemented with NaHSeO₃. Red color of NaHSeO₃-supplied culture compared to standard culture indicates the presence of red elemental selenium. Optical microscopy images (magnification 100×) of bacteria grown in (b) MRS or (d) MRS supplemented with NaHSeO₃ indicate the presence of intracellular sphere-shaped conglomerates only in NaHSeO₃-supplied culture. (e) CFUs in L. casei cultures grown in MRS (LC) or MRS supplemented with NaHSeO₃ (LCSe). Both cultures were grown for 19 h with an inoculum of 10⁷ CFUs per ml. CFUs were determined by agar plate counting and three plates per sample were examined. Results presented are representative of three independent experiments. Asterisk indicates a statistically significant difference (Student's t-test, p ≤ 0.001).