EDX analysis of electron dense particles formed by cultures of C. testosteroni S44 amended with 1.0 mM sodium selenite. (A) Extracellular particles pointed out by arrows. The emission lines for selenium are shown at 1.37 keV (peak SeLα), 11.22 keV (peak SeKα) and 12.49 keV (peak SeKβ). (B) Intracellular particles pointed out by arrows. No emission peaks of Se.