FIG. 1.

NO₃⁻ reduction by S. putrefaciens in the presence of 50 mmol liter⁻¹ hematite (▪) and without hematite (□) and NO₂⁻ production/reduction in the presence of 50 mmol liter⁻¹ hematite (•) and without hematite (○). Error bars indicate the standard deviations of the means (n = 3).