While all strains, with the exception of E4(1), possessed a constitutive tellurite reductase, its location was unknown. Therefore, strains were fractionated and each fraction monitored for reduction. No reductase activity was observed in the periplasm of any strain (Figure 3D), however, E1, E5, KR99, RB3, and RB 16-17 all possessed activity in the spheroplast and spheroplast lysate (Figure 3E,F). In the case of E4(1), no activity was observed in any fraction with or without prior exposure to TeO32− (Figure 3G,H), strictly confirming a possibility of reduction in intact cells only. Upon separation of the membranes from the cytoplasmic contents, activity was detected for E1, E5, KR99, RB3, and RB 16-17. The rate of reduction was calculated for each fraction (Figure 4). Strain KR99 possessed the highest rate of 0.284 units in the membranes. The strain with the second highest rate was E5 (0.159 units in the membranes), followed by E1 (0.056 units in the membranes), RB3 (0.038 units in spheroplast), and RB 16-17 (0.024 units in spheroplast).