A study on phosphate uptake by Acinetobacter sp. in presence of arsenate under aerobic condition

Phosphate is the main hindrance for the removal of arsenic from the arsenic contaminated waste water. Therefore, phosphate removal from contaminated water has become imperative for the successful removal of arsenic. In the present study, an attempt was made to remove phosphate from the waste water by Acinetobacter sp. in the presence and absence of arsenate. When phosphate (25 ppm) containing synthetic solution was treated with Acinetobacter sp. at pН 6 at ambient temperature under aerobic condition, the bacterium was able to remove 71.88% (17.97 ppm) phosphate. However, in the presence of arsenate (5 ppm), only 54.24% (13.56 ppm) phosphate uptake was observed from the waste water by Acinetobacter sp. Thus the presence of arsenate (5 ppm) inhibited phosphate uptake by 17.64%. The phosphate uptake by Acinetobacter sp. follows the Michalis-Menten kinetics. In the presence and absence of arsenate, the maximum velocity (Vmax) of phosphate uptake was 1.07 and 1.03 μM mg−1 h−1; while the kinetic constant (Km) was 1.13 and 0.37 mM, respectively. Consequently, arsenate was observed as competitive inhibitor for the phosphate uptake. The data thus underlines the significance of Acinetobacter sp. for the removal of phosphate along with arsenate.