Mn(II) Oxidation by Batch Cultures of Pseudomonas putida Strain EC112

Manganese(II) oxidation by a new bacterium isolate, Pseudomonas putida strain EC112, was studied in batch reactors over a range of Mn(II) concentrations (1-26mg/L) in a chemically defined liquid medium (at pH 6.5 and 30 degrees C). Bacterial Mn(II) oxidation initiated after the exponential growth phase and carbon source consumption. The best fit kinetic oxidation parameters of half-saturation coefficient Ks=1.086 +/- 0.029mg/L and maximum specific substrate utilization rate constant k=0.180 +/- 0.003mg Mn(II)/(mgdrycellmassh) were obtained using Monod-type kinetics and fitted with the Levenberg-Marquardt nonlinear least-squared algorithm. Additional experiments assessed the potential of Mn(II) oxidation by strain EC112 in the presence of the oxidation products of humic acid (HA) and manganese dioxide (MnO2). Results show enhanced biological Mn oxidation and growth. This suggests MnO2 oxidizes biologically refractory organic matter to substrates that support microorganism growth.