Rich growth medium promotes an increased on Mn(II) removal and manganese oxide production by Serratia marcescens strains isolates from wastewater.

Abstract

This study investigated the performance of two different strains of Serratia marcescens on the manganese (II) removal and the effects of the nutrient-rich (NB medium) and nutrient-poor culture (K medium) media on this process. In the NB medium, the pigmented LG1 strain and the non-pigmented CL11 strain exhibited improved growth and higher Mn(II) tolerance (0–2000 mg L−1 ). In addition, improved Mn(II) removal (64.25%) and increased formation of Mn oxides were observed in this medium, especially for the LG1 isolate. EELS analysis revealed Mn inside the cell for LG1 and EDX analysis revealed Mn outside of the cell for CL11, indicating that the two strains remove Mn(II) via distinct mechanisms. The biooxidation of Mn by the CL11 strain may involve indirect mechanisms which alter the pH of the medium, whereas the LG1 strain may use a direct mechanism for the biooxidation mediated by cellular components such as intracellular proteins. These results demonstrate the biotechnological potential of the two strains. In addition, is the first time the high potential of the NB medium for Mn removal is demonstrated. This medium was found to greatly influence the Mn removal and oxide formation, especially in the case of the pigmented LG1 isolate.