Decolorization of Textile Wastewater by a Mixed Culture of Enterococcus faecalis and Bacillus subtilis

摘要

Textile wastewater is the second largest source of river water pollution in the world. Therefore, it is necessary to develop more efficient microbial decolorization processes for sustainable water management. Recently, the number of reports of dye-decolorizing bacteria has increased. Several studies reported that bacterial consortia decolorized dyes more efficiently than single strains; however, the mechanism underlying this phenomenon is unknown. We investigated this phenomenon by comparing decolorization activity of a mixed culture with that of single strain cultures under various growth conditions and cell densities. We used two newly isolated strains of bacteria: Enterococcus faecalis strain T6-al having dye decolorization azoreductase activity, and Bacillus subtilis strain S4-ga that did not have dye decolorizing activity. The mixed culture of the T6-al and S4-ga strains decolorized dyes at higher efficiencies and at faster rates than that by single strain cultures. The S4-ga strain lowered the ORP (redox potential) of the mixed culture when mixed with the T6-al strain. Thus, we found that the S4-ga strain influenced the decolorizing activity of the T6-al strain.