Comparative assessment upon dye removal capability of indigenous bacterial strains from Lanyang Plain in northeast Taiwan

This study provides a first attempt from a geological and ecological perspective to look forward isolations of indigenous strains with the decolorization capability from the most biodiverse region in Taiwan for dye-laden wastewater treatment. Serial selections were conducted by a specific use of the fungicide nystatin and model azo dye C.I. reactive red 141 (RR141) during isolation. Several bacterial strains with the excellent capability of azo dye decolorization were predominantly isolated from river water and mud samples of Lanyang River Basin. Phase-curve profiles indicated that azo dye decolorization was found to be non-growth associated for both mixed cultures and isolated pure strains. The color removal efficiency of the mixed culture was nearly 10-fold to that of Pseudomonas luteola at ca. 600 mg L−1 RR141, indicating a promising feasibility of isolated cultures to be applicable for practical treatments. The decolorization performance of unacclimated and acclimated pure cultures was at most 20% and 70-80% to that of the mixed cultures, respectively. It might suggest that combined interactions among decolorizers were crucial for the optimal color removal. According to the results of physiological and 16S rRNA gene sequence examinations, the isolated strains should belong to Aeromonas species (very likely A. hydrophila).