Revealing azo-dye decolorization of indigenous Aeromonas hydrophila from fountain spring in Northeast Taiwan

This study provides a first attempt to seek for indigenous strains with excellent decolorization capability for dye-laden wastewater treatment from an unpolluted and likely the most biodiverse region (Lanyang Plain) in Northeast Taiwan. For isolation, serial selections were conducted by using of the fungicide nystatin and model diazo-dye C.I. reactive red 141 (RR141). Thirteen bacterial strains (NIU 01–13) with the excellent capability of azo-dye decolorization were predominantly isolated from samples of a fountain spring near Chiao-Hsi in Lanyang Plain. According to profiles of protein expression and PCR-augmented 16S rRNA gene analyses for strain identification, >98% of gene sequences in isolated strains NIU 01 and NIU 12 were similar to Aeromonas hydrophila compared to available gene sequences in the NCBI BLAST gene bank. Phase-curve profiles indicated that azo-dye decolorization was found to be non-growth associated for isolated strains. Color removal efficiency of the culture was ca. 16-fold to that of Pseudomonas luteola, indicating a promising feasibility of isolated cultures to be used for practical treatments. This point apparently suggested that exploring a biodiverse indigenous microbiota with high performance of specific characteristics (e.g., color removal) from a unpolluted region (e.g., Northeast Taiwan) for practical applications should still be possible.