On the other hand, the potential toxicities of the samples collected at the end of the anaerobic (WWanaer) and aerobic (WWfinal)reaction phases of a typical GSBR1 cycle (day 25 in Fig. 2) were, ingeneral, similar to those observed for the two FSBR1 cycles (Figs.7 and 6, respectively). However, the treatment cycles of GSBR1towards the end of the reported experimental period (day 71) led,comparatively, to a remarkable decrease in toxicity with respect to effects in either yeast growth (Fig. 7A) or modification in the expression of the three toxicity-indicator genes (Fig. 7B). Indeed,the respective values at the end of the aerobic reaction phase(WWfinal) were close to those measured in the feed solution without dye (WWcontrol, Fig. 7). These results suggest that the AGS system allowed the establishment of a more diverse microbial population in the SBR with the ability to aerobically convert the aromatic amines formed during anaerobic azo dye reduction. Overall, there sults are thus consistent with an almost complete abatement of the potential cytotoxicity and genotoxicity, toward the yeast, of the textile wastewater after anaerobic treatment, possibly due to the biodegradation of potentially toxic azo dye byproducts, in parallel with high decolorization and COD removal levels in the AGS SBR system. However, it should be noted that the yeast-based assays provide a fast preliminary toxicity screening and for a full toxicity evaluation of wastewater treatment efficacy more complex and ecologically relevant toxicity tests are needed [16].