This study investigated temperature-induced changes in a microbial community performing autotrophic denitrification with HS- for S-0 recovery. The study was performed over 120 days in an expanded granular sludge bed (EGSB) reactor at invariable feeding conditions (0.4 kg S/m(3) d loading rate and 0.35 N/S molar ratio). NO3- and HS were simultaneously removed at 25-10 degrees C range. Average HS--S removal was 98 and 89% at 25 and 10 degrees C, respectively. While NO3- was completely removed in studied temperature range. High-throughput sequencing indicated that the transition from methanogenic conditions (inoculum sludge) to the imposed experimental conditions led to development of a Proteobacteria dominated phylum. beta-Proteobacteria (mainly Thauera sp. and Alicyckliphilus sp.) predominated at 25 degrees C (64%), when the S-0 accumulation was the highest (45%). Decreasing temperature to 10 degrees C, reduced both the abundance of beta-Proteobacteria (2.3 times to 28%) and the accumulation of S-0 (2.5 times to 18%). At 10 degrees C, chemolithoautotrophic sulfide-oxidizing bacteria belonging to Sulfurimonas sp. and Thiobacillus sp. were present in the biomass (over 34% of all sequences) while S-ss(0) and SO42- production increased slightly. These results indicate that temperature-induced changes in the microbial community influenced reactor performance and effluent characteristics, especially S-0 accumulation.