Temperature-induced changes in a microbial community under autotrophic denitrification with sulfide

Abstract 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). NO 3 − and HS − were simultaneously removed at 25–10 °C range. Average HS − -S removal was 98 and 89% at 25 and 10 °C, respectively. While NO 3 − 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. β -Proteobacteria (mainly Thauera sp. and Alicycliphilus sp.) predominated at 25 °C (64%), when the S 0 accumulation was the highest (45%). Decreasing temperature to 10 °C, reduced both the abundance of β -Proteobacteria (2.3 times to 28%) and the accumulation of S 0 (2.5 times to 18%). At 10 °C, chemolithoautotrophic sulfide-oxidizing bacteria belonging to Sulfurimonas sp. and Thiobacillus sp. were present in the biomass (over 34% of all sequences) while S 0 ss and SO 4 2− production increased slightly. These results indicate that temperature-induced changes in the microbial community influenced reactor performance and effluent characteristics, especially S 0 accumulation.