Long-term effect of acetylene on denitrifying N2O production: performance and microbial community

The work utilizes the long-term cultivation with acetylene to obtain highly efficient N2O recovery, relying upon the inhibition of acetylene to N2O reductase. Long-term domestication of acetylene at high concentrations (volume fraction >40 percent) results in the high N2O accumulation of 98.6 percent during the nitrite denitrification process. High throughput 16S rRNA gene analysis showed that Saprospiraceae dominated the microbial community at the end of the cultivation period with the abundance increasing from the initial 3.2 percent to 42.2 percent. Metagenomic analysis revealed that the cultivation under high level acetylene did not lead to the directed screening of microflora lacking nosZ. Instead, nosZ2 harboring bacteria gradually dominated in the bioreactor. Batch experiments in the absence of acetylene demonstrated the N2O reduction capability of the biomass could be restored rapidly upon removal of the acetylene inhibitor. These results indicate acetylene has a transitory impact on the enzyme that is rapidly lost upon removal. This study broadens an high yield methods of N2O production during nitrite denitrification for the energy recovery and improves our understanding of the long-term effect of acetylene on denitrifying community.