Metagenomics and metatranscriptomics uncover the microbial association with high S0 production in a denitrifying desulfurization granular sludge reactor

Denitrification desulfurization process is a promising technology for elementary sulfur (S0) production from sulfide contained wastewater. However, the microbial community associated with high S0 production is not still well studied. This study establishes an efficient denitrification S0 production bioreactor based on inoculating the anaerobic granular sludge. In the optional S/N molar ratio of 7:2, 80 % of the influent sulfide was transferred to be high quality element sulfur with the purity of 92.5%. Meanwhile the total inorganic nitrogen removed efficiency keep stable at ~80%. Reads-based metatranscriptomic analysis found that the abundance of the expressed gene encoding sulfide-quinone reductase (sqr) was 10-folder than that of the gene encoding flavocytochrome c sulfide dehydrogenase subunit B (fccB). Moreover, the expression level of sqr was also significantly higher than Dsr gene encoding for dissimilatory sulfate reductase, the common key S0 oxidation enzyme. Metagenomic binning analysis confirm that sulfur-oxidizing bacteria (SOB) utilizing sulfide-quinone reductase (sqr) was highly to be the functional bacteria responding for the high S0 production in the reactor. Meanwhile, an unexpected enrich in methanogens and the high expression activity of the stickland bacteria were indicated the cooperative relationship of the acetoclastic methanogens and SOB. Findings from this research provides an alternative biotechnology for sulfide contained wastewater treatment and sheds light on the microbial interaction associated with high S0 production.