Co-Metabolic Mechanism Analysis of Sulfidogenesis and Acidogenesis for Mariculture Solid Waste Treatment: Key Functional Microorganisms and Enzymes

Sulfidogenesis is a non-negligible process during theacidogenicfermentation of mariculture solid waste (MSW), and its interactionswith acidogenesis are still unclear. To fill this gap, this studyexplored the co-metabolism mechanisms of acidogenesis and sulfidogenesisduring the acidogenic fermentation of MSW with thermal (TH) pretreatment,alkaline fermentation (AF), and their combination (TH-AF) pretreatment.The interactions of sulfidogenesis and acidogenesis were altered bythe changes in substrate availability and fermentation environmentunder the intervention of TH and AF pretreatments. Both acidogenesisand sulfidogenesis were boosted with TH pretreatment by supplyingadequate substrates, and their competition for substrates was alleviated.Moreover, sulfidogenesis was constrained by 87.3% with TH-AF pretreatment,which reduced volatile fatty acid (VFA) consumption by sulfate reductionbacteria (SRB) and further enhanced the VFA accumulation. Notably,acidogenesis could be promoted by sulfidogenesis due to the enhancementof MSW hydrolysis and enrichment of acidogenic bacteria (Prolixibacter, Ruminococcus, etc.). Different pretreatments couldredirect the metabolic pathways by changing the types of key functionalmicroorganisms and enzymes in MSW anaerobic fermentation. Overall,this study provides useful information for developing an efficientand sustainable treatment of MSW. Sulfidogenesisstrengthened acidogenesis by enhancing thehydrolysis of mariculture solid waste and enriching acidogenic bacteria.