Developments in Microbial Communities and Interaction Networks in Sludge Treatment Ecosystems During the Transition from Anaerobic to Aerobic Conditions

The transition between anaerobic and aerobic conditions represents a fundamental ecological process occurring ubiquitously in both natural ecosystems and engineered wastewater treatment systems. This study investigated the microbial community succession and co-occurrence network dynamics during the transition from anaerobic sludge to aerobic cultivation. High-throughput 16S and 18S rDNA sequencing revealed two distinct succession phases: an initial "aerobic adaptation period" (Day 1) and a subsequent "aerobic stable period" (Day 15). Eukaryotic communities shifted from Cryptomycota to the unassigned eukaryotes dominance, while prokaryotic communities maintained Firmicutes and Proteobacteria as core phyla, with persistent low-abundance archaea indicating functional adaptation. Network analysis highlighted predominant co-occurrence patterns between eukaryotic and prokaryotic communities, suggesting synergistic interactions. These findings provide insights into microbial ecological dynamics during anaerobic-to-aerobic transitions, offering potential applications for optimizing wastewater treatment processes.