Functional activators-facilitated FeS transformation enhances petroleum hydrocarbon degradation by promoting functional microbial proliferation.

Bioremediation of total petroleum hydrocarbon (TPH)-contaminated sites often faces a major challenge in sulfur-rich environments, where ferrous sulfide (FeS) immobilizes pollutants and sharply reduces their bioavailability, thereby stalling remediation. This study demonstrates that the bottleneck can be overcome by applying a composite functional activator to induce a targeted shift of the site microenvironment. The activator first selectively suppresses competing iron- and sulfur-reducing bacteria, reducing their relative abundance by 92%, thereby shifting the microbial community structure. Concurrently, a controlled decrease in local pH converts FeS from a pollutant sink into an active catalyst. The transformed FeS then activates molecular oxygen (O2) to generate reactive oxygen species (•OH and SO4•-), which chemically mobilize and pre-oxidize TPH, producing a "priming effect". This priming effect subsequently restructures the indigenous microbial community. Consequently, under optimized niche conditions and increased nutrient availability, TPH-degrading Bacillus populations expand significantly in the remediation environment: their relative abundance increases by 57%, and their niche breadth widens by 34%. Metagenomic analysis confirms upregulation of genes related to pollutant degradation, substance transport, and energy metabolism, strengthening the metabolic network. Ultimately, the integrated chemical-biological process achieves 90% TPH degradation. This study realizes the functional shift of FeS from remediation barrier to degradation booster, offering an innovative chemo-biological synergistic strategy and engineering paradigm for long-term stable remediation of TPH-contaminated sites.