Unlocking metabolic suppression in Acinetobacter baumannii with synergistic N-P-surfactant to enable petroleum...

Addressing the urgent need for remediation of petroleum-contaminated saline-alkaline soils, this study developed a synergistic system (NTQ) integrating the chemical surfactant Tween 80, ammonium nitrogen, phosphorus, and exogenous Acinetobacter baumannii. The NTQ treatment achieved highly efficient petroleum hydrocarbon degradation of 61.2 % within 40 days, significantly outperforming individual remediation strategies and other combined approaches. Mechanistic analysis revealed that microbial metabolism in saline-alkaline soil was severely constrained by (p)ppGpp‑mediated inhibition of nitrogen assimilation. In the NTQ system, phosphorus alleviated microbial metabolic inhibition by modulating the spoT/ppx-gppA pathway to reduce (p)ppGpp levels, while ammonium nitrogen directly mitigated nitrogen starvation. This dual action induced a metabolic reprogramming and reshaped the microbial community into a synergistic, function-complementing consortium. This consortium was structured around the dominant indigenous genus Alcanivorax (29.9 %), collaborating with salt-tolerant degraders (Pseudomonas, Marinobacter, Halomonas) and effectively integrating with the exogenous A. baumannii. Concurrently, key functional genes involved in terminal alkane oxidation (e.g., alkB, fadE, aceE) and aerobic aromatic degradation (e.g., benB-xylY, pcaL) were significantly enriched. Concomitant with efficient petroleum removal, a marked increase in soil sucrase and dehydrogenase activities was observed. This study establishes a novel bioremediation paradigm centered on relieving (p)ppGpp-mediated metabolic suppression for efficient petroleum cleanup in saline-alkaline ecosystems.