Interaction Mechanisms between 6:2 Fluorotelomer Sulfonic Acid (6:2 FTSA) and Soil-Soybean System: Insight from Biodegradation, Phytotoxicity, and Microbial Shifts

As an important perfluorooctanesulfonate (PFOS) substitute, 6:2 fluorotelomer sulfonic acid (6:2 FTSA) has been widely detected in soil. However, the interaction mechanisms between 6:2 FTSA and the soil-plant system are still unknown. Here, we explored the biodegradation, phytotoxicity, and microbial impact of 6:2 FTSA in a soil-soybean system. The biodegradation of 6:2 FTSA in plants was mediated by both enzymes and coexisting microorganisms. 6:2 FTSA (2.97 nmol/g) inhibited soybean growth and caused oxidative damage, while soybeans enhanced their stress tolerance and metabolism of 6:2 FTSA by modulating genes involved in fatty acid metabolism, hormone signaling, oxidative stress, xenobiotic detoxification, and transmembrane transport. 6:2 FTSA affected rhizospheric and root endophytic microbial communities, with symbiotic fungi being more sensitive to 6:2 FTSA stress than bacteria. Five 6:2 FTSA-degrading rhizospheric and endophytic bacterial strains belonging to genera <i>Acinetobacter</i><i>,</i> <i>Rhodococcus</i>, and <i>Klebsiella</i> were isolated and identified, with the rhizosphere bacteria exhibiting more effective degradation. Our findings reveal the ecological risks and detoxification mechanisms of emerging PFOS alternatives in soil-crop systems.