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Continuous discharge of wastewater, emissions, and solid wastes from steelworks poses environmental risks to ecosystems. However, the role of keystone taxa in maintaining multifunctional stability during environmental disturbances remains poorly understood. To address this, we investigated the community diversity, assembly mechanisms, and soil multifunctionality of soils collected from within the steelworks (I), within 2.5 km radius from the steelworks (E), and from an undisturbed area (CK) in Jiangsu Province, China, via 16 S rRNA sequencing. Significant differences were found in the Chao1 and the richness indexes of the total taxa (p < 0.05), while the diversity of keystone taxa was not significant at each site (p > 0.05). The deterministic processes for total taxa were 42.9%, 61.9% and 47.7% in CK, E, and I, respectively. Steelworks stress increased the deterministicity of keystone taxa from 52.3% in CK to 61.9% in E and I soils. The average multifunctionality indices were 0.518, 0.506 and 0.513 for CK, E and I, respectively. Although the soil multifunctionality was positive correlated with α diversity of both the total and keystone taxa, the average degree of keystone taxa in functional network increased significantly (79.96 and 65.58, respectively), while the average degree of total taxa decreased (44.59 and 51.25, respectively) in the E and I. This suggests keystone taxa contribute to promoting the stability of ecosystems. With increasing disturbance, keystone taxa shift their function from basic metabolism (ribosome biogenesis) to detoxification (xenobiotics biodegradation, metabolism, and benzoate degradation). Here we show that keystone taxa are the most important factor in maintaining stable microbial communities and functions, providing new insights for mitigating pollution stress and soil health protection. [Display omitted] • Disturbance of steelworks reduces soil multifunctionality • Both total and keystone taxa diversity contribute to soil multifunctionality • Assembly processes of keystone taxa support high ecological stability • Keystone taxa rely on various metabolic pathways to maintain multifunctionality [ABSTRACT FROM AUTHOR]

Earthworms are important in soil bioremediation because of their capability of pollutant degradation. However, the trade-off between pollutant dissemination and degradation arising from earthworm activities remains unclear, as well as the potential biodegradation mechanism. Herein, an earthworm avoidance experiment was established to investigate Metaphire guillelmi –mediated tetracycline (TC) diffusion and degradation. The results showed that above 1600 mg kg−1 TC pollution in soil induced avoidance behaviour of earthworms (p < 0.05), below which the random worm behaviour accelerated TC diffusion by 8.2% at most (p < 0.05), resulting in elevated levels of antibiotic-resistant bacteria and genes in the soil. Nevertheless, earthworms enhanced TC degradation regardless of whether their avoidance behaviour occurred (14.6–25.8%, p < 0.05). Compared with in soil, metabolic pathways affiliated with xenobiotic degradation and metabolism in the intestines were enriched (LDA >3). Given the abundant glutathione S-transferases in the intestines and their close relationship with Δ degradation , they may play a key role in intestinal TC biodegradation. In general, earthworms had good tolerance to soil TC contamination and their impact on promoting TC degradation outweighed that accelerating TC diffusion. This work provides a comprehensive view of earthworms as a potential remediation method for TC-contaminated soil. • Earthworms accelerated tetracycline (TC) diffusion in soil. • TC diffusion increased antibiotic resistance bacteria/gene abundance in adjacent soil. • Earthworm presence enhanced TC degradation regardless of behaviour. • Glutathione S-transferases played a key role in intestinal TC degradation. • The stimulating effect of earthworms on TC degradation overweighed diffusion. [ABSTRACT FROM AUTHOR]