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Aims <p>Pioneer plants can reorganize soil bacterial communities across contaminated habitats, yet how they shape microbial assembly and co-occurrence under long-term Sb and associated metal(loid) contamination remains unclear. This study examined plant- and soil-associated patterns of microbial community assembly across the Xikuangshan (XKS) mining area.</p> Methods <p>Rhizosphere, bulk, and unvegetated contaminated control soils were collected from ten sites across XKS, and soil physicochemical properties and total and DTPA-extractable metal(loid) fractions were measured. Bacterial communities were profiled by 16S rRNA gene sequencing (Illumina MiSeq). Diversity analyses, multivariate regression trees (MRT), aggregated boosted trees (ABT), LEfSe, and co-occurrence network analysis were used to assess community differences, identify key environmental drivers, and characterize statistical bacterial associations.</p> Results <p>Rhizosphere soils showed higher α-diversity and a distinct community composition relative to bulk and unvegetated contaminated control soils. Community variation was primarily associated with soil pH, organic matter, and DTPA-extractable Sb and As, with pH and bioavailable Sb accounting for most between-group dissimilarity; MRT models explained 52.3–72.0% of variation, and the co-occurrence network comprised 58 nodes and 107 statistically supported edges. <i>Pedomicrobium</i> and <i>Kaistobacter</i> were enriched in rhizosphere soils, whereas <i>Solibacter</i> and <i>Conexibacter</i> characterized bulk/control soils. Co-occurrence networks in the rhizosphere were more cohesive and highly connected, while non-rhizosphere networks were looser and weaklier connected; several genera (e.g., <i>Sulfobacillus</i> and <i>Acidocella</i>) were negatively correlated with plant bioconcentration factors (BCFs).</p> Conclusions <p>Pioneer vegetation was associated with higher rhizosphere bacterial diversity relative to bulk and unvegetated contaminated soils, reflected by denser bacterial co-occurrence under polymetallic stress. Soil pH and bioavailable Sb emerged as important constraints associated with compartment-specific community organization. Together, these patterns point to a compartment-specific bacterial response pattern that requires future functional validation.</p>

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Plant- and soil-associated bacterial assembly and co-occurrence networks in long-term Sb-contaminated soils of the Xikuangshan mining area

  • 期刊论文

  • 发表日期：

    2026年7月24日

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  • Guangyuan Tu,
  • Wanqin Huang,
  • Yong Wang,
  • Qi Liao,
  • Mengying Si,
  • Weichun Yang,
  • Qingzhu Li,
  • Zhihui Yang

摘要

Aims

Pioneer plants can reorganize soil bacterial communities across contaminated habitats, yet how they shape microbial assembly and co-occurrence under long-term Sb and associated metal(loid) contamination remains unclear. This study examined plant- and soil-associated patterns of microbial community assembly across the Xikuangshan (XKS) mining area.

Methods

Rhizosphere, bulk, and unvegetated contaminated control soils were collected from ten sites across XKS, and soil physicochemical properties and total and DTPA-extractable metal(loid) fractions were measured. Bacterial communities were profiled by 16S rRNA gene sequencing (Illumina MiSeq). Diversity analyses, multivariate regression trees (MRT), aggregated boosted trees (ABT), LEfSe, and co-occurrence network analysis were used to assess community differences, identify key environmental drivers, and characterize statistical bacterial associations.

Results

Rhizosphere soils showed higher α-diversity and a distinct community composition relative to bulk and unvegetated contaminated control soils. Community variation was primarily associated with soil pH, organic matter, and DTPA-extractable Sb and As, with pH and bioavailable Sb accounting for most between-group dissimilarity; MRT models explained 52.3–72.0% of variation, and the co-occurrence network comprised 58 nodes and 107 statistically supported edges. Pedomicrobium and Kaistobacter were enriched in rhizosphere soils, whereas Solibacter and Conexibacter characterized bulk/control soils. Co-occurrence networks in the rhizosphere were more cohesive and highly connected, while non-rhizosphere networks were looser and weaklier connected; several genera (e.g., Sulfobacillus and Acidocella) were negatively correlated with plant bioconcentration factors (BCFs).

Conclusions

Pioneer vegetation was associated with higher rhizosphere bacterial diversity relative to bulk and unvegetated contaminated soils, reflected by denser bacterial co-occurrence under polymetallic stress. Soil pH and bioavailable Sb emerged as important constraints associated with compartment-specific community organization. Together, these patterns point to a compartment-specific bacterial response pattern that requires future functional validation.