Arsenic (As), distributed widely in the natural environment, is a toxic substance which can severely impair the normal functions in living cells. Research on the genetic determinants conferring functions in arsenic resistance and metabolism is of great importance for remediating arsenic-contaminated environments. Many organisms, including bacteria, have developed various strategies to tolerate arsenic, by either detoxifying this harmful element or utilizing it for energy generation. More and more new arsenic resistance (ars) determinants have been identified to be conferring resistance to diverse arsenic compounds and encoded in ars operons. There is a hazard in mobilizing arsenic during gold-mining activities due to gold- and arsenic-bearing minerals coexisting. In this study, we isolated 8 gold enrichment strains from the Zijin gold and copper mine (Longyan, Fujian Province, China) wastewater treatment site soil, at an altitude of 192 m. We identified two Brevundimonas nasdae strains, Au-Bre29 and Au-Bre30, among these eight strains, having a high minimum inhibitory concentration (MIC) for As(III). These two strains contained the same ars operons but displayed differences regarding secretion of extra-polymeric substances (EPS) upon arsenite (As(III)) stress. B. nasdae Au-Bre29 contained one extra plasmid but without harboring any additional ars genes compared to B. nasdae Au-Bre30. We optimized the growth conditions for strains Au-Bre29 and Au-Bre30. Au-Bre30 was able to tolerate both a lower pH and slightly higher concentrations of NaCl. We also identified folE, a folate synthesis gene, in the ars operon of these two strains. In most organisms, folate synthesis begins with a FolE (GTP-Cyclohydrolase I)-type enzyme, and the corresponding gene is typically designated folE (in bacteria) or gch1 (in mammals). Heterologous expression of folE, cloned from B. nasdae Au-Bre30, in the arsenic-hypersensitive strain Escherichia coli AW3110, conferred resistance to As(III), arsenate (As(V)), trivalent roxarsone (Rox(III)), pentavalent roxarsone (Rox(V)), trivalent antimonite (Sb(III)), and pentavalent antimonate (Sb(V)), indicating that folate biosynthesis is a target of arsenite toxicity and increased production of folate confers increased resistance to oxyanions. Genes encoding Acr3 and ArsH were shown to confer resistance to As(III), Rox(III), Sb(III), and Sb(V), and ArsH also conferred resistance to As(V). Acr3 did not confer resistance to As(V) and Rox(V), while ArsH did not confer resistance to Rox(V).

Arsenic pollution is a global environmental challenge, necessitating efficient and sustainable remediation technologies. This study investigates the synergistic effect of the arsenic-resistant bacterium Burkholderia contaminans ZCC (ZCC) and corn stalk biochar (BC) on arsenic-contaminated soil, with Pteris vittata as the remediation plant. Through pot experiments, we evaluated the effects of various BC addition rates (0%, 1%, 5%) and ZCC inoculation on soil pH, plant growth, physiological responses, and arsenic accumulation. Biochar alone significantly increased soil pH (reaching 7.56 in the 5% BC treatment), while B. contaminans ZCC alone had a weaker effect. In combined treatments, pH changes were primarily driven by biochar. The combination of B. contaminans ZCC and BC enhanced P. vittata growth, with the 5% BC + ZCC treatment showing the greatest increase in total plant biomass (2.56 times that of the control) and total chlorophyll content (43.32% higher). This treatment also activated antioxidant systems (increased SOD, POD, and CAT activities), reduced oxidative damage (lower MDA content), and improved osmotic regulation (higher proline content). Notably, B. contaminans ZCC and BC synergistically enhanced arsenic accumulation in the P. vittata plant, with the arsenic content under the 5% BC + ZCC treatment being 2.81 times that of the control. This study demonstrates that the combination of B. contaminans ZCC and BC enhances arsenic remediation through soil improvement and plant growth promotion.

Microbial inoculants can support sustainable crop production, but mixtures may show non-additive interactions, making formulation compatibility important to evaluate in tea. We tested three inoculant factors in a balanced 2 × 2 × 2 root-drench experiment with Shuixian tea seedlings: laboratory-cultured Burkholderia contaminans ZCC (Z), a Bacillus subtilis-based commercial formulation (B), and a Trichoderma harzianum-based commercial formulation (H). Plant physiology, rhizosphere soil properties, and bacterial 16S rRNA gene and fungal ITS1 communities were assessed across eight treatments. Plant responses were composition dependent: B and HB increased root activity by 68.2% and 60.8%, whereas ZHB reduced it by 56.8%. Soil responses were narrower; ZH and HB increased cellulase, Z increased total N, and ZB decreased total N. All seven factorial terms were significant in the eight-trait plant PERMANOVA, with Z × B explaining the most variation (R² = 0.315), whereas only Z × B was significant for the 11-variable soil matrix (R² = 0.101). For bacterial community structure, Z × B was the only factorial term consistently retained by the high-permutation Aitchison analysis and complementary robustness checks, and ANCOM-BC2 identified 23 robust genus–factorial-term associations. Fungal communities showed broad whole-community restructuring, but no named genus passed the FDR- and sensitivity-based differential-abundance criteria. Apparent plant–microbiome concordance under unrestricted permutations disappeared when permutations were restricted within treatments, indicating shared treatment structure rather than additional within-treatment coupling. Overall, formulation composition and interactions, rather than inoculant number alone, governed the observed responses, supporting factorial compatibility screening before field validation in tea.