芽孢杆菌及其胞外多糖对空心菜和茼蒿Cd吸收及土壤团聚体的影响

本研究旨在探究产胞外多糖芽孢杆菌对蔬菜镉(Cd)积累及土壤结构的影响。采用以空心菜和茼蒿为供试材料的盆栽试验,研究了功能菌株Priestia megaterium YG35和Bacillus halodurans G20降低蔬菜吸收Cd的效果和可能作用机制。结果表明,与CK相比,菌株YG35、菌株G20及其胞外多糖处理显著增加空心菜和茼蒿可食用组织干质量(37.8%～115.1%),显著降低可食用组织Cd含量(21.9%～44.2%),并使茼蒿Cd含量(0.057～0.061 mg·kg^-1)达到安全可食用标准,显著降低根际土壤有效态Cd含量(3.7%～11.7%),显著(P<0.05)增加根际土壤多糖含量(35.9%～49.5%)和蔗糖酶活性(15.3%～28.4%),促进根际土壤团聚体向大粒径转化。研究表明,YG35和G20及其胞外多糖能降低蔬菜对Cd的吸收,促进蔬菜生长,改善土壤结构,具有在Cd污染土壤上实现蔬菜安全生产的应用潜力。

Effects of Bacillus and its exopolysaccharide on water spinach and crown daisy Cd uptake and soil aggregates

The study investigated the effect of exopolysaccharide-producing Bacillus strains on reducing Cd accumulation in stem vegetables and soil structure. A pot experiment was used with water spinach and crown daisy as test vegetables to investigate the effects and potential mechanisms of action of the test functional strains Priestia megaterium YG35 and Bacillus halodurans G20 in reducing Cd uptake by vegetables. Compared with the CK, the Priestia megaterium YG35, Bacillus halodurans G20, YG35 EPS, and G20 EPS treatment groups significantly increased the dry weight of edible tissues（37.8%-115.1%）, significantly reduced the Cd content of edible tissues（21.9%- 44.2%）, brought the Cd content of crown daisy（0.057-0.061 mg·kg^-1）to safe edible standards, significantly reduced the available Cd content of vegetable rhizosphere soil（3.7% - 11.7%）, significantly increased the polysaccharide content（35.9% - 49.5%）and sucrase activity（15.3% - 28.4%）of vegetable rhizosphere soil（P<0.05）, and promoted the conversion of soil aggregates to larger grain sizes. Exopolysaccharide-producing bacterial strains YG35 and G20 and their EPS reduce the Cd accumulation of vegetables, promote vegetable growth, improve soil structure, and remediate Cd-contaminated soil for safe vegetable production.