Department of Environmental Sciences, Fatima Jinnah Women University, Rawalpindi, Pakistan.
Department of Biotechnology, Fatima Jinnah Women University, Rawalpindi, Pakistan.
PLoS One. 2022 Nov 10;17(11):e0277101. doi: 10.1371/journal.pone.0277101. eCollection 2022.
Phytoremediation assisted with plant growth promoting bacteria (PGPB) is a green technology to remediate metal contaminated soils. Plants usually produce secondary metabolites to tolerate metal toxicity. Present study was designed to explore the phytoremediation potential of Vigna radiata var. NM-II in the presence of metal resistant PGPB and comparison of metabolites produced under heavy metal stresses (Pb, Ni, Cr). Three PGPB selected for present study include Bacillus pumilus MB246, Serratia nematodiphila MB307 and Delftia Lacustris MB322. Pot experiments were conducted with inoculated V. radiata NM-II seeds grown in soil artificially contaminated with lead (Pb), Nickle (Ni) and chromium (Cr) at a concentration of 300, 200 and 100 mg/kg respectively. After harvesting various growth parameters were studied (root length, shoot length, fresh weight and dry weight). Bacterial colonization on root surfaces of harvested plants was observed through Scanning electron microscopy (SEM) and Elemental composition was recorded through Energy dispersive X-ray spectroscopy (EDX) attached with SEM. Metabolic response of harvested plants was studied through Gas chromatography Mass spectrophotometry (GC-MS) analysis. Metal accumulation in roots, shoots and soil was analysed by acid digestion method from which Bioaccumulation factor (BF) and Translocation factor (TF) of metal from soil to plant was calculated. Results revealed stimulatory effect of PGPB on growth and phytoextraction ability of V. radiata. Soil metal removal efficiency was in the order Pb>Ni>Cr, whereas metal distribution in each part of plant was root>stem>leaf. The BF and TF values suggested V. radiata as Pb and Ni excluder while moderate accumulator for Cr. Elemental analysis through Energy Dispersive X- ray spectroscopy (EDX) found potassium (K+)and calcium (Ca+)as highly abundant nutrients with least accumulation of sulphur (S). Metabolites study through GC-MS revealed variety of compounds (carbohydrates, amino acids, fatty acids, steroids etc) detected differentially under each metal treatment and their concentration was influenced by different bacterial inoculations. Overall 9-Octadecenamide was found as commonly present lipid compound in most of the treatments which is required for detoxification in plants. The study concluded beneficial role of PGPB for successful phytoremediation of heavy metals and differential response of metabolites towards each metal stress that is related to metal tolerance ability of V. radiata.
利用植物促生菌（PGPB）辅助的植物修复是一种修复重金属污染土壤的绿色技术。植物通常会产生次生代谢物来耐受金属毒性。本研究旨在探索在金属抗性 PGPB 存在的情况下，豇豆 NM-II 的植物修复潜力，并比较在重金属胁迫（Pb、Ni、Cr）下产生的代谢物。本研究选择了三种 PGPB，包括解淀粉芽孢杆菌 MB246、粘质沙雷氏菌 MB307 和德氏乳杆菌 MB322。在接种了 V. radiata NM-II 种子的盆栽实验中，土壤中人工添加了浓度分别为 300、200 和 100mg/kg 的铅（Pb）、镍（Ni）和铬（Cr）。收获后，研究了各种生长参数（根长、茎长、鲜重和干重）。通过扫描电子显微镜（SEM）观察了收获植物根表面的细菌定殖情况，并通过与 SEM 相连的能量色散 X 射线能谱（EDX）记录了元素组成。通过气相色谱质谱联用仪（GC-MS）分析研究了收获植物的代谢反应。通过酸消解法分析了根系、茎部和土壤中的金属积累情况，由此计算了金属从土壤到植物的生物积累因子（BF）和迁移因子（TF）。结果表明，PGPB 对豇豆的生长和植物提取能力有刺激作用。土壤金属去除效率的顺序为 Pb>Ni>Cr，而植物各部分的金属分布为根>茎>叶。BF 和 TF 值表明豇豆是 Pb 和 Ni 的排除者，而对 Cr 则是中度积累者。通过能量色散 X 射线能谱（EDX）分析发现，钾（K+）和钙（Ca+）是含量丰富的营养物质，而硫（S）的积累最少。通过 GC-MS 研究发现，在每种金属处理下，都检测到了不同的化合物（碳水化合物、氨基酸、脂肪酸、类固醇等），其浓度受不同细菌接种的影响。总的来说，发现 9-十八烯酰胺是大多数处理中常见的脂质化合物，这是植物解毒所必需的。该研究得出结论，PGPB 对重金属的成功植物修复具有有益作用，而代谢物对每种金属胁迫的不同反应与豇豆的金属耐受能力有关。
