Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040, Pakistan; School of Environmental Sciences, University of Guelph Ridgetown Campus, Ridgetown, N0P 2C0, Canada.
Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040, Pakistan.
J Environ Manage. 2020 Jul 1;265:110522. doi: 10.1016/j.jenvman.2020.110522. Epub 2020 Apr 7.
Cadmium (Cd) is a toxic heavy metal with unknown biological role. Interactive effect of Enterobacter sp. MN17 and biochar was studied on the growth, physiology and antioxidant defense system of Brassica napus under Cd contaminated soil. A multi-metal tolerant endophytic bacterium, Enterobacter sp. MN17, was able to grow in tryptic soy agar (TSA) medium with up to 160, 200, 300, 700, 160 and 400 μg mL of Cd, Cu, Cr, Pb, Ni and Zn, respectively. Paper and pulp waste biochar was prepared at 450 °C and applied to pots (7 kg soil) at a rate of 1% (w/w), while Cd was spiked at 80 mg kg soil. Application of Enterobacter sp. MN17 and biochar, alone or combined, was found effective in the amelioration of Cd stress. Combined application of Enterobacter sp. MN17 and biochar caused the maximum appraisal in shoot and root length (52.5 and 76.5%), fresh and dry weights of shoot (77.1 and 70.7%) and root (81.2 and 57.9%), photosynthetic and transpiration rate (120.2 and 106.6%), stomatal and sub-stomatal conductance (81.3 and 75.5%), chlorophyll content and relative water content (RWC) (78.4 and 102.9%) than control. Their combined use showed a significant decrease in electrolyte leakage (EL), proline, malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), glutathione S transferase (GST) and superoxide dismutase (SOD) by 39.3, 39.4, 39.5, 37.0, 39.0 42.1 and 30.8%, respectively, relative to control. Likewise, the combined application of bacterial strain MN17 and biochar reduced Cd in soil by 45.6%, thereby decreasing its uptake in root and shoot by 40.1 and 38.2%, respectively in Cd contaminated soil. The application of biochar supported the maximum colonization of strain MN17 in the rhizosphere soil, root and shoot tissues. These results reflected that inoculation with Enterobacter sp. MN17 could be an effective approach to accelerate biochar-mediated remediation of Cd contaminated soil for sustainable production of crops.
镉（Cd）是一种具有未知生物作用的有毒重金属。本研究探讨了耐多金属内生菌 Enterobacter sp. MN17 与生物炭在镉污染土壤中对油菜生长、生理和抗氧化防御系统的交互作用。耐多金属内生菌 Enterobacter sp. MN17 能够在含有高达 160、200、300、700、160 和 400μg mL 的 Cd、Cu、Cr、Pb、Ni 和 Zn 的胰蛋白酶大豆琼脂（TSA）培养基中生长。纸浆和造纸废物生物炭在 450°C 下制备，并以 1%（w/w）的比例添加到盆（7kg 土壤）中，同时在土壤中添加 80mg kg 的 Cd。单独或组合使用 Enterobacter sp. MN17 和生物炭都能有效缓解 Cd 胁迫。Enterobacter sp. MN17 和生物炭的联合应用导致地上部和根长（52.5%和 76.5%）、地上部和根鲜重（77.1%和 70.7%）和干重（81.2%和 57.9%）、光合和蒸腾速率（120.2%和 106.6%）、气孔和亚气孔导度（81.3%和 75.5%）、叶绿素含量和相对水含量（RWC）（78.4%和 102.9%）均达到最大评价。与对照相比，其联合使用可使电解质泄漏（EL）、脯氨酸、丙二醛（MDA）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPX）、谷胱甘肽 S 转移酶（GST）和超氧化物歧化酶（SOD）分别显著降低 39.3%、39.4%、39.5%、37.0%、39.0%、42.1%和 30.8%。同样，细菌菌株 MN17 和生物炭的联合应用将土壤中的 Cd 减少了 45.6%，从而使根和地上部对 Cd 的吸收分别减少了 40.1%和 38.2%。生物炭的应用支持了菌株 MN17 在根际土壤、根和茎叶组织中的最大定植。这些结果表明，接种 Enterobacter sp. MN17 可能是一种有效途径，可加速生物炭介导的 Cd 污染土壤修复，实现作物的可持续生产。
