Rizvi Asfa, Ahmed Bilal, Zaidi Almas, Khan Mohd Saghir
Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University Aligarh 202002 Uttar Pradesh India
RSC Adv. 2019 Feb 19;9(11):6125-6142. doi: 10.1039/c9ra00333a. eCollection 2019 Feb 18.
Heavy metals are toxic environmental contaminants, which severely affect microbial composition and functions and, concurrently, crop production. Due to these issues, the present study focussed on the selection of metal tolerant microbes endowed with metal detoxification abilities and their role in the management and remediation of metal contaminated soils. The metal tolerant bacterium BM2, identified as by 16SrRNA gene sequencing, survived well under metal pressure and tolerated 1600 and 2000 μg mL of Ni and Pb, respectively. The inhibitory impact of metals on wheat increased consistently with a progressive increase in metal concentration. Deposition of Ni and Pb within root and leaf and oxidative stress were validated by SEM, EDX and CLSM. The overall growth parameters of wheat grown under metal stress were improved following BM2 colonization. As an example, with 195 mg Pb kg enhanced the length and dry biomass of shoots by 14% and 23%, respectively, over the control. Also, strain BM2 improved the grain yield significantly by 49% at 870 mg Ni kg and by 50% at 585 mg Pb kg compared to uninoculated plants. Moreover, BM2 relieved the metal stress on wheat and caused a significant drop in proline and malondialdehyde content and the activities of antioxidant enzymes, like catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) This study, therefore, provided solutions to the metal toxicity problems faced by winter wheat and clearly suggests that the metal detoxification potential of BM2 could be greatly useful in the management of metal polluted soils.
重金属是有毒的环境污染物，严重影响微生物组成和功能，同时也影响作物产量。鉴于这些问题，本研究聚焦于筛选具有金属解毒能力的耐金属微生物及其在金属污染土壤治理和修复中的作用。通过16SrRNA基因测序鉴定的耐金属细菌BM2，在金属压力下存活良好，分别耐受1600和2000μg/mL的镍和铅。金属对小麦的抑制作用随着金属浓度的逐渐增加而持续增强。通过扫描电子显微镜（SEM）、能量散射X射线光谱仪（EDX）和共聚焦激光扫描显微镜（CLSM）验证了镍和铅在根和叶中的沉积以及氧化应激。在BM2定殖后，金属胁迫下生长的小麦的整体生长参数得到改善。例如，在195mg/kg铅处理下，与对照相比，地上部长度和干生物量分别提高了14%和23%。此外，与未接种的植株相比，在870mg/kg镍和585mg/kg铅处理下，菌株BM2显著提高了小麦籽粒产量，分别提高了49%和50%。此外，BM2缓解了小麦的金属胁迫，导致脯氨酸和丙二醛含量以及过氧化氢酶（CAT）、超氧化物歧化酶（SOD）和谷胱甘肽还原酶（GR）等抗氧化酶的活性显著下降。因此，本研究为冬小麦面临的金属毒性问题提供了解决方案，并明确表明BM2的金属解毒潜力在金属污染土壤治理中可能非常有用。
