School of Resource & Environmental Sciences, Hubei Key Laboratory of Biomass Resource Chemistry and Environmental Biotechnology, Hubei Research Center of Environment Remediation Technology, Wuhan University, Wuhan, 430079, PR China.
National Central City Research Institute, Zhengzhou Normal University, Zhengzhou, 450044, PR China.
Chemosphere. 2021 Jan;263:127952. doi: 10.1016/j.chemosphere.2020.127952. Epub 2020 Aug 13.
Forage grasses have recently received a remarkable amount of attention as promising candidates for decontaminating metal-polluted soils, but this strategy is time-consuming and inefficient. The present study aimed to address the beneficial effects of screened plant growth-promoting rhizobacteria (PGPR) strains Bacillus sp. EhS5 and EhS7 on perennial ryegrass and tall fescue. Single or combined inoculation considerably increased the biomass yield and Cu content of inoculated ryegrass compared with uninoculated plants, thereby enhancing the extraction efficiency at different Cu contamination levels. Bioaugmentation did not show a positive impact on the improvement of fescue's phytoextraction efficiency. Principal component analysis (PCA) and Pearson correlation coefficient results identified root development and photosynthesis as the key variables influencing ryegrass biomass. Antioxidant activities and Cu bioavailability are the key variables influencing Cu accumulation. The inoculated ryegrass showed improved photosynthetic status as the photosystem II system efficiency parameters increased and energy dissipation in the form of heat (DI/RC) decreased with the help of PGPR. The root length, diameter, surface area, and forks of inoculated ryegrass increased remarkably. The levels of scavengers of reactive oxygen species were enhanced in these plants. Moreover, PGPR significantly increased soil Cu bioavailability by secreting siderophores and organic acid and by increasing soil organic carbon content. Dual inoculation showed better results than individual inoculation in improving ryegrass growth and Cu translocation under high Cu contamination level according to PCA. This study systematically explored the effects and mechanisms of the Bacillus-ryegrass combined remediation and provided a novel method for cleaning Cu-contaminated sites.
近年来，饲用牧草作为修复金属污染土壤的有前途的候选者受到了广泛关注，但这种策略既耗时又低效。本研究旨在探讨筛选出的植物促生根际细菌（PGPR）菌株芽孢杆菌 EhS5 和 EhS7 对多年生黑麦草和高羊茅的有益影响。与未接种植物相比，单一或组合接种显著增加了接种黑麦草的生物量产量和铜含量，从而提高了不同铜污染水平下的提取效率。生物强化对提高羊茅草的植物提取效率没有积极影响。主成分分析（PCA）和 Pearson 相关系数结果表明，根发育和光合作用是影响黑麦草生物量的关键变量。抗氧化活性和铜生物利用度是影响铜积累的关键变量。接种黑麦草的光合作用状态得到改善，因为光合作用 II 系统效率参数增加，以热（DI/RC）形式耗散的能量减少，这得益于 PGPR 的帮助。接种黑麦草的根长、直径、表面积和叉子显著增加。这些植物中清除活性氧物质的水平得到了增强。此外，PGPR 通过分泌铁载体和有机酸以及增加土壤有机碳含量，显著提高了土壤铜的生物利用度。根据 PCA，双接种在提高高铜污染水平下黑麦草的生长和铜转运方面的效果优于单接种。本研究系统地探讨了芽孢杆菌-黑麦草联合修复的效果和机制，为修复 Cu 污染场地提供了一种新方法。
