Research Progress in Bioremediation of Heavy-Metal Contaminated Soil

In recent years, the heavy metal pollution of soil is becoming more and more serious, it has been a serious problem to human health and social development. At the same time, the remediation techniques also are developed rapidly, especially the development of bioremediation technologies, providing an efficient, eco-friendly way to solve this problem. This paper provides a brief introduction to the characteristics and present situation of heavy metals contaminated soils in China, and comparisons of the traditional physical and chemical remediation techniques with the bioremediation technologies, features and developments of bioremediation, especially in phytoremediation and micro-remediation were reviewed, in order to give a basis for other studies in this area. Recently, with an overall and systematic view, bioremediation through systematic biology, metagenomics and transgenic techniques were introduced to solve the unsteady problem for bioremediation under different conditions. In terms of phytoremediation, studies were mainly focused on transgenic plants, cell engineering technology to strengthen phytoremediation, develop crop plants for phytoremediation. Micro-remediation was focused on screening new microorganisms and plant-microorganism combined bioremediations. The development of bioremediation faces many problems, first of all, most current studies are still in laboratory and small-scale stages, large-scale studies are rare, although some remediation techniques worked well in the laboratory, when applied to engineering practice, the environment factors becoming complicated and uncontrollable, a series of problems would be happening. Secondly, it is hard to repair severe heavy metal pollution only using bioremediation, as bioremediation is based on the metabolic activity of cells, every creature has a certain range of tolerance to heavy metal, beyond the range, the effect of bioremediation will be greatly reduced; Finally, the instability of bioremediation is also a big problem which limits its large-scale application. the solutions for those problems can be summarized in four aspects: 1) Cultivating and selecting plants that are highly capable of accumulating of pollutants, screening more suitable microbes, as biological materials for bioremediation. 2) Using advanced bio-technologies to modify biomaterials, such as gene transformation, cell fusion, cell hybridization, and biological mutagenesis, etc. 3) Regarding the bioremediation as a system, through the methods of genomics, proteomics, to understand the metabolic pathway and mechanism, using the method of systems biology and bioinformatics, controlling the bioremediation process, improving the stability of bioremediation. 4) Application of the new technologies and new methods. In this field, new technologies and methods were often found; people should combine bioremediation with that, in order to increase the efficiency of restoration. 5) Development of associated remediation. Because every remediation technique has its limitations, in practice, the best way to remediate must be associated with methods. © 2017, Editorial Department of Scientia Silvae Sinicae. All right reserved.