菌根真菌对土壤中有机污染物的修复研究

菌根真菌是真菌与植物之间特殊的联合共生体，利用菌根真菌修复土壤，尤其是修复有机污染物污染的土壤，正成为一个崭新的研究方向。菌根真菌是土壤真菌的一种，但与土壤中放线菌和细菌等微生物相比，其对土壤中有机污染物具有更大的忍耐能力，并且能利用土壤中大多数持久性有机污染物作为碳源来获取能量。综述了近20年菌根真菌对土壤有机污染物降解研究，讨论了菌根真菌降解土壤有机污染物的可能机制，并探讨了从引入固氮菌、外源细菌两个方面对菌根调控以提高修复效果的可能性，为进一步研究菌根真菌生物降解土壤中持久性有机污染物、利用菌根植物修复有机污染土壤提供信息。

BIOREMEDIATION RESEARCH OF ORGANIC POLLUTANTS IN SOIL BY MYCORRHIZAL FUNGI

Due to the persistency of soil organic pollutants and their potential risk to the eco environment and human health, there is an increasing urge to remediate organics polluted soils. Biodegradation of soil organic pollutants by rhizosphere microorganisms has been a research focus. Arbuscular mycorrhizal fungi are ubiquitous symbiotic microbes associated with plants. Compared with bacteria and actinomycete,mycorrhizal fungi are more tolerant to organic pollutants in soil. For instance, some of them can use most persistent organic pollutants (POPs) as exclusive carbon source for obtaining energy. This paper reviewed the research into the relationships among mycorrhizal fungi, plant and organic pollutants during last two decades. The mechanisms of biodegradation of soil POPs by mycorrhizal fungi fall into three categories:(1) Direct degradation: mycorrhizal fungi can excrete enzymes to decompose organic pollutants to low molecular organic matter, carbohydrate, water and other non toxic matter to obtain energy; (2) Co-metabolism: mycorrhizal fungi use readily available or low molecular organics as primary carbon and energy source, and use high molecular organic pollutants as the second substrate; (3) Degradation in the mycor-rhizosphere: the quantities of microorganisms in mycor-rhizosphere soil are up to 1000 times more than those in the bulk soils. Degradation of organic pollutants will be enhanced as a result of joint contribution from microbes living in the mycor-rhizosphere. The inoculation of extraneous microbes such as nitrogen-fixing bacteria and genetically engineered bacteria can be used as a means of mycor rhizosphere control to improve bioremediation efficiency. For instance, the introduction of nitrogen fixing bacteria will change the proposition of the bacteria in mycor rhizosphere soil and reduce C/N to improve the activities of soil microbes. Gene engineering can also be used to modify indigenous bacteria so that they could not only adapt to the local soil conditions easily, but also enhance capability to degrade organic pollutants in soils.