土壤生物修复与秸秆快速降解耦合过程的作用机制研究

Facing the severe challenges in the field of soil pollution control and efficient utilization of straw，the fermentation performance and genetic stability of recombinant Trichoderma reesei transformants constructed in our previous research work will be further studied in this project, and the growth kinetics,substrate degradation kinetics and producing enzyme (laccase, cellulase, xylanase) kinetics in solid-state fermentation process by recombinant Trichoderma reesei on straw substrate will also be deep into research. By constructing a new type of straw rapid degradation agent using the recombinant Trichoderma reesei as main role, the straw degradation process with producing high activity laccase is coupled with the bioremediation process of organic pollutants in soil. On the basis of further research on the synergy mechanism of the above coupling process, laccase and lignin degradation intermediates produced in the straw degradation process will be used to build a cheap and safe catalytic system of Laccase / natural mediator in order to avoid the use of expensive laccase preparation and the artificial synthesis mediator which may cause environment pollution problem. The degradation kinetics of typical soil organic pollutants by the laccase/nature mediator catalytic system and the degradation experiment in situ of compound organic pollutants in soil will be further studied. This project aims to explore an economical, environmentally friendly, efficient new way for further enhancing the technology of straw utilization, increasing soil fertility, accelerating the degradation of soil organic pollutants such as pesticides and polycyclic aromatic hydrocarbons, improving the ecological environment, and promoting sustainable development of agricultural production.

针对土壤污染以及秸秆利用方面所面临的严峻挑战，本项目拟对已构建的重组里氏木霉转化子的发酵性能、遗传稳定性及其在秸秆原料上的生长动力学、底物降解动力学和产酶（漆酶、纤维素酶、木聚糖酶等）动力学进行深入研究。以重组里氏木霉为核心构建新型高效秸秆降解剂，将秸秆快速降解并产生高活力漆酶的过程与土壤有机污染物的降解修复过程相耦联，深入研究上述耦联过程的协同作用机制，利用秸秆降解过程产生的漆酶及木质素分解中间产物，构建廉价、安全的漆酶/天然介体催化体系，避免采用昂贵的漆酶制剂和人工合成介体所带来的高成本以及二次环境污染问题。进一步研究漆酶/天然介体系统对土壤中典型有机污染物的降解动力学，并对土壤复合有机污染物进行原位降解研究。本项目的研究工作将进一步提升秸秆还田技术，增加土壤肥力，加速土壤中农药、多环芳烃等污染有机物的降解，为改善生态环境，促进农业生产可持续发展探寻出一条经济、环保、高效的新途径。

针对土壤污染以及秸秆利用方面所面临的严峻挑战，本项目对重组里氏木霉转化子的发酵性能、遗传稳定性及其在秸秆原料上的生长动力学、底物降解动力学和产酶（漆酶、纤维素酶、木聚糖酶等）动力学进行了深入研究。研究结果表明：重组里氏木霉不但可以产生高活力的纤维素酶和木聚糖酶，还可以产生漆酶，在快速降解秸秆纤维素、半纤维素的同时，也可以降解秸秆木质素。而木质素降解的一些中间产物如香草醛、丁香醛、丁香酸等可作为漆酶催化反应的天然介体，促进漆酶对土壤中有机污染物的催化降解，这样就可避免采用昂贵的漆酶制剂和人工合成介体所带来的高成本以及二次环境污染问题。. 以重组里氏木霉为核心，并选择黑曲霉及白腐真菌为辅助菌种，成功构建了既能快速降解秸秆，又可高产漆酶、促进土壤有机污染物降解修复的新型秸秆降解剂。在此基础上，进一步对秸秆快速降解和有机物污染土壤生物修复的耦合过程进行了深入研究。将秸秆平铺在污染土壤上，接入新型秸秆降解剂后第12天，秸秆基质中漆酶活力、纤维素酶（滤纸酶）活力和木聚糖酶活力分别可达到25.31 IU/g、240.44 IU/g 和4537.16 IU/g；秸秆纤维素、半纤维素和木质素的降解率分别达到了75.40 %、77.33 %和32.35 %，秸秆失重率达60.19 %。土壤中有机污染物在此过程中也可得到有效降解（其中：对兽用抗生素金霉素和土霉素的降解率分别可达95.7 % 和93.4 %，对壬基酚和双酚A的降解率分别为95.6%和90.1 %, 毒死蜱和2,4,5-三氯酚的降解率分别达到了62.3 %和65.2 %）。. 本项目的研究工作将秸秆快速降解过程与土壤有机污染物的修复过程有机结合，在秸秆快速降解还田过程中实现土壤有机污染物的原位降解修复，所取得的研究成果将进一步提升秸秆还田技术，增加土壤肥力，加速土壤中农药、抗生素等有机污染物的降解，促进农业生产可持续发展。