土壤特性对微生物迁移趋触效应的影响研究

微生物的迁移行为对污染土壤的生物修复至关重要。微生物能够沿着液相中和固相上污染物的正向浓度梯度进行运动，达到降解污染物的目的，在液相中的运动称为趋化效应，有利于溶解态污染物的降解；在固相上的运动称为趋触效应，有利于吸附态污染物的降解。前人已经对趋化效应做了大量研究，然而鲜有关于趋触效应的报道。申请者的前期研究表明，有机污染物在土壤表面的不均匀吸附会导致微生物趋触效应的形成，增加其在固相表面的保持和迁移，该效应在渗透性低、有机污染物吸附力强的土壤中更为明显。因此，本研究旨在探明主要土壤特性和条件对趋触效应的影响。具体而言，我们计划选择荧光假单胞菌为微生物代表，萘为有机污染物代表，利用实时生物成像系统原位观测梯度扩散实验和土柱迁移实验过程中土壤有机质、胶体及水分对萘的固液分配和假单胞菌的趋触效应的影响。本研究的顺利完成将为污染土壤的微生物修复提供新的机制和手段。

Understanding bacterial transport in porous media is crucial in successful implementation of soil bioremediation. Directional motion toward contaminants along a concentration gradient in aqueous phase is called chemotaxis, which is beneficial to the degradation of dissolved pollutants. While migration toward concentrated contaminants along an immobilized solid surface is called haptotaxis, which is beneficial to the degradation of adsorbed pollutants. Plenty of researches have been conducted on chemotaxis, whereas few on haptotaxis. The applicant's previous research has shown that the uneven distribution of organic pollutants adsorbed on solid phase would trigger haptotaxis, increasing bacterial retention and transport along the solid surface. In addition, haptotaxis would be more significant than chemotaxis in soils with low permeability or high affinity of organic pollutants. Thus, this proposed research will focus on the effects of soil characteristics on haptotaxis, with Pseudomonas fluorescens being selected as the representative of microorganisms and naphthalene being selected as the representative of contaminants. The effects of soil organic matter, colloid and water saturation on the solid-liquid distribution of naphthalene and haptotaxis will be investigated by high-resolution real-time bioluminescent imaging through gradient diffusion experiments and column experiments in suit. This research will generate novel mechanisms and methods to microbial remediation of contaminated soil.