低分子量有机配体对黏粒矿物吸附苏云金芽孢杆菌的影响

土壤是微生物的理想栖息地,土壤微生物群落组成复杂,数量巨大。1g土壤中可能栖息着上百亿个微生物,其中细菌可达1010个1]。约80%～90%的土壤微生物寄居于土壤固相表面,如黏土矿物、金属氧化物或有机质表面2]。细菌与矿物间的相互作用在土壤污染物转化与降解、团聚体形成3]、矿物风化4-6]及病原菌运移7-8]等诸多过程起着关键作用。

Effects of low-molecular-weight organic ligands on adsorption of Bacillus thuringiensis by clay minerals

Adsorption of Bacillus thuringiensis on kaolinite, montmorillonite and goethite was studied in the presence of organic ligands. Acetate, oxalate, tartrate and citrate significantly inhibited the adsorption of B. thuringiensis by three minerals in a broad range of ligand concentrations. The highest efficiencies of the four ligands in blocking the adsorption of B. thuringiensis on goethite, kaolinite and montmorillonite were 24-84%, 12-54% and 9-36%, respectively. The ability of organic ligands in prohibiting the binding of B. thuringiensis cells to the minerals followed the sequence of citrate > tartrate > oxalate > acetate. The significant suppressive effects on B. thuringiensis adsorption were attributed to the increased negative charges by adsorbed ligands and the competition of ligands with bacterial surface groups for binding sites. The inhibitive effects on B. thuringiensis adsorption by organic ligands were also dependent on the steric hindrance of the molecules. The results quantitively elucidated that low-molecular-weight organic ligands have profound influences on the adsorption of bacteria by clay minerals in soils, especially in the rhizosphere. The study is of fundamental importance in understanding the interactions of bacteria with minerals in soils and associated environments.