粘土矿物固定化微生物对土壤中阿特拉津的降解研究

以粘土矿物为载体,采用吸附挂膜法对已筛选的阿特拉津降解菌株进行固定化,并应用固定化微生物降解土壤中的阿特拉津。结果表明,该菌株在粘土矿物上生长良好,根据菌种生理生化特性、环境扫描电镜图片以及16S rDNA基因的相似性分析初步鉴定该菌株为Ochrobactrum sp.。接种降解菌能明显加快阿特拉津在土壤中的降解速率,粘土矿物固定化微生物的降解效果要明显优于游离菌,粘土矿物粒径越小,固定化微生物的降解效果越好,纳米粘土矿物固定化微生物的降解效果要好于原粘土矿物。用一级动力学方程描述阿特拉津在土壤中的降解过程,不同土壤中阿特拉津的降解速率不同。阿特拉津在红壤、砂姜黑土、黄褐土中的降解半衰期（t1/2）分别为36.9、49.1、55.0 d,投加纳米蒙脱石固定化降解菌后的半衰期则分别为16.3、25.3、21.7 d。

Biodegradation of Atrazine in Soils by Clay Minerals Immobilized a Degradation Bacterium

Biodegradation of atrazine in soils by clay minerals immobilized a degradation bacterium were studied. The bacterium which was isolated from activated sludge by enrichment using atrazine as sole source of carbon and nitrogen was preliminarily identified as Ochroboctrum sp., according to its physiological-biochemical characteristics, photos of ESEM and the similarity analysis of its 16S rDNA gene sequence. The strains growed well on clay minerals, and reached logarithmic phase at 48 h. The degradation rate of atrazine was larger signifieally when adding degradation bacteria into soils. The biodegradation capacity by immobilized microorganism on clay minerals was improved compared with free microorganism. The smaller the particle size of clay minerals, the more the biodegradation of atrazine. The effect of immobilized nano-elay minerals was better than corresponding clays. The degradation of atrazine were 42.47%, 46.19%, 56.31% respectively, after adding free microorganism into vertisol, alfisol and red soil on 28 d. When adding immobilized microorganism by montmorillonite, nano-montmorillonite, the degradation ofatrazine were 52.16%, 63.97% in vertisol, 59.28%, 63.91% in alfisol, and 68.03%, 76.59% in red soil. The degradation of atrazine in the soil without microorganism was 29.16% in vertisol, 30.63% in alfisol, 41.47% in red soil. Atrazine degradation in soils could be described by first-order kinetic equation. The effect of degradation varied from different soils. The（t1/2）of atrazine was 36.9 d in red soil, 49.1 d in vertisol, and 55.0 d in alfisol without microorganism. When adding immobilized microorganism by nano-montmorillonite, half-life was 16.3 d, 25.3 d, 21.7 d respectively.