Ahn Mi-Youn, Dec Jerzy, Kim Jang-Eok, Bollag Jean-Marc
Laboratory of Soil Biochemistry, Pennsylvania State University, 129 Land and Water, University Park, PA 16802, USA.
J Environ Qual. 2002 Sep-Oct;31(5):1509-15. doi: 10.2134/jeq2002.1509.
Enzyme treatment is currently considered for remediation of terrestrial systems polluted with organic compounds. In this study, two soils from Pennsylvania with 2.8 or 7.4% organic matter contents (Soils 1 and 2, respectively) were amended with 14C-labeled 2,4-dichlorophenol (2,4-DCP) and incubated with a laccase from Trametes villosa (free or immobilized on montmorillonite). 2,4-DCP was either transformed to methanol-soluble polymeric products (11-32%) or covalently bound to soil organic matter (53-85%); unaltered 2,4-DCP could be recovered from soil by methanol extraction (0-38%) at the completion of a 14-d incubation period. In Soil 1, both free and immobilized laccase removed 100% of 2,4-DCP without regard for moisture conditions. In Soil 2, immobilized laccase removed more 2,4-DCP (about 95%, regardless of moisture conditions) than free enzyme (55, 75, and 90% at 30, 55, and 100% of maximum water-holding capacity, respectively). Binding of 2,4-DCP in the humin fraction was nearly the same for free and immobilized laccase. More 2,4-DCP, however, was bound to humic and fulvic acids in the presence of immobilized laccase than in the presence of free laccase. In general, immobilized laccase performed better than free laccase. However, for practical applications, the higher activity of immobilized laccase is offset by a 23% loss in enzyme activity during immobilization, which approximates the 30% increase in free laccase needed to achieve the same level of remediation. Furthermore, immobilized laccase is more costly than free T. villosa laccase.
目前，酶处理被认为是修复受有机化合物污染的陆地系统的一种方法。在本研究中，用14C标记的2,4 - 二氯苯酚（2,4 - DCP）对宾夕法尼亚州的两种土壤（分别为土壤1和土壤2，有机质含量分别为2.8%或7.4%）进行改良，并与绒毛栓菌漆酶（游离或固定在蒙脱石上）一起培养。2,4 - DCP要么转化为甲醇可溶的聚合产物（11 - 32%），要么与土壤有机质共价结合（53 - 85%）；在14天的培养期结束时，未改变的2,4 - DCP可通过甲醇萃取从土壤中回收（0 - 38%）。在土壤1中，无论水分条件如何，游离和固定化漆酶都能去除100%的2,4 - DCP。在土壤2中，固定化漆酶去除的2,4 - DCP比游离酶更多（无论水分条件如何，约为95%），游离酶在最大持水量的30%、55%和100%时分别去除55%、75%和90%。游离和固定化漆酶使2,4 - DCP在腐殖质部分的结合情况几乎相同。然而，与游离漆酶相比，固定化漆酶存在时更多的2,4 - DCP与腐殖酸和富里酸结合。总体而言，固定化漆酶的性能优于游离漆酶。然而，对于实际应用，固定化漆酶较高的活性被固定过程中23%的酶活性损失所抵消，这近似于达到相同修复水平所需的游离漆酶增加30%的活性。此外，固定化漆酶比游离绒毛栓菌漆酶成本更高。
