Potential of extra cellular enzymes in remediation of polluted soils: a review

The use of microorganisms (bioremediation) and plants (phytoremediation) to remediate polluted environments is a promising and growing area of environmental biotechnology. The first productive step in cell-transformation of xenobiotic substances, including recalcitrant and even plastic materials, is usually catalyzed by ecto and extra cellular enzymes, released by the cells in their nearby environment. Extra cellular enzymes include a large range of oxidoreductases and hydrolases. Both these enzymes may explicate a degradative function and transform polymeric substances into partially degraded or oxidized products that can be easily up-taken by cells. The presence of the whole cell and its metabolic pathways to be completed are required. The use of extra cellular and/or cell-free enzymes has been also proposed as an innovative remediation technique. They can offer some advantages over the use of microbial cells. Several bottlenecks, however, still restrict their practical application in the recovery of polluted environments. A brief survey of many aspects dealing with the characteristics and potential abilities of both cell-present- and cell-free extra cellular enzymes is provided. The feasibility of their application for bioremediation of polluted soils has been briefly addressed, as well. (C) 2004 Elsevier Inc. All rights reserved.