NOVELTY - Method of enriching bacteria in a target soil capable of decomposing organic contaminants, involves mixing a fragmented porous material, the material having number of micropores and having a greater adsorptivity, into the soil which the bacteria inhabit to form an enrichment soil layer, and circulating through the layer an inorganic salt medium, thus enriching the bacteria in the fragmented porous material.    USE - The method is useful for isolating bacteria, by inoculating a fragmented porous material in which the bacteria have already been enriched into a new fragmented porous material to form an enrichment layer consisting of the fragmented porous material only, and repeatedly carrying out number of times an operation of enriching the bacteria in new fragmented porous material as well as by circulating through the enrichment layer an inorganic salt medium containing a carbon source and a nitrogen source, thus increasing a degree of purity and enrichment of the bacteria, for speedy isolation of the enriched bacteria (claimed). The method is also useful for treating soil polluted by organic contaminants, such as agricultural chemicals, particularly to prevent groundwater pollution caused by agricultural chemicals in the soil.    ADVANTAGE - The method drastically reduces the time required for enriching or isolating the decomposing bacteria. The method is a high speed technique that enhances the speed of enrichment of decomposing bacteria and the isolation of the same from the soil. This method is effective when artificial microhabitats containing enriched decomposing bacteria are used in farms and golf courses as a material for prevention of groundwater pollution, realizing a more efficient groundwater control capability.    DETAILED DESCRIPTION - Method of enriching bacteria in a target soil capable of decomposing organic contaminants, involves mixing a fragmented porous material, the material having a number of micropores sufficient to provide a specific surface area greater than 50 m2/g and smaller than 600 m2/g and having a greater adsorptivity for absorbing the organic contaminants than the target soil, into the soil which the bacteria inhabit to form an enrichment soil layer, and circulating through the enrichment soil layer an inorganic salt medium containing carbon and nitrogen sources, the carbon and nitrogen sources is formed by only the organic contaminants to be decomposed, thus enriching the bacteria in the fragmented porous material.    DESCRIPTION OF DRAWING(S) - The figure shows a device used in enriching decomposing bacteria.