A natural forest soil was contaminated artificially with mixture of tetraethyleneglycol (TEG), 1-amino-2-propanol (APOL), diethylene glycolmonomethylether (DGMME), diethyleneglycolmonoethylether (DGMEE), tetrahydrothiophene-1, 1-dioxide (THT), 1-methyl-2-pyrrolidinone (MP), and tetramethylammoniumhydroxide (TMAH) but was not for control test. Both contaminated and uncontaminated soil microcosms were cultivated at 20oC for 10 weeks under humid conditions, which were named the xenobio microcosm (XM) and conventional microcosm (CM), respectively. DNA was directly extracted from both the microcosms every 2 weeks from 2nd to 14th week during incubation. Temperature gradient gel electrophoresis (TGGE) patterns for variable region (V3) of 16S-rDNA amplified with DNA extracted from the XM were changed more variably than those from the IM. The mineralization of xenobiotics in the XM was analyzed every 2 weeks. TEG, DGMME, DGMEE and TMAH were mineralized completely in 16 weeks, and APOL and MP were in 20 weeks. However, THT was not mineralized completely for 20 weeks. TEG-, APOL-, DGMME-, DGMEE-, THT-, MP-, TMAH-degrading bacterium isolated from the XM was Burkholderia sp. SK100101, Burkholderia sp. SK100102, Arthrobacter sp. SK100103, Dyella sp. SK100104, Phyllobacterium sp. SK100105, Burkholderia sp. SK100106, Acidovorax sp. SK100107, respectively. These results indicated that the bacterial species that had not been exposed to the specific xenobiotics used in this research could adapt metabolically to the xenobiotics in 14 weeks.