TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: In (M1), the target substance is phthalate compound. The gel electrophoresis is temperature-gradient gel electrophoresis (TGGE) or denaturant concentration-gradient gel electrophoresis (DGGE). The nucleic acid is 16S rRNA. EXAMPLE - Acquiring the nucleic acid of the microorganisms which inhabit organism property sludge was as follows. The granule sludge collected from the beer brewery was prepared for a upward-flow anaerobic sludge floor (UASB) waste-water-treatment apparatus as organism property sludge. The 2.7 liter was supplied to the waste-water-treatment apparatus. Then, the waste water which made a phthalic acid compound the only source of a carbon was supplied continuously. The density concentration of the phthalic acid compound in a waste water and a treated water was measured by the high performance liquid chromatography (HPLC). The waste water treatment apparatus was worked for two months (35-37 degrees C, pH 6.7-7), and about 5 ml of granule sludge was collected at intervals of one month. Thus the nucleic acid (RNA) of the microorganisms contained in the sludge collected with time was acquired. cDNA was synthesized by making acquired RNA into a template, related to the specific region of 16S rRNA in acquired RNA using primers GC-PRBA338f and PRUN518r, where the primer which had a base sequence originating in 16S rRNA. The degradation activity of a phthalic acid compound was evaluated. The DNA fragment obtained was subjected to denaturant concentration-gradient gel electrophoresis (DGGE) and the band of DNA was detected. The electropherogram obtained by electrophoresing was analyzed. The result of the electrophoresis of the sludge origin sample which opened the interval of one month showed the diversity of the intrinsic producing bacteria. Each DNA band corresponded to a respective intrinsic species, by comparing the appearance pattern of a band and investigating a bacteria species which had phthalic acid degradation activity in a sludge disposal was performed.