The molecular characterization of raw septic tank sewage in the region under study was evaluated using 16S rRNA denaturing gradient gel electrophoresis (DGGE). Raw effluent samples from three septic tanks in the Delta and Edo States region of Nigeria was collected between November 2018 and January 2019 for testing. A composite sample was formed from the three samples collected. The raw sewage sample was sequenced for genomic DNA using Norgen DNA extraction kit to determine the microorganisms present in raw sewage sample. Gene sequence analysis revealed the presence of Methanococcus methanococcus 288171278, Deferribacteres bacterium 291088137, Flavobacteria bacterium 308271278, Bacteroides dorei 671713918, Clostridium difficile 115249003, Kuenenia stuttgartiensis 91203347, Methanosarcina bankeri 827396966, Methanococcus maripaludis 4505076 and Methanobacterium formicicum 693274837, and Desulfitobacterium dichloroeliminans 430782295. The phylogram of the different isolates shows that methane producing bacteria were 7 out of the 13 bacteria isolated; representing 53.8% of the total species occurrence in the sample.
Key words: Gene sequence, bacteria, raw sewage, septic tank.