Microbial Characterization of Excessive Growing Biofilm in Sewer Lines Using Molecular Technique

For elucidating excessive growth of biofilm that subsequently leads to the clogging problem in a small town's sewer lines of Wisconsin, the FISH method was employed. At the beginning of the simulated experiments, ${\beta}$-subclass proteobacteria prevailed in runs fed with industrial wastewater, while ${\gamma}$-subclass proteobacteria dominated in runs with domestic wastewater. However, the bacterial community structure changed significantly over six weeks; Cytophaga-Flavobacterium (CF)­group bacteria dominated in most runs fed with the small town's wastewater regardless of their source, while CF-group decreased strongly in run fed with domestic sewage from another city (Madison). It was also microscopically confirmed that most of those clogging materials was toilet tissue, which in turn may lead to vigorous growth of cellulose-degrading CF-group bacteria. This dominant presence of CF-group bacteria in the small town's sewer indicates that the main constituent of biofilm, toilet tissue (cellulose) in sewage, might have induced the unique pattern of their microbial community structure. Therefore, it suggests that molecular technique is useful for monitoring the clogging problems in sewer lines.