Distribution and population structure characteristics of microorganisms in urban sewage system.

The sewage system functions as an important public infrastructure. The survived microbial population inside the sewage system plays an important role in the biochemical process during wastewater transportation within the system. The study aims to investigate the microbial communities spatial distribution inside manholes and sewage pipes by using the massive parallel 454 pyrosequencing combined with denaturing gradient gel electrophoresis of V1-V3 regions of 16S rRNA. The microbial structure, distribution characteristic, taxonomic composition analysis, and compositional overlaps of the microbial community both were conducted. The result indicated that the changes in microbial diversity exhibited a consistent trend with average dehydrogenase activity. Proteobacteria, Firmicutes, and Anaerolineae were the dominant bacteria in the sewage system. The microbial community exhibited distinguishing characteristics in comparison with fecal, surface water, and wastewater treatment process. Parachlamydia acanthamoebae, Zymophilus paucivorans, and uncultured Epsilon proteobacterium were mainly found at the upper position of the manhole, while Microbacterium sp. was mainly found at the lower position. Longilinea, Georgenia, and Desulforhabdus were mainly observed in the sewage pipe. The microbial bacteria that survived in the anaerobic environment (i.e., sulfate reduction bacteria groups) exhibited a significant positive relationship with anaerobic crucial environmental factors in the redundancy analysis.