Abstract
BackgroundConcrete corrosion of wastewater collection systems is a significant cause of deterioration and premature collapse. Failure to adequately address the deteriorating infrastructure networks threatens our environment, public health, and safety. Analysis of whole-metagenome pyrosequencing data and 16S rRNA gene clone libraries was used to determine microbial composition and functional genes associated with biomass harvested from crown (top) and invert (bottom) sections of a corroded wastewater pipe.ResultsTaxonomic and functional analysis demonstrated that approximately 90% of the total diversity was associated with the phyla Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. The top (TP) and bottom pipe (BP) communities were different in composition, with some of the differences attributed to the abundance of sulfide-oxidizing and sulfate-reducing bacteria. Additionally, human fecal bacteria were more abundant in the BP communities. Among the functional categories, proteins involved in sulfur and nitrogen metabolism showed the most significant differences between biofilms. There was also an enrichment of genes associated with heavy metal resistance, virulence (protein secretion systems) and stress response in the TP biofilm, while a higher number of genes related to motility and chemotaxis were identified in the BP biofilm. Both biofilms contain a high number of genes associated with resistance to antibiotics and toxic compounds subsystems.ConclusionsThe function potential of wastewater biofilms was highly diverse with level of COG diversity similar to that described for soil. On the basis of the metagenomic data, some factors that may contribute to niche differentiation were pH, aerobic conditions and availability of substrate, such as nitrogen and sulfur. The results from this study will help us better understand the genetic network and functional capability of microbial members of wastewater concrete biofilms.
Highlights
Concrete corrosion of wastewater collection systems is a significant cause of deterioration and premature collapse
Metagenome library construction In this study, we analyzed the microbial communities of biofilms established on the top (TP) and bottom (BP) of a corroded wastewater concrete pipe
We identified and removed artificially replicated reads, which represented a total of 14% and 12% of sequences from the TP and bottom pipe (BP) metagenomes, respectively
Summary
Concrete corrosion of wastewater collection systems is a significant cause of deterioration and premature collapse. Concrete corrosion of wastewater collection systems is a significant cause of deterioration and premature failure. In wastewater collection systems microbial-induced concrete corrosion (MICC) may occur in areas under higher concentrations of hydrogen sulfide (H2S) [3,4,5]. The primary source of sulfur is sulfate (SO42-) which can be reduced by sulfate-reducing bacteria (SRB) to hydrogen sulfide (H2S) under anaerobic conditions. H2S is transferred across the air-water interface to the sewer atmosphere where chemoautotrophic bacteria on the pipe surface, including sulfide-oxidizing bacteria (SOB), convert the H2S to biogenic sulfuric acid (H2SO4). Biogenic sulfuric acid (H2SO4) can be generated by various microbial species [6,7,8,9]
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