Metagenome analyses of corroded concrete wastewater pipe biofilms reveal a complex microbial system

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.

Metagenome Survey of a Multispecies and Alga-Associated Biofilm Revealed Key Elements of Bacterial-Algal Interactions in Photobioreactors

“…The earliest studies dealt with the acid mine drainage biofilm (95) and a drinking water biofilm (96). More recently, studies have addressed microbial biofilm metagenomes of hydrothermal vent chimneys, biofilms on concrete water pipes, and an extremely acidophilic sulfur-oxidizing biofilm (97)(98)(99). Although not all studies have been listed here, it is evident that many different biotic and abiotic factors shape each of these communities and that each community clearly differs in its phylogenetic structure and genomic-information content.…”

Characteristics of biofilms and iron corrosion scales with ground and surface waters in drinking water distribution systems

“…For corrosion scales with biofilms, samples were collected with a sterile metal spatula scraping approximately 3 cm 2 surface area from 6 different locations on each pipe [29]. Then, the samples from the same pipe were mixed and lyophilized for further characterization.…”

The dual role of microbes in corrosion

“…Modern metagenomics approaches have only scarcely been applied in corrosion studies. Gomez-Alvarez et al (2012) analyzed the microbial community in corroded wastewater pipes and they were able to relate the corrosion to sulfur and nitrogen pathways. Sampling is an important issue, because in oil industry most samples are water samples and they do not represent the microbial community attached to the pipeline walls (Skovhus et al, 2011).…”