Temporal Variations in the Abundance and Composition of Biofilm Communities Colonizing Drinking Water Distribution Pipes

Abstract

Pipes that transport drinking water through municipal drinking water distribution systems (DWDS) are challenging habitats for microorganisms. Distribution networks are dark, oligotrophic and contain disinfectants; yet microbes frequently form biofilms attached to interior surfaces of DWDS pipes. Relatively little is known about the species composition and ecology of these biofilms due to challenges associated with sample acquisition from actual DWDS. We report the analysis of biofilms from five pipe samples collected from the same region of a DWDS in Florida, USA, over an 18 month period between February 2011 and August 2012. The bacterial abundance and composition of biofilm communities within the pipes were analyzed by heterotrophic plate counts and tag pyrosequencing of 16S rRNA genes, respectively. Bacterial numbers varied significantly based on sampling date and were positively correlated with water temperature and the concentration of nitrate. However, there was no significant relationship between the concentration of disinfectant in the drinking water (monochloramine) and the abundance of bacteria within the biofilms. Pyrosequencing analysis identified a total of 677 operational taxonomic units (OTUs) (3% distance) within the biofilms but indicated that community diversity was low and varied between sampling dates. Biofilms were dominated by a few taxa, specifically Methylomonas, Acinetobacter, Mycobacterium, and Xanthomonadaceae, and the dominant taxa within the biofilms varied dramatically between sampling times. The drinking water characteristics most strongly correlated with bacterial community composition were concentrations of nitrate, ammonium, total chlorine and monochloramine, as well as alkalinity and hardness. Biofilms from the sampling date with the highest nitrate concentration were the most abundant and diverse and were dominated by Acinetobacter.

Pyrosequencing analysis of bacterial diversity in dental unit waterlines

“…Mycobacterium occurrence in IW was not surprising as it was recently reported by Kelly and collaborators to be among the dominant taxa of biofilms in drinking water distribution pipes with concentrations up to 14% (Holinger et al, 2014;Kelly et al, 2014), in accordance with a number of parameters such as nitrate, ammonium, total chlorine and monochloramine concentrations. In contrast, the high relative abundance of Propionibacterium highlighted in IW was not expected since the bacteria related to this genus are usually found on the skin (Scharschmidt and Fischbach, 2013).…”

Inflammatory responses and potencies of various lipopolysaccharides from bacteria and cyanobacteria in aquatic environments and water supply systems

“…including A. lwoffii are known not just as opportunistic pathogens but also ubiquitous habitant in biofilm in water distribution systems. (Scott and Pepper, 2010;Vaz-Moreira et al, 2013;Kelly et al, 2014). This result suggests that inflammatory potency can increase with the regrowth of Acinetobacter sp.…”

Assessment of the influence of intrinsic environmental and geographical factors on the bacterial ecology of pit latrines

“…At the family level, one taxon that showed significantly higher proportional abundances in Vietnamese pit latrines compared with those in Tanzania was the Xanthomonadaceae, typically characterized as environmental organisms which are found in soil and water, as well as plant tissues (Arrieta-Ortiz et al, 2013;Hui et al, 2014;Kelly et al, 2014). Recent studies have shown degradation properties for organisms from this family (Cea et al, 2010;Liu et al, 2011).…”