Comparison of biofilm ecology supporting growth of individual Naegleria species in a drinking water distribution system

Abstract

Free-living amoebae (FLA) are common components of microbial communities in drinking water distribution systems (DWDS). FLA are of clinical importance both as pathogens and as reservoirs for bacterial pathogens, so identifying the conditions promoting amoebae colonisation of DWDSs is an important public health concern for water utilities. We used high-throughput amplicon sequencing to compare eukaryotic and bacterial communities associated with DWDS biofilms supporting distinct FLA species (Naegleria fowleri, N. lovaniensis or Vermamoeba sp.) at sites with similar physical/chemical conditions. Eukaryote and bacterial communities were characteristics of different FLA species presence, and biofilms supporting Naegleria growth had higher bacterial richness and higher abundance of Proteobacteria, Bacteroidetes (bacteria), Nematoda and Rotifera (eukaryota). The eukaryotic community in the biofilms had the greatest difference in relation to the presence of N. fowleri, while the bacterial community identified individual bacterial families associated with the presence of different Naegleria species. Our results demonstrate that ecogenomics data provide a powerful tool for studying the microbial and meiobiotal content of biofilms, and, in these samples can effectively discriminate biofilm communities supporting pathogenic N. fowleri. The identification of microbial species associated with N. fowleri could further be used in the management and control of N. fowleri in DWDS.

Whole metagenome sequencing of chlorinated drinking water distribution systems

“…Eukaryotes are part of the ecological network of these engineered systems and consequently they can affect the quality and safety of the water. There are few studies based on eukaryotes in DWDS and those have been mainly focused in the parasitic protozoan Cryptosporidium and Giardia, or in planktonic amoeba studies 24,40 and to some extent fungi, mainly Ascomycota. 41,42 One of the few drinking water studies that reports the mixed presence of different eukaryotes in water from a desalination plant is that of Belila et al 39 The authors reported that uncultured fungi were the major group of eukaryotes, followed by Chordata and Arthropoda.…”

“…A step further in the use of molecular methods to understand DWDS is shotgun metagenomics, the use of DNA-based whole metagenomic analyses can define both taxonomy and potential function (presence of gene pools and expression when sequencing RNA) of complex microbial communities, providing greater insights into the processes and pathways of whole communities and their ecology. 22 The whole metagenome sequencing analysis presented here includes the study of eukaryotes, organisms that despite their proven presence in these systems 23 have been long ignored in most microbial studies in DWDS, with the exception of amoebas 24,25 and the protozoa Cryptosporidium. 26 In order to understand dynamics in DWDS and how they work as an ecosystem, we need to consider all interactions including those between eukaryotes and prokaryotes which are important for the maintenance of ecological processes.…”

A comparative ‘omics approach to candidate pathogenicity factor discovery in the brain-eating amoebaNaegleria fowleri

“…Naegleria fowleri is an opportunistic pathogen of humans and animals, causing primary amoebic meningoencephalitis (PAM), and killing up to 97% of those infected, usually within two weeks (Carter, 1970). It is found in warm freshwaters around the world and drinking water distribution systems (DWDS) (Morgan et al, 2016; Puzon et al, 2009; Puzon et al, 2017) with N. fowleri -colonized DWDSs linked to deaths in Pakistan (Kazi and Riaz, 2013; Mahmood, 2015; Naqvi et al, 2016), Australia (Dorsch, 1982), and the USA (Cope et al, 2015; Yoder et al, 2012). Infection occurs when contaminated water enters the nose.…”

Environmental abiotic and biotic factors affecting the distribution and abundance ofNaegleria fowleri

“… 2015 ; Puzon et al . 2017 ), it is unlikely that sunlight plays a role in determining amoebae presence, but no studies have investigated whether sunlight impacts N. fowleri proliferation, life stage regulation or microbial prey communities.…”

“… 2016 ; Puzon et al . 2017 ). Because chlorine levels in drinking water decreased with distance from the chlorine treatment point, distance from the chlorine treatment point was positively correlated with N. fowleri presence (Morgan et al .…”