What's lurking in your sink drain? - Understanding microbial community dynamics in communal sink drains.

There is greater interest than ever in studying microorganisms in the built environment motivated by the fact that people in the developed world spend approximately 90% of their times in buildings [1]. Recent evidence suggests that the majority of microorganisms that we come across in our lifetime are those that occupy the built environment [2]. Due to the increasing trend towards an indoor lifestyle, and the significant roles the indoor microorganisms may play on human health, it is imperative that we develop a greater understanding of the factors that shape microbial communities in the built environment. Despite the interest and increasing amount of knowledge being acquired in microbial communities in buildings [3], very little is known about microorganisms that occupy sink drains and pipes, especially those in communal or public areas. This is possibly due to the general perception that sinks constitute a one-way traffic of waste, i.e. what goes into sink drains and pipes cannot "crawl" back out. A recent study conducted by collaborators of the supervisory team has, however, shown that not only can microorganisms grow out from the bottom of a sink pipe to the top of a drain at an alarming rate of one inch per day, they have shown that bacteria, having reached the top of the drain, can be dispersed out of the sink and travel up to a metre by the physical mechanistic action of the running water from the tap [4]. While a number of studies have suggested that sinks are an ideal niche for human pathogens to grow and exchange genes such as antimicrobial resistance [5], it has been challenging to identify preventative measures so far. Disturbingly, in hospitals the use of bleach or even replacing the plumbing has been shown to have minimal long term effects on the microbiome and resistance genes, which can regrow and colonise within days. This has significant implications in terms of how sinks in communal areas may play a role in disseminating pathogens and resistance genes.
In this project, we will address significant knowledge gaps in the ecology and evolution of sink microbiome, and how it is influenced by sink usage/practice with a key aim to study the resilience and persistence of the communities and species. More specifically we will (1) characterise microbial communities in communal sink drains and pipes in both clinical and non-clinical settings; (2) evaluate the ecological and evolutionary processes and factors that drive their community dynamics; (3) and the effect sink usage/practices have on resilience of the community (e.g. the use of antibacterial soap, cleaning agents on the community). We will leverage various techniques including culture-based methods and the use of modern high-throughput DNA sequencing for characterisation of microbial communities including both short and long sequencing technologies. We will also undertake various manipulated studies to understand how the sink drain microbial community shifts under a set of varying environmental conditions, with the aim of identifying preventative measures.

[1] Klepeis et al (2001), J. Expo. Anal. Environ. Epidemiol, 11, p231
[2] Dunn et al (2013), PLoS One, 8(5): e64133
[3] Flores et al (2011), PLoS One, 6(11):e28132
[4] Kotay et al (2017), Appl. Environ.Microbiol., 83:8
[5] Brooks et al (2017), Nat. Comm., 8:1814