Legionella community diversity and dynamics in activated sludge systems of wastewater treatment plants: Are they transient visitors or residents?

Abstract: The environmental source of Legionella infections, which can cause severe pneumonia, often remains unidentified. Increasing global incidences highlight the need to explore additional infection sources. Wastewater treatment plants (WWTPs) have been linked to Legionella outbreaks. However, it is unclear how their populations change dynamically within these systems and which Legionella spp. occur in WWTPs. We sampled five aerobic activated sludge (AS) systems, including influent entering the AS system, AS and treated wastewater samples, from industrial WWTPs with conditions favourable for Legionella spp. occurrence, at five different time points. We assessed Legionella diversity by sequencing their V3 and V4 regions of the 16S rRNA gene and calculating the alpha-, beta-, and zeta-diversity. Concentrations were measured using qPCR and cultivation method. Mass balance analysis was conducted, assuming no net growth. The results of this study can be found in: link