In-situ features of LNA and HNA bacteria in branch ends of drinking water distribution systems

The knowledge of bacteria with low or high nucleic acid (LNA or HNA, respectively) content was relatively limited in drinking water distribution systems (DWDSs). In the present study, LNA and HNA bacterial growth characteristics and effect of water physicochemical properties on these two subgroups were analyzed at the branch ends of a DWDS. The results showed that LNA bacteria were in the majority in tap water (67.2% +/- 16.6%) and the specific growth rate (0.469 +/- 0.022/d) was lower than that of HNA bacteria (1.116 +/- 0.195/d). LNA and HNA bacteria showed different responses to water physicochemical properties. The LNA bacteria dominated the microbial community under relatively high conductivity conditions, and the HNA bacteria were predominant in high turbidity or alkalescence environments. The LNA bacteria growth rate was positively correlated to the assimilable organic carbon concentration. In addition, multivariate ordination illustrated that there were clear variances in water quality among outlets, which could result from different pipeline distances and hydraulic conditions.