The bacterial community of biofilms in drinking water distribution systems (DWDS) with various water sources
has been rarely reported. In this research, biofilms were sampled at three points (A, B, and C) during the river
water source phase (phase I), the interim period (phase II) and the reservoir water source phase (phase III),
and the biofilm community was determined using the 454-pyrosequencing method. Results showed that microbial
diversity declined in phase II but increased in phase III. The primary phylumwas Proteobacteria during three
phases, while the dominant class at points A and B was Betaproteobacteria (N49%) during all phases, but that
changed to Holophagae in phase II (62.7%) and Actinobacteria in phase III (35.6%) for point C, which was closely
related to its water quality.More remarkable community shift was found at the genus level. In addition, analysis
results showed that water quality could significantly affect microbial diversity together,while the nutrient composition
(e.g. C/N ration) of the water environment might determine the microbial community. Furthermore,
Mycobacterium spp. and Pseudomonas spp. were detected in the biofilm, which should give rise to attention.
This study revealed that water source switching produced substantial impact on the biofilm community.