Community shift of biofilms developed in a full-scale drinking water distribution system switching from different water sources

摘要

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 micro-bial diversity declined in phase Ⅱ but increased in phase Ⅲ. The primary phylum was Proteobacteria during three phases, while the dominant class at points A and B was Betaproteobacteria (＞49%) 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.