Benthic Biofilm Bacterial Communities and Their Linkage with Water-Soluble Organic Matter in Effluent Receivers.

Longfei Wang,Wenlong Zhang,Yutao Wang,Lihua Niu,Nuzahat Habibul,Huanjun Zhang,Yi Li

doi:10.3390/ijerph19041994

Abstract

Benthic biofilms are pioneering microbial aggregates responding to effluent discharge from wastewater treatment plants (WWTPs). However, knowledge of the characteristics and linkage of bacterial communities and water-soluble organic matter (WSOM) of benthic biofilms in effluent-receiving rivers remains unknown. Here, we investigated the quality of WSOM and the evolution of bacterial communities in benthic biofilm to evaluate the ecological impacts of effluent discharge on a representative receiving water. Tryptophan-like proteins showed an increased proportion in biofilms collected from the discharge area and downstream from the WWTP, especially in summer. Biofilm WSOM showed weak humic character and strong autochthonous components, and species turnover was proven to be the main factor governing biofilm bacteria community diversity patterns. The bacterial community alpha diversity, interspecies interaction, biological index, and humification index were signally altered in the biofilms from the discharge area, while the values were more similar in biofilms collected upstream and downstream from the WWTP, indicating that both biofilm bacterial communities and WSOM characters have resilience capacities. Although effluent discharge simplified the network pattern of the biofilm bacterial community, its metabolic functional abundance was basically stable. The functional abundance of carbohydrate metabolism and amino acid metabolism in the discharge area increased, and the key modules in the non-random co-occurrence network also verified the important ecological role of carbon metabolism in the effluent-receiving river. The study sheds light on how benthic biofilms respond to effluent discharge from both ecological and material points of view, providing new insights on the feasibility of utilizing benthic biofilms as robust indicators reflecting river ecological health.

Highlights

Introduction published maps and institutional affilThe ecological health of urban rivers and internal lakes have been cumulatively affected by anthropogenic activities
We investigated how benthic biofilm bacterial communities and In water-soluble organic matter (WSOM)
We found that fluorescence index (FI) was a common key factor influencing the composition of bacterial communities in both seasons

Summary

Introduction

The ecological health of urban rivers and internal lakes have been cumulatively affected by anthropogenic activities. A major impact of urbanization is inputs from wastewater treatment plants (WWTPs) [1]. With the increasing scale of treated sewage, effluent discharge has become one of the most important sources of river replenishment. WWTPs release a multitude of nutrients, dissolved organic matter (DOM), and micropollutants, e.g., pharmaceuticals and personal care products [2,3]. Synthetic chemicals and nutrients mix and enter the receiving waterbodies, triggering eutrophication and altering biogeochemical cycling in fluvial ecosystems [4]. Effluent-receiving waterbodies have been regarded as environmental sensitive regions and have attracted intensive research concerns [5]

Results

Discussion

Conclusion