Exploring groundwater microbial communities for natural attenuation potential of micropollutants

Abstract

14Groundwater is a key water resource, with 45.7% of all drinking water globally being extracted from 15 groundwater. Maintaining good groundwater quality is thus crucial to secure drinking water. 16Micropollutants, such as pesticides, threaten groundwater quality which can be mitigated by 17 biodegradation. Hence, exploring microbial communities in aquifers used for drinking water 18 production is essential for understanding micropollutants biodegradation capacity. This study aimed 19 at understanding the interaction between groundwater geochemistry, pesticide presence, and 20 microbial communities in aquifers used for drinking water production. Two groundwater monitoring 21 wells located in the northeast of The Netherlands and at 500 m distance from each other were sampled 22Importance section 37 Groundwater is an essential source of drinking water. However, its quality is threathened by the 38 presence of micropollutants. Certain microorganisms are capable of degrading micropollutants. 39 However, groundwater is an unexplored environment, where the biodegradation potential of 40 naturally-present microorganisms is unknown. We thus explore how groundwater microbial ecology 41 in shaped by groundwater composition, namely geochemical parameters and micropollutants. This is 42 a first step towards understanding which microbial communities and environmental conditions 43 support natural attenuation of micropollutants. This study thus provides a first step towards 44 developing in situ bioremediation strategies to remove micropollutants from groundwater used for 45 drinking water production. 46 2.5 DNA extraction and quantification, PCR amplification and sequencing of the 16s rRNA gene, 131 and quantitative PCR (qPCR) 132 Microbial DNA was extracted from each filter using the DNeasy PowerSoil Kit (Qiagen, Hilden, 133 Germany) according to the manufacturer's instructions. The quality of DNA (average molecular size) 134

Bioremediation of pesticides: unravelling the anaerobic microbiological potential of oligotrophic drinking water aquifers

“…Half of the wells had oxygen concentrations higher than 1 mg/L (i.e., 16, 17, 25, 26, 27) (Table 2). The fact that there is oxygen in some of the shallow depths sampled waters show that not all of the monitoring wells are completely anaerobic as expected based on previous field studies ( Aldas-Vargas et al, 2019). Additionally, in two wells (i.e., shallow depths (Table 2).…”

“…Overall, the main significant explanatory variables for differences between microbial communities are electron acceptors. In a similar field study, it was already reported that electron acceptors are among the most influential factors shaping microbial communities even in the presence of pesticides (Aldas-Vargas et al, 2019). However, in the present study, pH showed to be the most significant environmental factor influencing aquifer microbial communities (Table 3).…”

“…To assess natural attenuation in the field, we need a thorough understanding of the biodegradation potential of groundwater microbial communities and the environmental conditions that select for biodegradation. Groundwater systems, especially those chosen for drinking water production are challenging environments for microorganisms, as they are anaerobic and oligotrophic, with limited and low quality carbon sources (Aldas-Vargas et al, 2019;Egli, 2010;McMahon and Chapelle, 2008).…”

“…Furthermore, microorganisms in groundwater systems are poorly described in databases, making taxonomic classification at low taxonomic levels challenging (Aldas-Vargas et al, 2019). Besides, groundwater geochemical composition shapes groundwater microbial communities rather than pesticides at micropollutant concentrations (Aldas-Vargas et al, 2019).…”

“…Furthermore, microorganisms in groundwater systems are poorly described in databases, making taxonomic classification at low taxonomic levels challenging (Aldas-Vargas et al, 2019). Besides, groundwater geochemical composition shapes groundwater microbial communities rather than pesticides at micropollutant concentrations (Aldas-Vargas et al, 2019). To expand our understanding of the diversity of microbial communities under different groundwater conditions, we sampled an entire drinking water location and performed metagenomics sequencing to obtain hints about the overall natural attenuation potential in drinking water locations.…”