Arda Gülay

Arda Gülay

Marie Curie Postdoctoral researcher

About

30
Publications
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609
Citations

Publications

Publications (30)
Preprint
Full-text available
The uptake of extracellular electrons from cathodes by microbes is a recently discovered phenomenon. However, current knowledge on the diversity of microbes accepting extracellular electrons and populating biocathodes is scarce. Research is required to explore the distribution of extracellular electron uptake metabolism in the tree of life across m...
Article
Full-text available
Nitrification, the oxidative process converting ammonia to nitrite and nitrate, is driven by microbes and plays a central role in the global nitrogen cycle. Our earlier investigations based on 16S rRNA and amoA amplicon analysis, amoA quantitative PCR and metagenomics of groundwater-fed biofilters indicated a consistently high abundance of comammox...
Preprint
Full-text available
Nitrification, the oxidative process converting ammonia to nitrite and nitrate, is driven by microbes and plays a central role in the global nitrogen cycle. Our earlier metagenomics, amoA-amplicon, and amoA-qPCR based investigations of groundwater-fed biofilters indicated a consistently high abundance of comammox Nitrospira, and we hypothesized tha...
Article
Although earlier circumstantial observations have suggested the presence of iron oxidizing bacteria (IOB) in groundwater-fed rapid sand filters (RSF), ferrous iron (Fe(II)) oxidation in this environment is often considered a chemical process due to the highly oxic and circumneutral pH conditions. Due to the low water temperature (5–10°C), typical o...
Article
The subdivision of biofilm reactor in two or more stages (i.e., reactor staging) represents an option for process optimisation of biological treatment. In our previous work, we showed that the gradient of influent organic substrate availability (induced by the staging) can influence the microbial activity (i.e., denitrification and pharmaceutical b...
Article
We investigated the density and distribution of total bacteria, canonical Ammonia Oxidizing Bacteria (AOB) (Nitrosomonas plus Nitrosospira), Ammonia Oxidizing Archaea (AOA), as well as Nitrobacter and Nitrospira in rapid sand filters used for groundwater treatment. To investigate the spatial distribution of these guilds, filter material was sampled...
Article
Community assembly is a central topic in microbial ecology: how do assembly processes interact and what is the relative contribution of stochasticity and determinism? Here, we exposed replicate flow-through biofilm systems, fed with nitrite-supplemented tap water, to continuous immigration from a source community, present in the tap water, to deter...
Article
Allylthiourea (ATU) and chlorate ( ) are often used to selectively inhibit nitritation and nitratation. In this work we identified challenges with use of these compounds in inhibitory assays with filter material from a biological rapid sand filter for groundwater treatment. Inhibition was investigated in continuous-flow lab-scale columns, packed wi...
Conference Paper
Full-text available
Four main processes are considered to drive microbial community assembly: selection, drift, dispersal and speciation. These processes occur simultaneously, but the extent to which each process contributes to community assembly is unclear in natural communities. We exposed a high-throughput flow-through biofilm system to continuous immigration from...
Article
Full-text available
The environmental stimulants and inhibitors of conjugal plasmid transfer in microbial communities are poorly understood. Specifically, it is not known whether exposure to stressors may cause a community to alter its plasmid uptake ability. We assessed whether metals (Cu, Cd, Ni, Zn) and one metalloid (As), at concentrations causing partial growth i...
Article
The new paradigm for used water treatment suggests the use of short solid retention times (SRT) to minimize organic substrate mineralization and to maximize resource recovery. However, little is known about the microbes and the underlying biogeochemical mechanisms driving these short-SRT systems. In this paper, we report the start-up and operation...
Article
Rapid gravity sand filtration is a drinking water production technology widely used around the world. Microbially catalyzed processes dominate the oxidative transformation of ammonia, reduced manganese and iron, methane and hydrogen sulfide, which may all be present at millimolar concentrations when groundwater is the source water. In this study, s...
Article
Full-text available
Here, we document microbial communities in rapid gravity filtration units, specifically serial rapid sand filters (RSFs), termed prefilters (PFs) and after- filters (AFs), fed with anoxic groundwaters low in organic carbon to prepare potable waters. A comprehensive 16S rRNA-based amplicon sequencing survey revealed a core RSF microbiome comprising...
Article
Exploring the variation in microbial community diversity between locations (β diversity) is a central topic in microbial ecology. Currently there is no consensus on how to set the significance threshold for β diversity. Here, we describe and quantify the technical components of β diversity, including those associated with the process of subsampling...
Article
Mineral coating develops on the filter grain surface when groundwater is treated via rapid sand filtration in drinking water production. Coating certainly changes the physical and chemical properties of the filter material, but little is known about its effect on the activity, colonization, diversity and abundance of microbiota. This study reveals...
Article
Full-text available
Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration can bring the rapid and long-term suppression of NO...
Article
Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully physicochemical process. However, persistently low te...

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Projects

Projects (4)
Project
The recent discovery of comammox Nitrospira represents a new paradigm in nitrification. Using rapid sand filters as a model system, this project aims to understand the ecology and niche space of nitrifiers, including comammox Nitrospira. This project further aims to develop an understanding of the physiology and metabolism of comammox Nitrospira and the evolutionary history of the comammox pathway using genomic and traditional microbiological methods.