Composition of soil bacterial communities associated with urban stormwater detention basins and their predicted functional roles in N cycle.

AIMS: Stormwater detention basins serve as vital components in mitigating the adverse effects of urban runoff, and investigating the microbial dynamics within these systems is crucial for enhancing their performance and pollutant removal capabilities. The aim of this study was to examine and compare the soil bacterial communities in two stormwater detention basins located on the Edwards Aquifer in Bexar County, Texas, USA, and evaluate how soil physiochemical properties may affect them. METHODS AND RESULTS: Each basin soil was sampled in two different seasons at varying depths and the structure of microbial communities was examined using paired end Illumina sequencing using V3 and V4 region of 16S rRNA gene. PICRUSt2 was used to predict functional genes in the nitrogen cycle. In addition, soil physicochemical properties such as pH, carbon, nitrogen, and phosphorus and particle size were examined. A beta diversity analysis revealed that basins had distinctive microbial communities. Additionally, soil particle size, phosphorus and ammonia significantly correlated with some of the dominant phyla in the basins. Proteobacteria and Acidobacteria showed a positive correlation with the relative abundances of nitrogen-cycling genes, while Actinobacteria showed a negative correlation. CONCLUSIONS: This study evaluated the associations between soil physicochemical properties and microbial community dynamics in stormwater basins. The study also predicts the relative abundance of nitrogen cycling genes, suggesting shared functional traits within microbial communities. The findings have implications for understanding the potential role of microbial communities in nitrogen cycling processes and contribute to developing sustainable stormwater management strategies and protecting water quality in urban areas.

Effects of metal oxide nanoparticles on nitrification in wastewater treatment systems: A systematic review.

While the variety of engineered nanoparticles used in consumer products continues to grow, the use of metal oxide nanoparticles in electronics, textiles, cosmetics and food packaging industry has grown exponentially in recent years, which will inevitably result in their release into wastewater streams in turn impacting the important biological processes in wastewater treatment plants. Among these processes, nitrification play a critical role in nitrogen removal during wastewater treatment, however, it is sensitive to a wide range of inhibitory substances including metal oxide nanoparticles. Therefore, it is essential to systematically asses the effects of metal oxide nanoparticles on nitrification in biological wastewater treatment systems. In this review we discuss the present scenario of metal oxide nanoparticles and their impact on biological wastewater treatment processes, specifically nitrogen removal through nitrification. We also summarize the various methods used to measure nitrification inhibition by metal oxide nanoparticles and highlight corresponding results obtained using those methods. Finally, the key research gaps that need to be addressed in future are discussed.

Candidatus Accumulibacter phosphatis clades enriched under cyclic anaerobic and microaerobic conditions simultaneously use different electron acceptors.

Lab- and pilot-scale simultaneous nitrification, denitrification and phosphorus removal-sequencing batch reactors were operated under cyclic anaerobic and micro-aerobic conditions. The use of oxygen, nitrite, and nitrate as electron acceptors by Candidatus Accumulibacter phosphatis during the micro-aerobic stage was investigated. A complete clade-level characterization of Accumulibacter in both reactors was performed using newly designed qPCR primers targeting the polyphosphate kinase gene (ppk1). In the lab-scale reactor, limited-oxygen conditions led to an alternated dominance of Clade IID and IC over the other clades. Results from batch tests when Clade IC was dominant (i.e., >92% of Accumulibacter) showed that this clade was capable of using oxygen, nitrite and nitrate as electron acceptors for P uptake. A more heterogeneous distribution of clades was found in the pilot-scale system (Clades IIA, IIB, IIC, IID, IA, and IC), and in this reactor, oxygen, nitrite and nitrate were also used as electron acceptors coupled to phosphorus uptake. However, nitrite was not an efficient electron acceptor in either reactor, and nitrate allowed only partial P removal. The results from the Clade IC dominated reactor indicated that either organisms in this clade can simultaneously use multiple electron acceptors under micro-aerobic conditions, or that the use of multiple electron acceptors by Clade IC is due to significant microdiversity within the Accumulibacter clades defined using the ppk1 gene.